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- [Woman] I agree with
that, I actually don't like.

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- [Matthew] All right (clears throat)

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can everyone hear me okay?

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You don't all have to respond.

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If you can't hear, you
can just send a message

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through the discussion
or chat function of the,

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of the zoom interface and
I'll be able to see that

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and can can answer or if
you're having trouble hearing,

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you can just also speak
up and, and let me know.

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So welcome to "Human Anatomy
Through Medical Imaging"

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or Rad 396 as it's numbered

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in the forthcoming course catalog.

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I'm Matt Geeslin.

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I'm one of the radiologists here at UVM MC

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and one of the co-directors
of this course.

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You'll hear from Dmitriy
Axelrod in the second portion

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of this first lecture, who
is the other co-director

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for this course.

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And then you'll hear from a number

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of other subspecialty
faculties throughout the,

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throughout the course as a
whole covering all of anatomy.

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Today's lecture, well I'll also note this,

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you'll be getting
communication, obviously,

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through Blackboard, which if you're here,

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obviously you've got it already.

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And Christine Boomer
and Jess Mattson Gammel

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are also helping out with this course

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and do basically the, all
of the administrative work

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that is required to
make this course happen.

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And we couldn't do this without them.

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And so you'll, you'll
also likely be hearing

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from them throughout the course.

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And so just to put that on your radar.

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So I think Jess and Christina

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are probably joining today as well.

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So hello, and thank you again.

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So, let's talk quick about
the first lecture here.

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Given that this is a
course in human anatomy

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that is gonna be conveyed
through medical imaging and,

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and in several of the, if
not all of the modalities

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in medical imaging, we
think it's appropriate

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that the first lecture
be an introduction to,

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to the imaging modalities
that you will see

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throughout the course.

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This is a two-part lecture.

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And the first, the first part,

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which I will give I'll cover
radiography, fluoroscopy,

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computer tomography, or CT
scans and nuclear imaging.

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And this will be very macroscopic

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and so there won't be a great
deal of detail covered here.

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What you will find throughout the,

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the lecture is, or are, slides that,

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that are marked with some kind of icon.

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And those are, can be noted

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or remembered as slides that are,

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are viewed as particularly important for,

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for learning by the lecturer.

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You'll also find that it is mentioned

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in the syllabus that if
it's not in the lecture,

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despite the fact that we have
textbooks for the course,

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which we certainly refer you to for,

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for a more detailed description,

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what you're responsible for

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on the exams is what's, what's
covered in the lectures and,

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and not beyond that.

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But reviewing the text is also helpful.

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It puts things in context for,

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for the anatomic concepts
that we, that we covered here.

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So the goal of this first lecture

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with imaging modalities is
to introduce the modalities

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as a whole and, and these
modalities that we use

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to convey the anatomic structures

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and the relationships
between those structures

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throughout the course,

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and then do just sort
of a qualitative survey

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of the physics underlying each modality.

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They're not gonna be any
equations or anything like that.

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It's just to give you an
appreciation of the physics

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that have to be attended to when you,

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when you think about image
modality development and,

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and utilization thereafter.

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But before we go into that we'll,

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I'll introduce a slide
here that will be relevant

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throughout the course and
that is the anatomic planes.

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This slide is taken from Moore and Dalley,

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one of the texts for the course.

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Here you can see "Clinically
Orientated Anatomy."

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(clears throat) Which is available

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through Dana Medical Library.

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And here the planes, as
we term them medically,

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are the sagittal plane here on the left,

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the frontal or coronal plane,

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we use the term coronal
here. in the middle.

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And then the axial
plane here on the right.

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And we'll recur to that,

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that becomes particularly relevant

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with three dimensional reconstructions

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or multiplane reconstructions,
which are used in CT and MRI.

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So to, to some degree of the physics.

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When we think about
particular the modalities

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that we'll be discussing
today, radiography,

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fluoroscopy, CT, and nuclear medicine,

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we have to think about them in the context

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of the electromagnetic spectrum.

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So here probably a familiar figure to,

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to many, if not all of you,

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we have the electromagnetic spectrum.

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In the middle here, visible light.

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Just to the left of visible
light ultraviolet light.

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And, and just to the left of visible light

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is when things start to become worrisome

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for damage to the human.

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And, and so the first
several modalities we,

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we will review are, use x-rays as sort

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of the workhorse for image generation

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and the last one, nuclear
imaging, uses gamma rays,

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as well as alpha and beta rays.

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One thing to note with regard

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to the electromagnetic spectrum,

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and I have some equations
listed down here.

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It's not because it's, you know,

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required for memory or, or deployment.

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It's just to give you a
sense of the relationships

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between the variables.

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So on the left side of the
electromagnetic spectrum,

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you'll note that the
wavelength is quite short,

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the frequency is high.

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So if you look at the energy
here related to frequency,

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you'll note that they are
directly proportional,

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and you also can tell, oops, going back,

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from the electromagnetic spectrum,

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shorter wave length has higher
frequency, higher energy.

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As we to go to the right
side of the spectrum,

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we have a longer way of length here

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resultant to lower frequency
and a resultant lower energy.

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So let's begin with radiography.

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We'll go through the radiation
used in these modalities.

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So radiography being the modality.

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Then we'll go over the generation of,

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of the radiation used, how
we detect that radiation,

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and display it to form an image,

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and then some of the
uses for this modality.

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And if you ever see a
link in the PowerPoint

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or in a, a PDF of the lecture, you can,

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you just copy paste that into a browser,

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and it will have a
relevant, a relevant video.

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In this case it's one of radiography.

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All right, so when we
think about radiography,

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let's begin with generation of x-rays.

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Here to the right we have a illustration

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or a cartoon of an x-ray tube.

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And an x-ray tube is required
for the generation of x-rays.

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In this process of x-ray
generation from an x-ray tube,

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electrons are quote unquote,

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"boiled off" what is called a filament.

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And the filament here is this green wire

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within the cathode
component of an x-ray tube.

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And when these electrons are boiled off,

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that is called thermionic
emission of electrons.

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Once the electrons are
off the filament here,

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they travel, or they exist in the space

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between the cathode and the anode.

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And a high voltage is
applied between the cathode

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and the anode in order to attract

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and accelerate the
electrons across the space,

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and to collide them with the anode here.

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This entire structure
here is called the anode.

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Upon striking the anode,

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the electron, the electrons
upon striking the anode,

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a variety of events that occur,

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including the one we're interested in

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which is x-ray radiation.

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We also produce things that,

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that are not useful for image generation,

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including photo electrons,
auger electrons,

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and of the least use but of some

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of the most significant
design aspect of an x-ray tube

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is the large amount of
heat that is generated

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when these electrons are
accelerated at the anode target.

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And this small little red
line here denotes the target.

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You'll note one up here as well.

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And I'll explain why you
see that on the next slide.

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So with respect to the
heat that is generated

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on the focal spot, again,
red lines on this anode.

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When, when the electron
beam collides with,

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with the anode we rotate or modern elect,

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x-ray tubes, rotate the anode,
denoted here by this arrow,

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so that that heat is dispersed and,

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and this avoids the entirety
of the electrons accelerated

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across that space colliding
with one point on the anode.

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This is important because
of heat generation.

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And with regard to that heats

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or temperatures can reach up to 4,000

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or above 4,000 degrees Fahrenheit during

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what's called an exposure,

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which is really just saying while the,

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while the x-ray tube is on.

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So as a result of that,

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the anode has certain
material requirements,

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chief among them being

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that it has a very high
melting temperature.

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Two metals are often
used one being tungsten,

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which you'll also note at least in former,

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former light bulbs, the
filaments is tungsten and,

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and another is molybdenum.

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Once the x-rays are generated,
they exit inferiorly here,

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the x-ray window.

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So more x-rays are generated

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than just exit the x-ray window,

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but we are only interested
in capturing those

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that exit the x-ray window

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because they are traveling
in the correct direction

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for image generation.

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Everything else is absorbed
by the encasement here,

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usually lead, of the x-ray tube.

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All right, so here I have
the x-ray tube turned

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on its side for illustrative purposes,

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and we'll think about now detection

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of our x-rays that we have generated.

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So once the x-rays exit the x-ray tube,

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they diverge toward the
patient in straight lines.

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So think of this as a point source.

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Upon reaching the patient,
these x-rays will interact

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with various tissues in
the patient labeled here.

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So we have heart, we have back.

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This would really be vertebral bodies.

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So we have lungs, lots
of air in the lungs.

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And then we have some
peripheral soft tissues here

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denoted in gray along the
outside of the patient.

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X-rays are attenuated or another,

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another way to think
about it that is stopped

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by the tissues within the patient,

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as a function of the density of the tissue

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with which they interact.

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So if you have a high
density tissue like bone,

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bone is going to do a
good job stopping x-rays.

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So bone will attenuate an x-ray.

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When you, when you stop an x-ray prior

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to it getting to the detector,

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that information or lack
of information is used

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in image display.

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So thinking about image display,

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here we have our x-ray
tube, which is our source.

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Our x-ray divergence toward the patient.

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A very simple detector drawing
here behind the patient,

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where the x-rays are detected,

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and then the ultimate display.

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So once an x-ray interacts
with the detector, right?

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That, that means that it
got through the patient.

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In so doing that x-ray will
interact with a detector

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and an, and an energy
conversion takes place.

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So the, the incident x-ray and photon

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will be converted to,
to electrical energy.

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So we're going from electromagnetic energy

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00:35:56,620 --> 00:35:58,780
to electrical energy and,

256
00:35:58,780 --> 00:36:00,660
and we're using that electrical energy

257
00:36:00,660 --> 00:36:04,683
to create a signal that is
then used for image display.

258
00:36:07,167 --> 00:36:10,870
And this image display, it produces a map

259
00:36:10,870 --> 00:36:12,780
in the case of radiography and,

260
00:36:12,780 --> 00:36:16,240
and computer tomography, and fluoroscopy

261
00:36:16,240 --> 00:36:18,380
of the relative density or,

262
00:36:18,380 --> 00:36:22,040
or attenuation of patient tissues

263
00:36:22,040 --> 00:36:23,770
through which the x-rays have passed.

264
00:36:23,770 --> 00:36:26,760
So the spectrum of x-ray
attenuation ranges from,

265
00:36:26,760 --> 00:36:31,400
of course, entirely, which
can be the case in bone

266
00:36:31,400 --> 00:36:34,450
or partially, which you
might see in soft tissue

267
00:36:34,450 --> 00:36:38,120
or not at all, if it
just goes through air,

268
00:36:38,120 --> 00:36:40,883
such as certain, certain
areas of the lung.

269
00:36:43,090 --> 00:36:45,380
So here we have it,
the relative densities.

270
00:36:45,380 --> 00:36:47,060
White on an x-ray, for example,

271
00:36:47,060 --> 00:36:50,710
corresponds to significant attenuation

272
00:36:50,710 --> 00:36:52,150
for a conventional radiography.

273
00:36:52,150 --> 00:36:55,730
So here we see white
corresponding to the bones,

274
00:36:55,730 --> 00:36:59,340
bones we know are dense
relative to soft tissue

275
00:36:59,340 --> 00:37:01,900
and certainly to air,
and so that attenuates

276
00:37:01,900 --> 00:37:05,570
or stops the x-ray before
it gets to the detector.

277
00:37:05,570 --> 00:37:10,350
And the detector can assign, produces,

278
00:37:10,350 --> 00:37:13,140
is able to, is able to display that

279
00:37:14,140 --> 00:37:16,610
in comparison to the
other relative densities

280
00:37:16,610 --> 00:37:18,123
through which the x-rays pass.

281
00:37:19,380 --> 00:37:23,260
Same example, black corresponds
to little or no attenuation,

282
00:37:23,260 --> 00:37:25,990
i.e. a large number of x-rays made it

283
00:37:25,990 --> 00:37:28,900
through this part of the
patient in this case the lung,

284
00:37:28,900 --> 00:37:32,763
and then interacted with the detector.

285
00:37:33,852 --> 00:37:38,707
(clears throat) All right,
this is a great segue for the,

286
00:37:38,707 --> 00:37:42,640
the classically described
radiographic densities.

287
00:37:42,640 --> 00:37:47,200
So here we have them
numbered one, two, three,

288
00:37:47,200 --> 00:37:52,200
three again, four, and five.

289
00:37:52,230 --> 00:37:57,230
So number one air, or
lung, air being in lung,

290
00:37:58,630 --> 00:38:00,880
is the lowest of the
radiographic densities.

291
00:38:00,880 --> 00:38:02,480
So it's very lucent.

292
00:38:02,480 --> 00:38:05,750
Number two, here this one
is a little bit tricky

293
00:38:05,750 --> 00:38:07,990
to perceive because
there's, it's kind of hard

294
00:38:07,990 --> 00:38:10,070
to find fat on an, on an x-ray.

295
00:38:10,070 --> 00:38:11,367
Much easier to find it on CT.

296
00:38:11,367 --> 00:38:13,560
But here we have what is a fat plane

297
00:38:13,560 --> 00:38:15,780
between two muscles like the,

298
00:38:15,780 --> 00:38:18,830
the latissimus dorsi peripherally here,

299
00:38:18,830 --> 00:38:20,453
and the serratus anterior.

300
00:38:21,500 --> 00:38:24,980
Three, we have soft tissue shown here,

301
00:38:24,980 --> 00:38:27,670
three and three and shown up here as well.

302
00:38:27,670 --> 00:38:29,650
And in this case, that would be muscle

303
00:38:29,650 --> 00:38:31,350
and overlying skin.

304
00:38:31,350 --> 00:38:35,400
Four, we have bone, so we have four here

305
00:38:35,400 --> 00:38:37,650
on the lateral clavicle throughout.

306
00:38:37,650 --> 00:38:40,370
We have all of the ribs, the scapula,

307
00:38:40,370 --> 00:38:44,870
we also have a four on the
finger, bone on the finger.

308
00:38:44,870 --> 00:38:48,360
And then the fifth is metal
and here we have a foreign body

309
00:38:48,360 --> 00:38:50,133
in the patient's finger staple.

310
00:38:53,410 --> 00:38:56,220
All right, so some examples and uses

311
00:38:56,220 --> 00:39:00,060
of radiography here
shown we use radiography

312
00:39:00,060 --> 00:39:05,060
for quick scanning for
pathologic processes.

313
00:39:05,700 --> 00:39:09,140
So radiography is great
for detecting fractures,

314
00:39:09,140 --> 00:39:10,810
great for detecting foreign bodies,

315
00:39:10,810 --> 00:39:11,670
usually pretty good

316
00:39:11,670 --> 00:39:14,990
at detecting cardiopulmonary emergencies,

317
00:39:14,990 --> 00:39:17,750
such as a pneumothorax, which
we have an example of here.

318
00:39:17,750 --> 00:39:20,510
This, this lung is too black compared

319
00:39:20,510 --> 00:39:24,100
to the contralateral
left side of the lung,

320
00:39:24,100 --> 00:39:27,740
which is hyper dense or
of increased density.

321
00:39:27,740 --> 00:39:30,500
And that's because
there's too much air here.

322
00:39:30,500 --> 00:39:31,367
And that's because there's air

323
00:39:31,367 --> 00:39:34,150
between the chest wall and the lung.

324
00:39:34,150 --> 00:39:35,520
So it's in the pleural space

325
00:39:35,520 --> 00:39:38,243
and that is termed a pneumothorax.

326
00:39:40,460 --> 00:39:41,293
All right.

327
00:39:42,470 --> 00:39:44,823
Brief examples of radiography.

328
00:39:45,730 --> 00:39:48,640
Fluoroscopy, again, we'll go through this

329
00:39:48,640 --> 00:39:50,510
in the same format.

330
00:39:50,510 --> 00:39:53,050
The radiation used, how we make it,

331
00:39:53,050 --> 00:39:56,590
how we detect it and how we
use it to display an image,

332
00:39:56,590 --> 00:39:59,020
and then finally some uses.

333
00:39:59,020 --> 00:40:02,020
So fluoroscopy suite,
here we have two examples.

334
00:40:02,020 --> 00:40:03,700
On the left, we have what's called

335
00:40:03,700 --> 00:40:05,830
a biplanar fluoroscopy suite.

336
00:40:05,830 --> 00:40:08,910
This is typically used in more
complex image interventions,

337
00:40:08,910 --> 00:40:13,250
such as neurointerventional, radiology,

338
00:40:13,250 --> 00:40:15,470
or innervate body
interventional radiology.

339
00:40:15,470 --> 00:40:20,470
Here on the right, we have a
gastro GI fluoroscopy suite,

340
00:40:26,720 --> 00:40:30,840
which is optimized for doing procedures,

341
00:40:30,840 --> 00:40:35,840
such as barium or Omnipaque
swallows, contrast swallows,

342
00:40:37,560 --> 00:40:40,010
swallow studies, so we're
looking at the esophagus,

343
00:40:40,010 --> 00:40:43,123
the stomach and, and the small bowel

344
00:40:43,123 --> 00:40:46,053
and large bowel as it
goes through the body.

345
00:40:48,430 --> 00:40:51,580
Image generation, when we
think about fluoroscopy.

346
00:40:51,580 --> 00:40:56,474
So again, fluoroscopy uses
x-rays just like radiography.

347
00:40:56,474 --> 00:40:59,270
And so we need an x-ray
tube, we need a detector,

348
00:40:59,270 --> 00:41:02,820
and we need a mechanism
for displaying the image.

349
00:41:02,820 --> 00:41:06,340
A big advantage of fluoroscopy is in

350
00:41:06,340 --> 00:41:08,340
that it can be done in real time.

351
00:41:08,340 --> 00:41:13,173
And that's why it is used for
image guided interventions.

352
00:41:15,030 --> 00:41:17,963
It's particularly useful for
image guided interventions.

353
00:41:19,040 --> 00:41:22,450
Additional areas where
you'll see fluoroscopy,

354
00:41:22,450 --> 00:41:25,700
which we described previously
is the barium swallow,

355
00:41:25,700 --> 00:41:30,700
so you're swallowing a
radiopaque agent such as barium,

356
00:41:31,150 --> 00:41:35,970
and you're watching that
agent travel through the,

357
00:41:35,970 --> 00:41:40,670
the esophagus, stomach,
and more distal to that,

358
00:41:40,670 --> 00:41:42,480
as it goes through the body.

359
00:41:42,480 --> 00:41:44,550
An additional one, coronary angiography,

360
00:41:44,550 --> 00:41:47,193
both YouTube videos are provided here.

361
00:41:48,770 --> 00:41:51,870
Other, other uses included,

362
00:41:51,870 --> 00:41:53,840
include image guided interventions,

363
00:41:53,840 --> 00:41:56,780
which I touched on briefly,
including neurovascular,

364
00:41:56,780 --> 00:42:01,273
cardiovascular, peripheral
vascular, and joint injection,

365
00:42:02,560 --> 00:42:04,870
as well as gastrointestinal diagnosis and,

366
00:42:04,870 --> 00:42:06,773
and rarely intervention.

367
00:42:09,380 --> 00:42:12,543
Computed tomography, same pattern.

368
00:42:13,870 --> 00:42:15,280
What's our radiation.

369
00:42:15,280 --> 00:42:16,240
How do we make it?

370
00:42:16,240 --> 00:42:18,130
How do we detect it?

371
00:42:18,130 --> 00:42:19,080
How do we display it?

372
00:42:19,080 --> 00:42:22,540
And what do we use this modality for?

373
00:42:22,540 --> 00:42:25,410
All right, so here we have,
just checking the time.

374
00:42:25,410 --> 00:42:28,900
Here we have two images of a CT scan

375
00:42:28,900 --> 00:42:31,830
or the one on the left with
the scanner cover removed.

376
00:42:31,830 --> 00:42:35,910
So here we can see the row of detectors.

377
00:42:35,910 --> 00:42:39,170
We talked a little bit about detectors in,

378
00:42:39,170 --> 00:42:42,970
in the previous modalities,
in particular radiography.

379
00:42:42,970 --> 00:42:45,400
So that is, that is the mechanism.

380
00:42:45,400 --> 00:42:46,980
That is the part of this machine,

381
00:42:46,980 --> 00:42:51,560
which allows us to convert
our electromagnetic energy,

382
00:42:51,560 --> 00:42:54,130
our x-rays into electrical energy

383
00:42:54,130 --> 00:42:57,093
so we can get an electrical
signal and make an image.

384
00:42:58,200 --> 00:43:02,930
Up here, directly across
would be the x-ray tube

385
00:43:02,930 --> 00:43:04,620
or the source.

386
00:43:04,620 --> 00:43:06,430
In here, image on the right.

387
00:43:06,430 --> 00:43:10,540
We have just a CT scanner
with (clears throat)

388
00:43:10,540 --> 00:43:12,510
Excuse me, with the cover on.

389
00:43:12,510 --> 00:43:14,720
So this is what it looks like.

390
00:43:14,720 --> 00:43:17,970
So the components going
a little more detailed

391
00:43:17,970 --> 00:43:19,810
include a power source, of course,

392
00:43:19,810 --> 00:43:21,650
the x-ray tube or tubes,

393
00:43:21,650 --> 00:43:23,640
many CT scanners actually have two,

394
00:43:23,640 --> 00:43:27,290
two x-ray tubes in
them, which allows more,

395
00:43:27,290 --> 00:43:30,630
more clever and sophisticated
image reconstruction

396
00:43:30,630 --> 00:43:35,070
as well as diagnosis based on each,

397
00:43:35,070 --> 00:43:38,200
each x-ray emitter or each x-ray tube

398
00:43:38,200 --> 00:43:40,730
putting out x-rays of a different energy.

399
00:43:40,730 --> 00:43:43,410
And if you print out x-rays
of a different energy,

400
00:43:43,410 --> 00:43:48,130
you can, you can do work
with those different energies

401
00:43:48,130 --> 00:43:52,980
for image reconstruction
and, and diagnosis.

402
00:43:52,980 --> 00:43:55,500
We have a table mechanism
for positioning the patient

403
00:43:55,500 --> 00:43:57,020
and moving them through the scanner.

404
00:43:57,020 --> 00:44:00,140
We have the scanner console here,

405
00:44:00,140 --> 00:44:03,100
including the computer room,

406
00:44:03,100 --> 00:44:07,383
where also the image reconstruction
software is deployed.

407
00:44:08,860 --> 00:44:13,860
So the process of obtaining
a tomographic image

408
00:44:14,330 --> 00:44:18,170
or a CT image is, is not,

409
00:44:18,170 --> 00:44:21,310
it's very similar to, it's not dissimilar,

410
00:44:21,310 --> 00:44:26,310
it's very similar to obtaining
a radiographic image.

411
00:44:26,470 --> 00:44:30,350
We have an x-ray tube
here, focal spot shown.

412
00:44:30,350 --> 00:44:34,010
We have the rays, x-rays,
divergent from that tube

413
00:44:34,010 --> 00:44:36,320
traveling toward the patient.

414
00:44:36,320 --> 00:44:40,740
And then we, the patient here
is the purple and the yellow.

415
00:44:40,740 --> 00:44:44,900
And then we have a row of
detectors to detect the,

416
00:44:44,900 --> 00:44:46,980
the x-rays that are incident upon,

417
00:44:46,980 --> 00:44:49,163
upon that row of detectors here again.

418
00:44:50,120 --> 00:44:54,243
Detectors, x-ray tube or the x-ray source.

419
00:44:55,150 --> 00:44:58,870
And so we'll note here
the word profile and,

420
00:44:58,870 --> 00:45:01,960
and sort of a graph that is displayed

421
00:45:01,960 --> 00:45:04,730
along the course of the
row of the detectors.

422
00:45:04,730 --> 00:45:09,660
Pay attention here to, to
these individual x-rays

423
00:45:09,660 --> 00:45:12,790
as they travel toward
the row of detectors and,

424
00:45:12,790 --> 00:45:15,320
and think about whether they are passing

425
00:45:15,320 --> 00:45:19,000
through the patient,
not through the patient,

426
00:45:19,000 --> 00:45:21,730
through the peripheral, or are
they outside of the patient

427
00:45:21,730 --> 00:45:23,410
or through the middle of the patient.

428
00:45:23,410 --> 00:45:27,290
So you can see this one
here passes entirely

429
00:45:27,290 --> 00:45:28,123
through the air.

430
00:45:28,123 --> 00:45:29,700
So it goes, it goes past the patient

431
00:45:29,700 --> 00:45:31,150
without passing through it.

432
00:45:31,150 --> 00:45:34,450
You'll see this profile here is a graph

433
00:45:34,450 --> 00:45:38,320
of the intensity of the x-ray on the,

434
00:45:38,320 --> 00:45:43,320
or the summative x-rays
on the, on the detector.

435
00:45:44,050 --> 00:45:46,020
So when an x-ray is not stopped

436
00:45:46,020 --> 00:45:47,260
before it gets to the patient,

437
00:45:47,260 --> 00:45:48,920
or x-rays are not stopped before they get

438
00:45:48,920 --> 00:45:51,200
to the detector, I'm sorry.

439
00:45:51,200 --> 00:45:53,810
You have a higher intensity
of x-rays on the detector.

440
00:45:53,810 --> 00:45:57,270
And that's what this
profile is, is represented.

441
00:45:57,270 --> 00:46:00,390
And this profile is used mathematically

442
00:46:00,390 --> 00:46:05,210
to ultimately create the
image that is displayed for,

443
00:46:05,210 --> 00:46:06,790
for CT scans.

444
00:46:06,790 --> 00:46:11,660
So relative to the outside
or beyond the patient,

445
00:46:11,660 --> 00:46:13,310
look right through the
middle of the patient

446
00:46:13,310 --> 00:46:15,040
and you'll know it's the lowest profile

447
00:46:15,040 --> 00:46:18,103
or the lowest intensity
of incident X-rays.

448
00:46:20,490 --> 00:46:25,490
This next series of figures
shows basically the same thing.

449
00:46:25,930 --> 00:46:30,350
To the left here pretend
this, this ribbon arrow,

450
00:46:30,350 --> 00:46:33,200
if you will, is the row of detectors

451
00:46:33,200 --> 00:46:34,850
as it goes around the patient

452
00:46:34,850 --> 00:46:39,850
so that the detector
spins around the patient

453
00:46:39,940 --> 00:46:43,980
as the patient is moved on
the table through the machine.

454
00:46:43,980 --> 00:46:48,230
And as a result of moving the
patient while you spin the,

455
00:46:48,230 --> 00:46:50,780
the source and the detector,

456
00:46:50,780 --> 00:46:54,700
you image the entirety of the area

457
00:46:54,700 --> 00:46:55,920
of the patient that you wanna image.

458
00:46:55,920 --> 00:46:57,830
So in this case, it
looks like they're trying

459
00:46:57,830 --> 00:47:00,103
to image the patient's chest.

460
00:47:01,406 --> 00:47:04,433
I can see the arms here, see
the patient's chest here.

461
00:47:06,340 --> 00:47:10,050
The cartoon or the
illustration to the right here

462
00:47:10,050 --> 00:47:15,050
shows how the x-ray intensity
or the profile changes

463
00:47:16,990 --> 00:47:19,930
with different projections
or different angles

464
00:47:19,930 --> 00:47:22,580
of the focal spot relative to the patient.

465
00:47:22,580 --> 00:47:25,590
So here we have it directly
above the patient passing

466
00:47:25,590 --> 00:47:28,680
from front to back,
going through the lung,

467
00:47:28,680 --> 00:47:31,680
the heart, the peripheral soft tissues.

468
00:47:31,680 --> 00:47:34,040
And we can see the varying intensity

469
00:47:34,040 --> 00:47:37,690
of the x-rays that are
incident on the detector,

470
00:47:37,690 --> 00:47:40,850
based on the tissues
through which they pass

471
00:47:40,850 --> 00:47:42,570
on their way to the detector.

472
00:47:42,570 --> 00:47:44,760
Here taken from another point.

473
00:47:44,760 --> 00:47:48,820
Remember this is that, that scanner gantry

474
00:47:48,820 --> 00:47:51,150
that's twisting around the patient.

475
00:47:51,150 --> 00:47:53,230
So it's moved to the left a little bit,

476
00:47:53,230 --> 00:47:56,020
and now it's shooting
x-rays through the patient

477
00:47:56,020 --> 00:47:57,860
from a different angle.

478
00:47:57,860 --> 00:48:01,313
And as a result, it produces a different,

479
00:48:02,940 --> 00:48:05,420
an x-ray intensity profile.

480
00:48:05,420 --> 00:48:08,160
And all of this is taken together

481
00:48:08,160 --> 00:48:12,580
and math done based on it

482
00:48:12,580 --> 00:48:16,530
to produce the reconstructed image.

483
00:48:16,530 --> 00:48:19,577
So we have x-rays go through the patient,

484
00:48:19,577 --> 00:48:22,363
hit the detector, produces the profile.

485
00:48:24,200 --> 00:48:27,700
That profile is converted
from electro magnetic

486
00:48:27,700 --> 00:48:31,630
to electrical energy that
produces an electrical signal.

487
00:48:31,630 --> 00:48:34,220
That signal is used in the computer,

488
00:48:34,220 --> 00:48:36,980
received by the computer,
used by the computer

489
00:48:36,980 --> 00:48:40,361
with complex mathematics
to ultimately create

490
00:48:40,361 --> 00:48:43,440
an image display, which we
have here on the far right,

491
00:48:43,440 --> 00:48:45,640
which is a coronal chest CT.

492
00:48:45,640 --> 00:48:47,360
And I have here denoted lung windows.

493
00:48:47,360 --> 00:48:49,560
You won't be responsible for windows.

494
00:48:49,560 --> 00:48:54,060
It's just to, to illustrate

495
00:48:54,060 --> 00:48:57,950
that you can window CT images differently

496
00:48:57,950 --> 00:49:00,010
to highlight certain features of,

497
00:49:00,010 --> 00:49:02,320
of the anatomy which you are imaging.

498
00:49:02,320 --> 00:49:03,980
So back to anatomic planes,

499
00:49:03,980 --> 00:49:06,310
which I said is gonna
be particularly useful

500
00:49:06,310 --> 00:49:09,930
when you think of cross-sectional
imaging like CT and MRI.

501
00:49:09,930 --> 00:49:12,260
We have here the sagittal plane,

502
00:49:12,260 --> 00:49:14,983
so we can see the spine nicely profiled.

503
00:49:16,110 --> 00:49:17,520
We have the coronal plane,

504
00:49:17,520 --> 00:49:19,930
we can see the liver and the kidneys

505
00:49:19,930 --> 00:49:23,300
and the spleen nicely profiled
and the bones of the pelvis.

506
00:49:23,300 --> 00:49:27,860
And then we have the axial plane,

507
00:49:27,860 --> 00:49:31,050
which I'll note, I don't
have it labeled here,

508
00:49:31,050 --> 00:49:35,460
but it is actually the left of the image,

509
00:49:35,460 --> 00:49:37,840
which is the right of the patient.

510
00:49:37,840 --> 00:49:42,440
And sometimes, sometimes if
you forget that and it's,

511
00:49:42,440 --> 00:49:45,960
if it's relevant based on
the image you're considering

512
00:49:45,960 --> 00:49:48,262
you can, you can use a little cheat

513
00:49:48,262 --> 00:49:51,700
to figure out right and
left by knowing the side

514
00:49:51,700 --> 00:49:53,270
of the organ that you're looking at.

515
00:49:53,270 --> 00:49:56,950
So in this case, we have a
liver which, which you know,

516
00:49:56,950 --> 00:49:59,690
or will learn as on the
right of the upper abdomen.

517
00:49:59,690 --> 00:50:01,030
So this one we know.

518
00:50:01,030 --> 00:50:03,660
Barring any anatomic
abnormality, of course,

519
00:50:03,660 --> 00:50:06,510
we know that we're on the
right side of the patient here.

520
00:50:07,902 --> 00:50:10,783
(sighs) All right, some
quick uses of CT scan.

521
00:50:10,783 --> 00:50:15,783
CT is used a great deal
in, in medical imaging

522
00:50:16,022 --> 00:50:18,670
and as you can see here,
there are several uses.

523
00:50:18,670 --> 00:50:20,810
So we have a head CT scan.

524
00:50:20,810 --> 00:50:24,163
We have an axial chest
CT in the axial plane

525
00:50:24,163 --> 00:50:27,450
of a chest CT scan, which
you've seen already.

526
00:50:27,450 --> 00:50:31,623
We have a coronal CT scan of the abdomen,

527
00:50:31,623 --> 00:50:36,623
showing the abdominal organs
here, liver, small bowel,

528
00:50:37,160 --> 00:50:39,910
large bowel, spleen,
stomach to name a few,

529
00:50:39,910 --> 00:50:42,640
you'll go into more detail
with that as you get

530
00:50:42,640 --> 00:50:45,150
to the chest abdomen
section of this course.

531
00:50:45,150 --> 00:50:49,337
And then reconstructed cardiac CT showing

532
00:50:53,200 --> 00:50:56,230
what is likely the left
anterior descending artery here

533
00:50:56,230 --> 00:51:00,013
displayed showing coronary plaques.

534
00:51:01,590 --> 00:51:04,610
I'm sorry, left coronary
artery here showing plaques,

535
00:51:04,610 --> 00:51:09,130
areas of stenosis, and this reconstructed

536
00:51:09,130 --> 00:51:12,520
to show the sagittal
projection of the heart

537
00:51:12,520 --> 00:51:14,390
in this case, the left ventricle,

538
00:51:14,390 --> 00:51:16,850
as well as the axial
projection of the heart

539
00:51:16,850 --> 00:51:19,330
in this case here left ventricle.

540
00:51:19,330 --> 00:51:23,313
And finally a 3D reconstruction
also obtained with CT.

541
00:51:25,820 --> 00:51:28,190
Quick comment on contrast administration.

542
00:51:28,190 --> 00:51:31,630
So CT, one of the additional uses of,

543
00:51:31,630 --> 00:51:36,630
or pieces of CT that make it
quite useful is that you can,

544
00:51:37,240 --> 00:51:39,310
you can add contrast agent,

545
00:51:39,310 --> 00:51:43,960
which is something that attenuates x-rays,

546
00:51:43,960 --> 00:51:47,340
and you can add that by adjusting it

547
00:51:47,340 --> 00:51:50,330
so it goes through your
gastrointestinal system

548
00:51:50,330 --> 00:51:53,163
from esophagus to stomach,
to small and large bowel.

549
00:51:54,220 --> 00:51:57,670
You can also give contrast
or administer contrast

550
00:51:57,670 --> 00:52:01,130
through the, through a peripheral vein,

551
00:52:01,130 --> 00:52:04,900
in which case you will be
opacifying the vasculature.

552
00:52:04,900 --> 00:52:08,860
And you can, you can image
at different times relative

553
00:52:08,860 --> 00:52:11,540
to the time point at which you injected

554
00:52:11,540 --> 00:52:16,540
to produce different a enhancement
pattern for your image.

555
00:52:18,520 --> 00:52:20,520
So we have that shown here.

556
00:52:20,520 --> 00:52:22,180
We have an unenhanced CT scan.

557
00:52:22,180 --> 00:52:26,880
So in this image or two
images on the top left,

558
00:52:26,880 --> 00:52:29,680
no contrast was
administered either ingested

559
00:52:29,680 --> 00:52:32,178
or intravascular.

560
00:52:32,178 --> 00:52:34,170
The image on the top right,

561
00:52:34,170 --> 00:52:36,230
we have two contrast agents on board.

562
00:52:36,230 --> 00:52:38,520
We have an intravenous contrast agent,

563
00:52:38,520 --> 00:52:42,440
which can be inferred by
opacification of the portal

564
00:52:42,440 --> 00:52:44,640
and hepatic veins within the liver.

565
00:52:44,640 --> 00:52:49,640
We also have an, an oral contrast agent

566
00:52:50,290 --> 00:52:53,560
that has been administered and that is,

567
00:52:53,560 --> 00:52:57,624
can be, can be inferred by
the relative opacification

568
00:52:57,624 --> 00:53:00,238
of the small bowel here, left hemiabdomen,

569
00:53:00,238 --> 00:53:02,575
and the large ball
here, right hemiabdomen.

570
00:53:02,575 --> 00:53:05,470
And then lastly, here we
have a different phase

571
00:53:05,470 --> 00:53:08,050
of intravascular contrast administration,

572
00:53:08,050 --> 00:53:09,410
the arterial phase.

573
00:53:09,410 --> 00:53:14,410
So here we can see the
aorta shown here in,

574
00:53:15,160 --> 00:53:19,990
in cross section or in the axial section

575
00:53:19,990 --> 00:53:22,970
and as well the aorta and portions

576
00:53:22,970 --> 00:53:26,266
of the heart shown coronally.

577
00:53:26,266 --> 00:53:28,140
And just drawing your attention here.

578
00:53:28,140 --> 00:53:30,050
So we have an axial image, right?

579
00:53:30,050 --> 00:53:34,180
Portal venous phase axial
image, arterial phase.

580
00:53:34,180 --> 00:53:36,950
Note the difference in the
appearance of the kidney,

581
00:53:36,950 --> 00:53:39,570
there's the kidney, portal venous phase

582
00:53:39,570 --> 00:53:43,110
and the kidney on the arterial phase,

583
00:53:43,110 --> 00:53:46,207
the enhancement pattern varies.

584
00:53:46,207 --> 00:53:49,683
And that's illustrated here
best probably with the kidney.

585
00:53:50,990 --> 00:53:53,293
All right, on to nuclear medicine.

586
00:53:54,210 --> 00:53:59,210
So same, same pattern, right?

587
00:53:59,920 --> 00:54:01,373
Radiation first.

588
00:54:03,560 --> 00:54:04,720
How do we get it?

589
00:54:04,720 --> 00:54:07,010
How do we detect it and
how do we display it?

590
00:54:07,010 --> 00:54:09,870
And then what do we use this modality

591
00:54:09,870 --> 00:54:11,853
or these modalities for clinically?

592
00:54:12,810 --> 00:54:15,590
To the right here which, which is shown

593
00:54:15,590 --> 00:54:18,700
and can be seen by clicking the link

594
00:54:18,700 --> 00:54:23,587
to the website is a cardiac
nuclear medicine test

595
00:54:26,790 --> 00:54:29,060
looking for cardiac viability.

596
00:54:29,060 --> 00:54:31,150
So they're looking
there, looking for areas

597
00:54:31,150 --> 00:54:35,250
of decreased blood flow
or perfusion is the,

598
00:54:35,250 --> 00:54:38,480
is the word used in, in the heart.

599
00:54:38,480 --> 00:54:39,590
And you can see it shown here

600
00:54:39,590 --> 00:54:41,010
in multiple different projections.

601
00:54:41,010 --> 00:54:45,270
So an axial, sagittal and, and coronal.

602
00:54:49,210 --> 00:54:53,329
Okay, so nuclear medicine,
some basics here.

603
00:54:53,329 --> 00:54:55,870
The radiopharmaceutical is a term

604
00:54:55,870 --> 00:54:57,646
you'll become familiar with

605
00:54:57,646 --> 00:55:01,810
and radiopharmaceuticals are compounds

606
00:55:01,810 --> 00:55:05,540
that contain small
amounts of radio isotopes.

607
00:55:05,540 --> 00:55:09,310
Radio isotopes themselves
are produced (clears throat)

608
00:55:09,310 --> 00:55:14,023
Excuse me, in nuclear reactors
or particle accelerators.

609
00:55:23,970 --> 00:55:27,600
Radio isotopes upon being
produced are then tagged

610
00:55:27,600 --> 00:55:30,500
onto certain molecules based

611
00:55:30,500 --> 00:55:32,860
on their biologic characteristics.

612
00:55:32,860 --> 00:55:37,130
Once a radio isotope or
biological molecule are joined,

613
00:55:37,130 --> 00:55:39,003
a radiopharmaceutical is born.

614
00:55:40,260 --> 00:55:44,590
Upon administration of the
radiopharmaceutical the,

615
00:55:44,590 --> 00:55:48,340
the drug migrates to the
region of the body where,

616
00:55:48,340 --> 00:55:51,510
where the specific molecule
is biochemically processed.

617
00:55:51,510 --> 00:55:55,150
And that underlies the whole
point of a radiopharmaceutical.

618
00:55:55,150 --> 00:55:58,530
We want these agents to be taken up

619
00:55:58,530 --> 00:56:01,260
in particular areas of the body

620
00:56:01,260 --> 00:56:03,090
to emit radiation from there

621
00:56:03,090 --> 00:56:04,910
and then we detect that radiation.

622
00:56:04,910 --> 00:56:08,850
We infer based on their
concentration in certain areas,

623
00:56:08,850 --> 00:56:11,090
the presence of the body, the presence,

624
00:56:11,090 --> 00:56:13,973
or absence of the pathologic process.

625
00:56:15,810 --> 00:56:16,643
All right.

626
00:56:17,510 --> 00:56:22,380
So, couple more basics on, and
distinctions in particular,

627
00:56:22,380 --> 00:56:25,860
with nuclear medicine compared to other,

628
00:56:25,860 --> 00:56:27,780
other modalities that we reviewed today.

629
00:56:27,780 --> 00:56:32,330
So nuclear medicine involves the detection

630
00:56:32,330 --> 00:56:34,960
of radiation that has been administered

631
00:56:36,200 --> 00:56:37,420
from within the body.

632
00:56:37,420 --> 00:56:39,500
So the radiation is inside the body

633
00:56:39,500 --> 00:56:42,160
and it's being emitted
from within the body.

634
00:56:42,160 --> 00:56:46,520
And we are detecting it
as it, as it (stammers)

635
00:56:48,770 --> 00:56:53,430
exits the body, if you will,
using our image detectors and,

636
00:56:53,430 --> 00:56:57,003
and the radiation again is
gamma, beta, and alpha rays.

637
00:56:57,875 --> 00:57:00,480
CT, the other modalities that we reviewed,

638
00:57:00,480 --> 00:57:05,480
CT, radiography, and fluoroscopy
involve the administration

639
00:57:05,530 --> 00:57:08,340
of radiation from outside the body,

640
00:57:08,340 --> 00:57:11,003
passage of that radiation
through the body,

641
00:57:12,140 --> 00:57:13,890
and detection of that radiation

642
00:57:13,890 --> 00:57:15,390
on the other side of the body.

643
00:57:17,700 --> 00:57:19,840
Another point about nuclear medicine is

644
00:57:19,840 --> 00:57:24,020
that it can be used for
both diagnostic purposes,

645
00:57:24,020 --> 00:57:25,770
as well as therapeutic purposes.

646
00:57:25,770 --> 00:57:30,480
So because these, these agents,
or the radiopharmaceuticals,

647
00:57:30,480 --> 00:57:33,770
emit radiation, they can
not only be detected,

648
00:57:33,770 --> 00:57:37,293
but as you probably know,
radiation can be used

649
00:57:37,293 --> 00:57:42,293
to destroy unwanted tissues
such as malignancies or cancers.

650
00:57:43,570 --> 00:57:46,740
And so you'll, you may find
as the course progresses,

651
00:57:46,740 --> 00:57:51,603
that certain, certain uses
of therapeutic radiation

652
00:57:52,970 --> 00:57:57,970
are reviewed for, for the purpose of,

653
00:57:58,410 --> 00:58:02,140
of reviewing certain anatomic concepts.

654
00:58:02,140 --> 00:58:03,960
All right, so nuclear medicine process.

655
00:58:03,960 --> 00:58:05,710
Cyclotron on the left, that's used

656
00:58:05,710 --> 00:58:07,842
to produce the radiopharmaceutical.

657
00:58:07,842 --> 00:58:12,120
The radiopharmaceutical is
administered into the patient.

658
00:58:12,120 --> 00:58:15,820
The patient is scanned on, on the machine,

659
00:58:15,820 --> 00:58:18,740
in this case a PET CT scanner and,

660
00:58:18,740 --> 00:58:23,270
and the radiation emitted
is detected by the machine.

661
00:58:23,270 --> 00:58:26,000
So in this case, we have a PET CT scan,

662
00:58:26,000 --> 00:58:27,623
which produces three separate,

663
00:58:27,623 --> 00:58:31,940
three separate sets of
images, a CT scan, a PET scan,

664
00:58:31,940 --> 00:58:34,080
and then a combined CT PET scan.

665
00:58:34,080 --> 00:58:38,480
So these are the most
useful of, of these two,

666
00:58:38,480 --> 00:58:39,863
this set of three images.

667
00:58:39,863 --> 00:58:44,030
And here you can see areas of
increased metabolic activity.

668
00:58:44,030 --> 00:58:47,993
So in this case, we have
a mass in the right hilar,

669
00:58:49,985 --> 00:58:52,210
you know, the right hilar region,

670
00:58:52,210 --> 00:58:54,110
which is likely why the patient

671
00:58:54,110 --> 00:58:55,773
was being imaged in this case.

672
00:58:57,130 --> 00:59:01,040
Additional uses, so here's
an example of a bone scan.

673
00:59:01,040 --> 00:59:04,800
Again the, the agent used for bone scan,

674
00:59:04,800 --> 00:59:07,040
which I review here, it's
called Technetium 99.

675
00:59:07,040 --> 00:59:09,300
You don't have to know that aspect

676
00:59:09,300 --> 00:59:12,700
but it travels to sites of
increased bone turnover.

677
00:59:12,700 --> 00:59:17,230
And as a result, this agent has avidity

678
00:59:17,230 --> 00:59:18,940
for skeletal metastases.

679
00:59:18,940 --> 00:59:21,810
And so here we have an
example of a bone scan

680
00:59:21,810 --> 00:59:23,523
with multiple skeletal metastases.

681
00:59:25,810 --> 00:59:28,720
And then another, another
and probably the most

682
00:59:28,720 --> 00:59:31,590
widely known use in nuclear medicine

683
00:59:31,590 --> 00:59:33,300
is the PET CT scan, which was,

684
00:59:33,300 --> 00:59:35,240
was what we looked at on the first image.

685
00:59:35,240 --> 00:59:38,670
So here we have a PET
CT scan, a fused image

686
00:59:38,670 --> 00:59:40,560
in the coronal plane.

687
00:59:40,560 --> 00:59:44,440
And we have an area of
increased metabolic activity.

688
00:59:44,440 --> 00:59:46,690
It's a mass in the left upper lung.

689
00:59:46,690 --> 00:59:49,140
And we know based on the
increased metabolism,

690
00:59:49,140 --> 00:59:52,550
or we infer, that it
is likely a malignancy.

691
00:59:52,550 --> 00:59:56,490
Malignancies having relative
increased metabolism.

692
00:59:56,490 --> 01:00:00,402
But not all areas on PET CT are areas of,

693
01:00:00,402 --> 01:00:02,900
of abnormal increased metabolism.

694
01:00:02,900 --> 01:00:07,450
Here we have that shown
on this axial plane

695
01:00:07,450 --> 01:00:10,380
showing the outline of the left ventricle,

696
01:00:10,380 --> 01:00:14,793
which is also understandably
hypermetabolic.

697
01:00:17,440 --> 01:00:21,130
And then the last point about PET CT scan,

698
01:00:21,130 --> 01:00:23,440
which is similar to what
we noted in bone scan

699
01:00:23,440 --> 01:00:27,470
is that nuclear medicine takes advantage

700
01:00:27,470 --> 01:00:29,290
of biochemical processes.

701
01:00:29,290 --> 01:00:31,960
In the case of PET CT scan,

702
01:00:31,960 --> 01:00:35,420
the radiopharmaceutical is injected and,

703
01:00:35,420 --> 01:00:39,460
and taken up by, by the cells of interest

704
01:00:39,460 --> 01:00:41,853
in which it is further broken down.

705
01:00:43,180 --> 01:00:48,180
Tumor cells, as we talked about previously

706
01:00:48,630 --> 01:00:51,940
have have a higher metabolic rate compared

707
01:00:51,940 --> 01:00:55,063
to normal cells in most cases.

708
01:00:55,063 --> 01:01:00,063
And, and thus this compound is metabolized

709
01:01:02,280 --> 01:01:04,927
relatively increased by by tumor cells.

710
01:01:04,927 --> 01:01:07,520
And so we'll see a higher concentration

711
01:01:07,520 --> 01:01:09,310
of our radiopharmaceutical

712
01:01:09,310 --> 01:01:13,800
and thereby the radiation
emitted in, in abnormal cells.

713
01:01:13,800 --> 01:01:17,010
And so if we have that
perfectly demonstrated here

714
01:01:17,010 --> 01:01:20,770
with this increased, area
of increased metabolism

715
01:01:20,770 --> 01:01:24,023
in a mass where it doesn't
belong in the leftover lung.

716
01:01:25,950 --> 01:01:29,410
So thank you, questions, if you have any,

717
01:01:29,410 --> 01:01:32,930
you can also send Dmitriy
or myself an email

718
01:01:32,930 --> 01:01:36,150
Dmitriy is gonna start right now.

719
01:01:36,150 --> 01:01:39,860
And again, thank you for being here.

720
01:01:39,860 --> 01:01:43,177
We look forward to
having you in the course.

721
01:03:05,453 --> 01:03:08,320
Dmitriy is getting set up here.

722
01:03:08,320 --> 01:03:12,123
Do you guys have any
questions in the meantime?

723
01:03:19,036 --> 01:03:21,540
- [Woman] I think someone
posted a hypothetical question

724
01:03:21,540 --> 01:03:23,760
about x-rays in the chat.

725
01:03:23,760 --> 01:03:25,430
That seemed kind of interesting.

726
01:03:25,430 --> 01:03:26,810
- [Matthew] Okay, let's see here.

727
01:03:26,810 --> 01:03:28,050
Oh, chat, yep, sorry.

728
01:03:28,050 --> 01:03:29,750
I said I was gonna look at these

729
01:03:29,750 --> 01:03:31,830
and then got carried away.

730
01:03:31,830 --> 01:03:33,110
So we can hear you.

731
01:03:33,110 --> 01:03:35,410
Know anatomic locations
that you described, no.

732
01:03:35,410 --> 01:03:37,590
Are you supposed to know
the anatomic locations?

733
01:03:37,590 --> 01:03:39,203
No, certainly not yet.

734
01:03:42,710 --> 01:03:45,180
I guess that's, that's
the short answer there.

735
01:03:45,180 --> 01:03:46,590
No, don't worry about that yet.

736
01:03:46,590 --> 01:03:51,490
It's, it's merely to, to
illustrate whatever point

737
01:03:51,490 --> 01:03:54,387
I was trying to make,
trying to make about the,

738
01:03:55,235 --> 01:03:58,797
the image modality that,
that I was describing.

739
01:03:58,797 --> 01:04:02,620
Would angiography be performed
in the biplanar suite?

740
01:04:02,620 --> 01:04:03,950
Yep, that's it would.

741
01:04:03,950 --> 01:04:08,660
So in particular cerebral angiography.

742
01:04:08,660 --> 01:04:13,590
And the reason for that
is because localize

743
01:04:13,590 --> 01:04:17,170
in the vessel that you
are trying to opacify

744
01:04:17,170 --> 01:04:19,363
or evaluate, hopefully it's opacified,

745
01:04:20,240 --> 01:04:22,410
although it may not be
and that's why you're

746
01:04:22,410 --> 01:04:24,380
in the cerebral, why one would be

747
01:04:24,380 --> 01:04:26,283
in the cerebral angiography suite.

748
01:04:27,790 --> 01:04:30,560
So, so yes, let's see.

749
01:04:30,560 --> 01:04:31,680
Weird theoretic.

750
01:04:31,680 --> 01:04:35,980
So question, it's not a weird
question, so don't worry.

751
01:04:35,980 --> 01:04:38,790
Is the layout of the CT scanner source

752
01:04:38,790 --> 01:04:41,960
and detector similar
enough to standard 2D x-ray

753
01:04:41,960 --> 01:04:45,310
that one would be able
to simulate a 2D x-ray

754
01:04:45,310 --> 01:04:47,993
from a stationary CT scanner?

755
01:04:50,415 --> 01:04:53,960
Let's, let's come, I'll remember that.

756
01:04:53,960 --> 01:04:55,670
I'll take that question down

757
01:04:55,670 --> 01:04:57,710
and I'll answer it in the next lectures.

758
01:04:57,710 --> 01:04:59,840
'Cause Dmitriy is ready to get started.

759
01:04:59,840 --> 01:05:02,620
So I'm, I'm going to, and
there are two more here,

760
01:05:02,620 --> 01:05:06,700
so I will write those
down and I'll answer them

761
01:05:06,700 --> 01:05:09,170
in the next lecture, if that's okay,

762
01:05:09,170 --> 01:05:11,040
which will be Wednesday
and I'll sign off here

763
01:05:11,040 --> 01:05:12,523
and let Dmitriy get started.

764
01:05:37,330 --> 01:05:39,050
- [Dmitriy] Everybody this is Dmitriy.

765
01:05:39,050 --> 01:05:40,100
Can you guys hear me?

766
01:05:43,340 --> 01:05:44,710
- [Student] Yeah, we can hear you.

767
01:05:44,710 --> 01:05:46,003
- [Dmitriy] Okay, great, thank you.

768
01:05:47,500 --> 01:05:52,500
Sorry, I got held up by some
clinical patient care issues.

769
01:05:53,380 --> 01:05:56,173
I'm gonna start up my PowerPoint here.

770
01:06:02,070 --> 01:06:05,610
I was hoping to get an
ultrasound machine in here

771
01:06:05,610 --> 01:06:09,280
to show you guys how it works,

772
01:06:09,280 --> 01:06:13,143
but I'm not sure that's gonna be.

773
01:06:15,010 --> 01:06:16,243
Well, I couldn't get it (laughs)

774
01:06:16,243 --> 01:06:17,933
I just got held up.

775
01:06:19,320 --> 01:06:24,320
So here's my screen.

776
01:06:30,660 --> 01:06:31,533
Let's see.

777
01:06:34,580 --> 01:06:39,170
Okay, do you guys see my PowerPoint here?

778
01:06:39,170 --> 01:06:40,070
Just to make sure.

779
01:06:40,960 --> 01:06:41,793
- [Student] Yeah, we can see it.

780
01:06:41,793 --> 01:06:42,830
- [Dmitriy] Okay, great, thank you.

781
01:06:42,830 --> 01:06:44,830
Okay so (clears throat)

782
01:06:44,830 --> 01:06:47,300
Welcome everybody, I'm Dmitriy Axelrod.

783
01:06:47,300 --> 01:06:50,723
I'm the co-director of this course.

784
01:06:51,970 --> 01:06:55,601
Hopefully you had a great
time with Dr. Geeslin

785
01:06:55,601 --> 01:06:59,980
and that he's shown you how
you can make some mutations

786
01:06:59,980 --> 01:07:03,070
with our radiation and such.

787
01:07:03,070 --> 01:07:05,720
This will be something
completely different.

788
01:07:05,720 --> 01:07:09,563
We will look at some non-radiation,

789
01:07:10,790 --> 01:07:14,180
non-ionizing radiation
based imaging techniques.

790
01:07:14,180 --> 01:07:17,030
So we'll start with ultrasound.

791
01:07:17,030 --> 01:07:22,030
So the way that ultrasound
works is different

792
01:07:23,180 --> 01:07:27,130
from the x-rays that you
were talking about earlier

793
01:07:27,130 --> 01:07:28,090
and nuclear medicine,

794
01:07:28,090 --> 01:07:30,140
which is on the electromagnetic spectrum.

795
01:07:31,420 --> 01:07:36,140
We work in the ultrasound
or the sound spectrum,

796
01:07:36,140 --> 01:07:38,820
and the sound spectrum here is described,

797
01:07:38,820 --> 01:07:41,490
infrasound, acoustic
sound, which is the sound

798
01:07:41,490 --> 01:07:43,480
that we can actually hear, ultrasound,

799
01:07:43,480 --> 01:07:45,350
which is sound above what we can hear.

800
01:07:45,350 --> 01:07:47,720
It goes anything above 20 Hertz.

801
01:07:47,720 --> 01:07:52,490
So for humans, anything between 20 Hertz

802
01:07:52,490 --> 01:07:55,500
and 20 kilohertz is a acoustic sound.

803
01:07:55,500 --> 01:07:59,250
And so while the
electromagnetic spectrum is,

804
01:07:59,250 --> 01:08:04,008
describes the moving,
movement of charge particles,

805
01:08:04,008 --> 01:08:08,020
sound as a mechanical
energy disturbance of,

806
01:08:08,020 --> 01:08:10,690
of a medium, and in the
case of audible sound,

807
01:08:10,690 --> 01:08:11,980
the medium is air.

808
01:08:11,980 --> 01:08:15,358
So it's mechanical disturbance
of air that we are,

809
01:08:15,358 --> 01:08:19,560
our eardrums, are able to hear as sound.

810
01:08:19,560 --> 01:08:23,420
So again, ultrasound is
anything that's above audible

811
01:08:23,420 --> 01:08:26,233
or above 20 kilhertz here.

812
01:08:27,880 --> 01:08:29,790
So why is ultrasound important?

813
01:08:29,790 --> 01:08:31,543
Why is it so, so amazing?

814
01:08:32,552 --> 01:08:35,320
And it's certainly come, come a long way,

815
01:08:35,320 --> 01:08:38,500
but the important thing about
ultrasound is that it's,

816
01:08:38,500 --> 01:08:40,320
no ionizing radiation is used

817
01:08:41,260 --> 01:08:44,743
and in the diagnostic range
of frequencies of ultrasound,

818
01:08:45,730 --> 01:08:48,740
there is no soft tissue damage at all.

819
01:08:48,740 --> 01:08:51,473
And we'll talk about
safety a little bit later.

820
01:08:52,320 --> 01:08:54,920
The other thing about ultrasound
is that it's real timing

821
01:08:54,920 --> 01:08:57,680
that as we're scanning, we're seeing what,

822
01:08:57,680 --> 01:09:00,210
what is happening in the patient,

823
01:09:00,210 --> 01:09:03,110
and we can adjust our scanning parameters

824
01:09:03,110 --> 01:09:04,880
or adjust where we're scanning based

825
01:09:04,880 --> 01:09:06,680
on what we're seeing right away,

826
01:09:06,680 --> 01:09:09,120
instead of a, more of a shotgun approach

827
01:09:09,120 --> 01:09:12,890
with something like CT or, or x-ray

828
01:09:12,890 --> 01:09:14,560
where we're just imaging an entire area

829
01:09:14,560 --> 01:09:16,540
and trying to figure out
what we, what we see.

830
01:09:16,540 --> 01:09:18,220
Here in ultrasound, we
pick what we wanna see

831
01:09:18,220 --> 01:09:21,193
and we try to see the
best we can in real time.

832
01:09:22,180 --> 01:09:24,940
And over the last many years,

833
01:09:24,940 --> 01:09:26,650
it has become much more portable.

834
01:09:26,650 --> 01:09:30,590
As you can see here, there
are handheld wifi probes

835
01:09:30,590 --> 01:09:33,150
that you can take
anywhere, anywhere you want

836
01:09:33,150 --> 01:09:34,730
as long as you have a cell phone.

837
01:09:34,730 --> 01:09:39,170
And so it has made
ultrasound very accessible,

838
01:09:39,170 --> 01:09:44,100
relatively inexpensive,
and really ubiquitous,

839
01:09:44,100 --> 01:09:46,870
including something called
point of care ultrasound,

840
01:09:46,870 --> 01:09:51,370
which is where a non radiologists
are able to use ultrasound

841
01:09:52,270 --> 01:09:55,560
in their clinics or in
the ER, to make diagnoses,

842
01:09:55,560 --> 01:09:58,840
without having to involve
the Department of Radiology,

843
01:09:58,840 --> 01:10:01,570
which in some cases is, is good

844
01:10:01,570 --> 01:10:04,620
and in some cases is questionable.

845
01:10:04,620 --> 01:10:07,520
But a very important
diagnostic tool, nevertheless,

846
01:10:07,520 --> 01:10:08,820
with appropriate training.

847
01:10:10,480 --> 01:10:13,080
So this is kind of one of the images

848
01:10:13,080 --> 01:10:17,090
of early ultrasound
equipment, as you can see.

849
01:10:17,090 --> 01:10:21,430
Not terribly portable, and
this was done as an experiment

850
01:10:21,430 --> 01:10:22,800
in a, in a water bath.

851
01:10:22,800 --> 01:10:24,740
And the reason there's a water bath is

852
01:10:24,740 --> 01:10:26,700
because you need to have a medium

853
01:10:26,700 --> 01:10:28,800
for the mechanical, you know,

854
01:10:28,800 --> 01:10:31,210
energy disturbance to happen in.

855
01:10:31,210 --> 01:10:32,860
And we'll kinda get into
that in just a second

856
01:10:32,860 --> 01:10:35,633
about why you need to have
some kind of a medium.

857
01:10:37,940 --> 01:10:41,083
So what are some physical
concepts in ultrasound?

858
01:10:42,820 --> 01:10:45,480
Sound can't exist without a medium,

859
01:10:45,480 --> 01:10:48,833
and that's why in a vacuum, you can not,

860
01:10:50,630 --> 01:10:52,850
there is no audible sound.

861
01:10:52,850 --> 01:10:57,850
And so it's produced again
by mechanical disturbance

862
01:10:58,110 --> 01:10:59,993
of the particles in that medium.

863
01:11:00,850 --> 01:11:02,890
And it's, you know, it's a transfer

864
01:11:02,890 --> 01:11:06,020
of kinetic energy when
that disturbance occurs.

865
01:11:06,020 --> 01:11:07,540
So this transfer of energy results

866
01:11:07,540 --> 01:11:10,120
in alternating compression and refraction

867
01:11:10,120 --> 01:11:12,050
of the particles in that medium

868
01:11:12,050 --> 01:11:15,350
as the sound wave
propagates within the medium

869
01:11:16,190 --> 01:11:20,170
and diagnostic ultrasound
operates at anywhere

870
01:11:20,170 --> 01:11:21,960
between one and 20 megahertz.

871
01:11:21,960 --> 01:11:24,780
And you remember anything
above 20 kiloshertz

872
01:11:24,780 --> 01:11:28,203
is above audible sound so ultrasound.

873
01:11:30,480 --> 01:11:32,850
This graphic doesn't seem working

874
01:11:32,850 --> 01:11:35,620
but a transverse wave is
one that goes like this,

875
01:11:35,620 --> 01:11:37,430
which is what this is.

876
01:11:37,430 --> 01:11:41,920
And longitudinal wave is
basically a compression of the,

877
01:11:41,920 --> 01:11:46,620
of this spring, ya know, closer
together and further apart.

878
01:11:46,620 --> 01:11:51,620
And so this graphic here
shows that in here there's a,

879
01:11:52,790 --> 01:11:56,390
there's a progression
or sorry, compression,

880
01:11:56,390 --> 01:11:58,960
and here there's, there's rare fraction.

881
01:11:58,960 --> 01:12:01,788
So here you can see the particles
are coming closer together

882
01:12:01,788 --> 01:12:04,150
and they're coming further apart here.

883
01:12:04,150 --> 01:12:06,200
And so as the sound propagates,

884
01:12:06,200 --> 01:12:09,363
it keeps causing this
compression in rare fraction.

885
01:12:13,470 --> 01:12:17,520
So how do we generate an ultrasound image?

886
01:12:17,520 --> 01:12:22,380
So the transducer that we
use transmits sound waves

887
01:12:22,380 --> 01:12:25,230
into the body and the sound
waves are reflected off

888
01:12:25,230 --> 01:12:27,110
of the different interfaces inside,

889
01:12:27,110 --> 01:12:29,010
that it meets inside the body.

890
01:12:29,010 --> 01:12:31,927
And then when it meets these interfaces,

891
01:12:31,927 --> 01:12:33,990
the sound bounces off and comes back

892
01:12:33,990 --> 01:12:35,750
and returns to the transducer.

893
01:12:35,750 --> 01:12:39,690
And that's how we see
what's happening inside.

894
01:12:39,690 --> 01:12:42,800
And then an image uses, the
information is then used,

895
01:12:42,800 --> 01:12:45,660
to create an image based on
what sound waves come back

896
01:12:45,660 --> 01:12:46,623
to the transducer.

897
01:12:50,615 --> 01:12:55,030
So the first part where the
transducer transmits sound

898
01:12:55,030 --> 01:12:56,960
or pressure waves into the body.

899
01:12:56,960 --> 01:12:59,910
And so the way that works inside the probe

900
01:12:59,910 --> 01:13:01,660
is that the electricity is applied

901
01:13:01,660 --> 01:13:03,870
to something called a
piezoelectric crystal

902
01:13:03,870 --> 01:13:06,630
and piezo means in Greek pressure,

903
01:13:06,630 --> 01:13:11,260
electric from the word electrum or amber,

904
01:13:11,260 --> 01:13:13,350
because when you, if you were,
apparently if you rub amber,

905
01:13:13,350 --> 01:13:14,950
it causes an electrostatic phenomenon

906
01:13:14,950 --> 01:13:17,730
so that's where the
word electric came from.

907
01:13:17,730 --> 01:13:20,300
And then most natural crystal,

908
01:13:20,300 --> 01:13:22,635
and that's what was used originally

909
01:13:22,635 --> 01:13:26,040
in ultrasound probes is quartz, but it's,

910
01:13:26,040 --> 01:13:28,760
it's very difficult to
use because you have

911
01:13:28,760 --> 01:13:30,250
to shape it appropriately.

912
01:13:30,250 --> 01:13:33,940
And so now ultrasound probes
use man-made materials

913
01:13:33,940 --> 01:13:36,850
to improve the performance of the crystal.

914
01:13:36,850 --> 01:13:40,360
And that's why the
ultrasound probes that we,

915
01:13:40,360 --> 01:13:42,960
that come along with the machine
are very, very expensive.

916
01:13:42,960 --> 01:13:44,417
Some of the probes are
up to, you know, 15,

917
01:13:44,417 --> 01:13:47,160
$20,000 just for the probe.

918
01:13:47,160 --> 01:13:49,410
That's not even including
the machine itself.

919
01:13:50,250 --> 01:13:52,483
So those, those crystals
are very expensive.

920
01:13:54,050 --> 01:13:56,020
So what happens is the alternate current,

921
01:13:56,020 --> 01:13:58,510
alternating current is
applied to the crystals,

922
01:13:58,510 --> 01:14:01,670
which results in vibration
of those crystals

923
01:14:01,670 --> 01:14:03,850
and the vibration applies mechanical,

924
01:14:03,850 --> 01:14:05,820
results in the mechanical pressure

925
01:14:05,820 --> 01:14:08,500
or a pressure wave that is exerted

926
01:14:08,500 --> 01:14:10,590
onto the adjacent body part.

927
01:14:10,590 --> 01:14:15,590
So the, the wave is produced by vibration

928
01:14:15,830 --> 01:14:19,453
of those crystals on the skin.

929
01:14:21,900 --> 01:14:23,830
And so then the sound
waves are reflected off

930
01:14:23,830 --> 01:14:27,240
of the interfaces and then when they,

931
01:14:27,240 --> 01:14:29,850
when they reach, ya know,
various organs inside the body

932
01:14:29,850 --> 01:14:32,350
and then the sound waves
return to the transducer

933
01:14:33,210 --> 01:14:35,730
and then the, this
piezoelectric crystal works

934
01:14:35,730 --> 01:14:38,050
in the opposite way and converts the,

935
01:14:38,050 --> 01:14:39,640
the pressure energy or
the mechanical electric

936
01:14:39,640 --> 01:14:41,960
that comes back from the
body to the transducer,

937
01:14:41,960 --> 01:14:46,200
converts it to electrical AC current.

938
01:14:46,200 --> 01:14:48,430
And then the AC current is
what goes back to the machine

939
01:14:48,430 --> 01:14:51,637
and tells the machine what
the probe is, quote unquote,

940
01:14:51,637 --> 01:14:53,203
"seeing" inside the body.

941
01:14:54,080 --> 01:14:58,853
So these crystals work in both
ways, forward and backwards.

942
01:15:02,930 --> 01:15:06,600
So the image is generated based

943
01:15:06,600 --> 01:15:09,730
on when the returning waves are received

944
01:15:09,730 --> 01:15:11,663
or heard by the transducer.

945
01:15:12,590 --> 01:15:16,750
So the structures are
displaced closer to the probe.

946
01:15:16,750 --> 01:15:19,360
So here is what we call
the footprint of the probe.

947
01:15:19,360 --> 01:15:21,560
This is a curved probe here.

948
01:15:21,560 --> 01:15:26,483
And if a object is really
close to the probe,

949
01:15:27,330 --> 01:15:30,330
the sound wave being reflected off

950
01:15:30,330 --> 01:15:33,060
of that object will return sooner.

951
01:15:33,060 --> 01:15:36,183
And so this scalp of this little baby,

952
01:15:37,290 --> 01:15:39,620
the sound off the scalp,
reflecting off the scalp,

953
01:15:39,620 --> 01:15:41,140
return to transducer first.

954
01:15:41,140 --> 01:15:43,060
And that's why the scalp is first

955
01:15:43,060 --> 01:15:45,580
in the image closest to the transducer.

956
01:15:45,580 --> 01:15:48,370
And the further away we go,
when we get to the ventricles

957
01:15:48,370 --> 01:15:52,200
of this head, you know,
the further out we go,

958
01:15:52,200 --> 01:15:56,100
the longer any of these
echoes took to get back

959
01:15:56,100 --> 01:15:58,830
through the transducer
after being admitted.

960
01:15:58,830 --> 01:16:01,220
And so, again, the structures
are displayed closer

961
01:16:01,220 --> 01:16:03,160
to the probe were the first waves

962
01:16:03,160 --> 01:16:04,970
to return back to the probe

963
01:16:04,970 --> 01:16:07,020
and the structures are displayed farther,

964
01:16:08,180 --> 01:16:10,510
farthest on the image from the probe,

965
01:16:10,510 --> 01:16:12,123
were the last waves to
return back to the probe.

966
01:16:12,123 --> 01:16:15,650
And you can see, you
know, sort of the fidelity

967
01:16:15,650 --> 01:16:18,050
of the closer structures is
much better than fidelity

968
01:16:18,050 --> 01:16:18,883
of the farther structures,

969
01:16:18,883 --> 01:16:22,860
because many more sound
waves get bounced off here,

970
01:16:22,860 --> 01:16:24,540
than the ones that get
bounced off back here,

971
01:16:24,540 --> 01:16:27,883
because there weren't as many
left anymore to bounce back.

972
01:16:31,360 --> 01:16:34,883
So, so what's the importance
of the ultrasound gel?

973
01:16:36,620 --> 01:16:37,453
And if any of you have had an ultrasound,

974
01:16:37,453 --> 01:16:40,163
you know, you get covered
in this goopy stuff,

975
01:16:41,010 --> 01:16:45,670
and what it does is it
prevents any air gaps

976
01:16:45,670 --> 01:16:50,390
between the probe and the, the body,

977
01:16:50,390 --> 01:16:52,870
because when, when the sound beam

978
01:16:52,870 --> 01:16:55,330
or the sound pulse,
encounters an interface

979
01:16:55,330 --> 01:16:58,090
of two materials which
have a large difference

980
01:16:58,090 --> 01:17:00,490
in their propagation velocity,

981
01:17:00,490 --> 01:17:02,780
most or all of the beam
ends up being reflected.

982
01:17:02,780 --> 01:17:05,890
So between the probe and the air,

983
01:17:05,890 --> 01:17:08,470
there's a very large difference
in propagation velocity

984
01:17:08,470 --> 01:17:11,070
and so most the sound
beam will get reflected

985
01:17:11,070 --> 01:17:14,090
right back to the probe
so you get no information.

986
01:17:14,090 --> 01:17:19,090
So if you don't put gel
between the probe and the skin,

987
01:17:19,480 --> 01:17:21,047
all the air that gets
trapped between the probe

988
01:17:21,047 --> 01:17:23,217
and the skin will reflect
a lot of the sound beam

989
01:17:23,217 --> 01:17:26,020
and so you have very poor image.

990
01:17:26,020 --> 01:17:28,990
The gel kind of matches the difference

991
01:17:28,990 --> 01:17:33,216
between the propagation velocity of the,

992
01:17:33,216 --> 01:17:36,380
of the probe and the propagation
velocity of the body.

993
01:17:36,380 --> 01:17:38,820
And so all the sound beam,

994
01:17:38,820 --> 01:17:40,310
or as much of the som beam as possible,

995
01:17:40,310 --> 01:17:45,310
gets from the probe
into the, into the body.

996
01:17:46,710 --> 01:17:49,640
And so, and this is because
of acoustic impedance,

997
01:17:49,640 --> 01:17:52,530
which is, which is dependent
on this propagation velocity.

998
01:17:52,530 --> 01:17:54,520
And we're not gonna really
discuss acoustic impedance here.

999
01:17:54,520 --> 01:17:56,713
It's, it's too in depth.

1000
01:17:58,150 --> 01:18:01,530
So the gel, again, it eliminates
that large velocity change

1001
01:18:01,530 --> 01:18:03,387
caused by air between probe and skin.

1002
01:18:03,387 --> 01:18:07,220
So you can see the propagation
velocity of air is 330

1003
01:18:07,220 --> 01:18:10,150
whereas most of our sort of soft tissues

1004
01:18:10,150 --> 01:18:12,010
are in the 1500 range.

1005
01:18:12,010 --> 01:18:13,917
So that's too much of a difference

1006
01:18:13,917 --> 01:18:18,393
and so most of the sound
wave would be reflected.

1007
01:18:20,350 --> 01:18:25,350
All right, so this is hopefully gonna work

1008
01:18:26,810 --> 01:18:31,470
and will allow us, or allow
me, to use Dr. YouTube

1009
01:18:31,470 --> 01:18:36,060
to show you guys the concepts
we just discussed graphically.

1010
01:18:36,060 --> 01:18:37,260
Let's see if this works.

1011
01:18:40,082 --> 01:18:42,582
(faint music)

1012
01:18:47,743 --> 01:18:50,004
Let me see if I can fast forward here.

1013
01:18:50,004 --> 01:18:52,504
(faint music)

1014
01:18:58,700 --> 01:19:00,530
- [Narrator] The heart of
most ultrasound systems

1015
01:19:00,530 --> 01:19:02,400
is a device called a transducer,

1016
01:19:02,400 --> 01:19:05,005
which uses an array of
piezoelectric crystals.

1017
01:19:05,005 --> 01:19:06,590
- [Dmitriy] So here's
one wave of crystals.

1018
01:19:06,590 --> 01:19:08,840
- [Narrator] Vibrates when an
electric signal is applied,

1019
01:19:08,840 --> 01:19:11,320
producing high frequency
sound pressure waves,

1020
01:19:11,320 --> 01:19:13,480
which we call ultrasound.

1021
01:19:13,480 --> 01:19:14,313
- [Dmitriy] Before I go on,

1022
01:19:14,313 --> 01:19:16,243
can you guys hear the captioning or no?

1023
01:19:17,730 --> 01:19:18,630
- [Student] Yeah, we can.

1024
01:19:18,630 --> 01:19:19,880
- [Dmitriy] Okay, good I was.

1025
01:19:19,880 --> 01:19:20,880
Otherwise I could do it.

1026
01:19:20,880 --> 01:19:22,230
Okay, here we go.

1027
01:19:22,230 --> 01:19:24,670
- [Narrator] More importantly,
this type of crystal

1028
01:19:24,670 --> 01:19:26,470
can also work in reverse.

1029
01:19:26,470 --> 01:19:28,360
It can produce electrical signals

1030
01:19:28,360 --> 01:19:30,480
when it detects high-frequency
sound pressure waves.

1031
01:19:30,480 --> 01:19:34,330
When a transducer directs
ultrasound waves into the body,

1032
01:19:34,330 --> 01:19:35,590
they pass right through the skin

1033
01:19:35,590 --> 01:19:37,840
and into the internal anatomy.

1034
01:19:37,840 --> 01:19:39,300
As the waves encounter tissues

1035
01:19:39,300 --> 01:19:41,460
with different
characteristics and densities,

1036
01:19:41,460 --> 01:19:43,210
they produce echoes that reflect back

1037
01:19:43,210 --> 01:19:45,010
to the piezoelectric crystal.

1038
01:19:45,010 --> 01:19:47,560
This happens more than a
thousand times a second.

1039
01:19:47,560 --> 01:19:49,990
Return echoes are converted
to electric signals,

1040
01:19:49,990 --> 01:19:52,080
which a computer converts
into points of brightness

1041
01:19:52,080 --> 01:19:54,900
on the image corresponding
to the anatomic position

1042
01:19:54,900 --> 01:19:57,230
and the strength of the reflective echoes.

1043
01:19:57,230 --> 01:19:59,980
A medical transducer contains
a larger way of crystals,

1044
01:19:59,980 --> 01:20:02,030
which allow it to make
a series of image lines

1045
01:20:02,030 --> 01:20:06,200
that together form a complete
image frame called a sonogram.

1046
01:20:06,200 --> 01:20:08,970
In addition, all the crystals
are repeatedly activated

1047
01:20:08,970 --> 01:20:11,650
many times in such a way
that a complete image frame

1048
01:20:11,650 --> 01:20:13,923
is formed around 20 times per second.

1049
01:20:14,890 --> 01:20:16,450
- [Dmitriy] All right so
get, that gives the idea

1050
01:20:16,450 --> 01:20:19,590
of basically what I talked about 15 years,

1051
01:20:19,590 --> 01:20:24,550
15 minutes in less than a
minute, which begs the question,

1052
01:20:24,550 --> 01:20:27,960
why don't you just watch
YouTube videos to learn anatomy?

1053
01:20:27,960 --> 01:20:31,950
And I don't have a good
answer to that question.

1054
01:20:31,950 --> 01:20:34,483
But let's move on, so probe selection.

1055
01:20:35,780 --> 01:20:38,050
So again, these are the
probes I was discussing.

1056
01:20:38,050 --> 01:20:42,040
There are different types,
some are external probes.

1057
01:20:42,040 --> 01:20:44,190
So this is the curvilinear
probe, I mentioned.

1058
01:20:44,190 --> 01:20:45,970
This is a linear probe.

1059
01:20:45,970 --> 01:20:48,820
This is what we call a hockey stick probe.

1060
01:20:48,820 --> 01:20:51,620
And I think it's called a
hockey stick all over the world,

1061
01:20:51,620 --> 01:20:55,730
not just in Vermont, because
of our hockey history,

1062
01:20:55,730 --> 01:21:00,210
but this one here is called
an intracavitary probe.

1063
01:21:00,210 --> 01:21:02,140
So this is an endovaginal probe.

1064
01:21:02,140 --> 01:21:05,550
So this allows us to
see things like uterus

1065
01:21:05,550 --> 01:21:09,410
and ovaries much better by
doing transvaginal ultrasound.

1066
01:21:09,410 --> 01:21:12,240
And depending on which probe you use,

1067
01:21:12,240 --> 01:21:15,010
the profile of the sound
beam is gonna be different.

1068
01:21:15,010 --> 01:21:18,240
So for example, here in a
lineary probe, you know,

1069
01:21:18,240 --> 01:21:20,740
the sounds comes out just straight out,

1070
01:21:20,740 --> 01:21:24,050
whereas in a curvilinear
probe, it comes out at an angle

1071
01:21:24,050 --> 01:21:27,440
and so you see a lot more
of the body than you would

1072
01:21:27,440 --> 01:21:28,770
with a linear probe.

1073
01:21:28,770 --> 01:21:30,210
Whereas with a phased-array probe,

1074
01:21:30,210 --> 01:21:32,853
you have one focal point of,

1075
01:21:34,038 --> 01:21:38,030
of where the crystal emanates its beam

1076
01:21:38,030 --> 01:21:41,660
and it gets fanned out and then comes back

1077
01:21:41,660 --> 01:21:43,910
in the same fanned out way to the probe.

1078
01:21:43,910 --> 01:21:45,600
And so you're able to get, for example,

1079
01:21:45,600 --> 01:21:47,980
between the ribs with
this phased-array probe,

1080
01:21:47,980 --> 01:21:50,010
but you won't have as much
resolution as you would

1081
01:21:50,010 --> 01:21:51,693
with a curvilinear
probe or a linear probe.

1082
01:21:53,567 --> 01:21:55,557
So you're gonna have a harder time seeing.

1083
01:21:57,166 --> 01:21:58,930
Okay, this is a different type of a probe.

1084
01:21:58,930 --> 01:22:02,446
This is from endoscopists.

1085
01:22:02,446 --> 01:22:07,340
So a gastroenterologist can go in and do,

1086
01:22:07,340 --> 01:22:10,360
you know, do endoscopy,
take a look at the stomach,

1087
01:22:10,360 --> 01:22:11,940
take a look at the duodenum

1088
01:22:11,940 --> 01:22:14,880
and then they can use an ultrasound

1089
01:22:14,880 --> 01:22:17,470
through the same endoscope here to look

1090
01:22:17,470 --> 01:22:19,480
at the pancreas because
you can't see the pancreas

1091
01:22:19,480 --> 01:22:20,870
from the lumen of the stomach,

1092
01:22:20,870 --> 01:22:22,940
but they can look at the
pancreas through the wall

1093
01:22:22,940 --> 01:22:24,980
of the stomach and if they need to,

1094
01:22:24,980 --> 01:22:26,780
they can biopsy a pancreatic cancer

1095
01:22:26,780 --> 01:22:30,380
or any kind of pancreatic
mass with this needle here

1096
01:22:30,380 --> 01:22:32,660
that is guided by the ultrasound machine.

1097
01:22:32,660 --> 01:22:35,110
So this is what the
gastroenterologists can do

1098
01:22:36,010 --> 01:22:37,403
in their endoscopy suite.

1099
01:22:38,330 --> 01:22:39,810
This is a transrectal probe

1100
01:22:39,810 --> 01:22:42,080
and urologists use transrectal probes

1101
01:22:42,080 --> 01:22:45,520
to guide their biopsies
of the prostate gland.

1102
01:22:45,520 --> 01:22:49,650
And so this is another utility,

1103
01:22:49,650 --> 01:22:53,180
and unfortunately there are
a lot of prostate biopsies,

1104
01:22:53,180 --> 01:22:54,910
which are very uncomfortable,

1105
01:22:54,910 --> 01:22:56,910
but are needed to look
for prostate cancer.

1106
01:22:56,910 --> 01:23:00,520
So you can see, this is
a needle here that goes

1107
01:23:00,520 --> 01:23:02,550
into the prostate gland here

1108
01:23:02,550 --> 01:23:05,000
and the ultrasound machine here,

1109
01:23:05,000 --> 01:23:06,660
the probe is right up against the rectum,

1110
01:23:06,660 --> 01:23:09,990
imaging the prostate,
and guiding this needle

1111
01:23:09,990 --> 01:23:12,833
into where you want to
biopsy the prostate gland.

1112
01:23:15,550 --> 01:23:18,440
So when you select the probe,

1113
01:23:18,440 --> 01:23:20,647
you look at the profile of the probe,

1114
01:23:20,647 --> 01:23:23,900
but you also look at the
frequency of the probe.

1115
01:23:23,900 --> 01:23:27,400
And so the lower the probe frequency,

1116
01:23:27,400 --> 01:23:29,960
the deeper the penetration
of the sound beam

1117
01:23:29,960 --> 01:23:31,420
into the soft tissues,

1118
01:23:31,420 --> 01:23:32,750
but you get lower resolution.

1119
01:23:32,750 --> 01:23:34,070
If you remember, I showed you in that,

1120
01:23:34,070 --> 01:23:36,870
in that little baby head,
the farther that things were

1121
01:23:36,870 --> 01:23:39,932
the more, the less clear they became.

1122
01:23:39,932 --> 01:23:42,060
And so if you think about it,

1123
01:23:42,060 --> 01:23:44,750
well, so then the high frequency probe

1124
01:23:44,750 --> 01:23:46,640
won't penetrate as deeply,

1125
01:23:46,640 --> 01:23:48,150
but you will have much better resolution

1126
01:23:48,150 --> 01:23:50,240
of all those things that
are just under the probe.

1127
01:23:50,240 --> 01:23:53,580
So you'll see things much
better that are nearby.

1128
01:23:53,580 --> 01:23:57,090
And if you think about it,
let's say you lived in a,

1129
01:23:57,090 --> 01:23:58,460
you know, in a house or
an apartment building,

1130
01:23:58,460 --> 01:24:01,390
and you had a neighbor who was playing

1131
01:24:01,390 --> 01:24:03,910
some really loud music,

1132
01:24:03,910 --> 01:24:06,160
for the most part what
you will hear is that,

1133
01:24:07,160 --> 01:24:09,267
is the deep bass, sort of
the, if you think of what,

1134
01:24:09,267 --> 01:24:11,600
you know, I don't know
dubstep or something,

1135
01:24:11,600 --> 01:24:13,710
and, and you hear the bass,

1136
01:24:13,710 --> 01:24:14,940
but you won't really hear the treble

1137
01:24:14,940 --> 01:24:17,660
because that's the high-frequency
portion of the music.

1138
01:24:17,660 --> 01:24:21,310
So the low frequency, those bass sounds,

1139
01:24:21,310 --> 01:24:22,940
will penetrate deeper and will penetrate

1140
01:24:22,940 --> 01:24:25,240
through the walls and
into your own apartment.

1141
01:24:28,170 --> 01:24:31,450
Okay, so here are some images
generated by various probes.

1142
01:24:31,450 --> 01:24:34,120
So here are two linear probes here.

1143
01:24:34,120 --> 01:24:35,980
This is the linear probe
I was telling you about

1144
01:24:35,980 --> 01:24:38,260
that had the flat face, like this,

1145
01:24:38,260 --> 01:24:41,030
and shot the beam straight out.

1146
01:24:41,030 --> 01:24:44,320
You can also do some fancy electrical work

1147
01:24:44,320 --> 01:24:47,170
and activate these little crystals in a,

1148
01:24:47,170 --> 01:24:50,620
at a different time point and
that helps you steer the beam.

1149
01:24:50,620 --> 01:24:53,963
So even though it's a linear probe,

1150
01:24:54,800 --> 01:24:58,230
based on how the sound
beams are interacting

1151
01:24:58,230 --> 01:25:02,113
with each other, it steers the
beam to one side or another.

1152
01:25:03,070 --> 01:25:05,170
Here's another probe that's also linear,

1153
01:25:05,170 --> 01:25:07,660
but it has a profile like
the curvilinear probe.

1154
01:25:07,660 --> 01:25:09,943
And again, that's based on how,

1155
01:25:11,130 --> 01:25:13,680
the way that these crystals get activated.

1156
01:25:13,680 --> 01:25:16,430
And that's, you know, this is
not important for this class,

1157
01:25:16,430 --> 01:25:19,600
but just more point of
interest that you can do

1158
01:25:19,600 --> 01:25:24,200
fancy things with, with
what you have at baseline.

1159
01:25:24,200 --> 01:25:26,360
And here's a curvilinear probe,

1160
01:25:26,360 --> 01:25:30,430
and you can see that the
kind of the resolution here

1161
01:25:30,430 --> 01:25:32,280
in the linear probe is
trying to do fancy things

1162
01:25:32,280 --> 01:25:33,880
to imitate a curvilinear probe.

1163
01:25:33,880 --> 01:25:36,050
The resolution here is not as good as

1164
01:25:36,050 --> 01:25:38,565
with the curvilinear probe here.

1165
01:25:38,565 --> 01:25:39,930
And also you have to look at, you know,

1166
01:25:39,930 --> 01:25:41,500
this is the frequency of the probe.

1167
01:25:41,500 --> 01:25:43,800
So this is a higher frequency probe.

1168
01:25:43,800 --> 01:25:46,270
So it'll have nicer images nearby.

1169
01:25:46,270 --> 01:25:49,370
Remember the higher,
higher the frequency the,

1170
01:25:49,370 --> 01:25:51,690
the less deep the penetration,

1171
01:25:51,690 --> 01:25:54,250
but you'll have a better
resolution nearby.

1172
01:25:54,250 --> 01:25:56,997
Whereas this probe can penetrate deeper

1173
01:25:56,997 --> 01:25:59,350
and you can see deeper
structures much better.

1174
01:25:59,350 --> 01:26:01,040
You can see this aorta here,

1175
01:26:01,040 --> 01:26:02,880
much better than the aorta here.

1176
01:26:02,880 --> 01:26:04,130
This is the same patient.

1177
01:26:05,513 --> 01:26:07,710
And this is a sector
probe and the sector probe

1178
01:26:07,710 --> 01:26:10,140
remember I said it's, it's
got a small footprint.

1179
01:26:10,140 --> 01:26:11,294
It's a, it's a really small probe.

1180
01:26:11,294 --> 01:26:13,410
You can get into tight spaces with it,

1181
01:26:13,410 --> 01:26:14,830
but the resolution isn't gonna be as good,

1182
01:26:14,830 --> 01:26:16,660
because it's trying to do a lot of things

1183
01:26:16,660 --> 01:26:18,113
with a very small footprint.

1184
01:26:21,390 --> 01:26:24,250
All right, so let's move
on to safety of ultrasound.

1185
01:26:24,250 --> 01:26:26,550
And I'm gonna try to go
a little bit faster here,

1186
01:26:26,550 --> 01:26:28,666
because this is all very interesting,

1187
01:26:28,666 --> 01:26:30,610
but we have to talk about MRI still.

1188
01:26:30,610 --> 01:26:34,670
So again, no ionizing radiation.

1189
01:26:34,670 --> 01:26:38,540
So there is no cell or gene disruption

1190
01:26:38,540 --> 01:26:40,731
with ultrasound, thankfully,

1191
01:26:40,731 --> 01:26:43,840
in the, in the diagnostic range,

1192
01:26:43,840 --> 01:26:47,010
but it is still mechanical
energy transmitted

1193
01:26:47,010 --> 01:26:49,240
into the soft tissue so
we are still governed

1194
01:26:49,240 --> 01:26:52,120
by the ALARA principle,
which is the principle

1195
01:26:52,120 --> 01:26:54,180
that we have to use as, which is the,

1196
01:26:54,180 --> 01:26:55,900
As Low As Reasonably Achievable principle,

1197
01:26:55,900 --> 01:26:59,230
which means that we should
use as little invasiveness

1198
01:26:59,230 --> 01:27:01,160
into our patients as possible.

1199
01:27:01,160 --> 01:27:02,530
And so the energy that's emitted

1200
01:27:02,530 --> 01:27:04,440
by the probe can also be focused.

1201
01:27:04,440 --> 01:27:07,160
And in that case, just
like in a magnifying glass.

1202
01:27:07,160 --> 01:27:09,560
And so in that case, it could cause damage

1203
01:27:09,560 --> 01:27:12,960
and harm because you were
focusing mechanical energy

1204
01:27:12,960 --> 01:27:15,470
and it could cause cell disruption.

1205
01:27:15,470 --> 01:27:17,430
So it's very important
to remember that it's,

1206
01:27:17,430 --> 01:27:20,150
it's very safe, but in
the diagnostic range.

1207
01:27:20,150 --> 01:27:22,050
And so, and the biggest source of harm

1208
01:27:22,950 --> 01:27:25,380
in ultrasound is untrained users.

1209
01:27:25,380 --> 01:27:28,730
And so they, they can either hurt patients

1210
01:27:28,730 --> 01:27:32,150
by putting too much
energy into their bodies.

1211
01:27:32,150 --> 01:27:37,150
They can also misdiagnoses
and say that nothing's wrong

1212
01:27:37,800 --> 01:27:40,160
when in fact there's something is wrong

1213
01:27:40,160 --> 01:27:42,130
and they can also make the wrong diagnosis

1214
01:27:42,130 --> 01:27:44,420
saying something is wrong
but it's not the thing

1215
01:27:44,420 --> 01:27:45,450
that they said is wrong.

1216
01:27:45,450 --> 01:27:49,440
And so it's not just the, the
physical harm of ultrasound.

1217
01:27:49,440 --> 01:27:51,013
It's also the diagnostic harm.

1218
01:27:54,180 --> 01:27:59,180
So the, you know, the energy
that the ultrasonic imparts

1219
01:27:59,670 --> 01:28:04,600
onto patients soft tissues is measured

1220
01:28:04,600 --> 01:28:07,180
in the thermal index and
mechanical the index.

1221
01:28:07,180 --> 01:28:08,540
And these are, these are terms

1222
01:28:08,540 --> 01:28:11,100
that you don't have to
remember just important

1223
01:28:11,100 --> 01:28:13,477
to sort of discuss since
we're talking about it.

1224
01:28:13,477 --> 01:28:15,460
And the thermal index is
basically the absorption

1225
01:28:15,460 --> 01:28:19,650
of that mechanical energy by
the tissue converted into heat.

1226
01:28:19,650 --> 01:28:23,200
Whereas the mechanical
energy is that when,

1227
01:28:23,200 --> 01:28:25,440
when the sound beam causes refraction

1228
01:28:25,440 --> 01:28:29,360
or the pulling apart of
particles, it can do that in a,

1229
01:28:29,360 --> 01:28:33,780
in a way that can cause gas
bubbles within our bodies.

1230
01:28:33,780 --> 01:28:38,340
And so it can cause cavitation
or make holes inside organs

1231
01:28:38,340 --> 01:28:42,117
if the, if the sound beam
is high energy enough.

1232
01:28:42,117 --> 01:28:46,240
And so in the diagnostic
range, which is set by the FDA,

1233
01:28:46,240 --> 01:28:48,800
ultrasound is safe when used

1234
01:28:48,800 --> 01:28:52,060
by properly trained individuals.

1235
01:28:52,060 --> 01:28:55,210
And so the thermal index and
the mechanical index are,

1236
01:28:55,210 --> 01:28:58,043
are limited by the
ultrasound machine itself.

1237
01:28:59,640 --> 01:29:00,640
You have to remember though in,

1238
01:29:00,640 --> 01:29:04,753
in babies who smaller
than adults, or fetuses,

1239
01:29:05,600 --> 01:29:09,540
they're more sensitive to, to heat.

1240
01:29:09,540 --> 01:29:13,590
And so you don't wanna,
in first trimester,

1241
01:29:13,590 --> 01:29:17,783
overheat a fetus because
you could cause defects

1242
01:29:17,783 --> 01:29:20,420
in forming normal organs.

1243
01:29:20,420 --> 01:29:22,100
And so you have to be careful.

1244
01:29:22,100 --> 01:29:25,300
And so when we do imaging of the fetus,

1245
01:29:25,300 --> 01:29:27,460
we have to limit how much Doppler

1246
01:29:27,460 --> 01:29:31,550
and color ultrasound we are
doing, because these two things,

1247
01:29:31,550 --> 01:29:34,683
impart the most energy
in a diagnostic machine.

1248
01:29:40,660 --> 01:29:42,323
So we talked a little bit about,

1249
01:29:43,160 --> 01:29:44,400
we're gonna skip this particular video,

1250
01:29:44,400 --> 01:29:45,233
but we talked a little bit

1251
01:29:45,233 --> 01:29:48,900
about how ultrasound can
cause capitation and heating.

1252
01:29:48,900 --> 01:29:51,490
In fact, certain machines are designed

1253
01:29:51,490 --> 01:29:55,590
in such a way that they, they
are supposed to cause a lot

1254
01:29:55,590 --> 01:29:59,400
of heating and so that it
can heat up to a hundred

1255
01:29:59,400 --> 01:30:02,730
or 600 degrees Celsius
and cause coagulation.

1256
01:30:02,730 --> 01:30:06,020
And that can be used to
focus a beam of ultrasound

1257
01:30:06,020 --> 01:30:10,800
and treat things like
fibroids in the uterus and,

1258
01:30:10,800 --> 01:30:15,473
and sort of burn them without
having to cut them out.

1259
01:30:16,400 --> 01:30:19,210
And it can also treat prostate cancer.

1260
01:30:19,210 --> 01:30:22,240
And you can, some people
treat liver tumors

1261
01:30:23,080 --> 01:30:24,020
by heating them up

1262
01:30:24,020 --> 01:30:27,413
and basically cooking
them inside the body.

1263
01:30:28,270 --> 01:30:30,560
And you do it in such a
way that you focus the beam

1264
01:30:30,560 --> 01:30:32,440
that the tumor itself gets cooked,

1265
01:30:32,440 --> 01:30:35,903
but nothing around it is cooked and,

1266
01:30:37,040 --> 01:30:40,860
and no fava beans if you
guys know what that means.

1267
01:30:40,860 --> 01:30:43,610
So, oops, and then you can do
noninvasive plastic surgery,

1268
01:30:43,610 --> 01:30:47,090
which is basically they're
heating up the collagen

1269
01:30:47,090 --> 01:30:49,700
that's under the skin to
straighten it out as it,

1270
01:30:49,700 --> 01:30:52,620
as it sort of heats up, breaks up,

1271
01:30:52,620 --> 01:30:55,010
and as it cools off, it straightens out

1272
01:30:55,010 --> 01:30:56,410
and you get rid of wrinkles.

1273
01:30:58,960 --> 01:31:00,350
By the way I, if anybody's interested,

1274
01:31:00,350 --> 01:31:01,960
I do this on the side, on the weekends.

1275
01:31:01,960 --> 01:31:04,180
So give me a call.

1276
01:31:04,180 --> 01:31:05,410
No problem.

1277
01:31:05,410 --> 01:31:08,630
So contrast agents in ultrasound.

1278
01:31:08,630 --> 01:31:12,420
That's something that we talk
about a lot with CT and MRI,

1279
01:31:12,420 --> 01:31:14,310
but you can also have it with ultrasound

1280
01:31:14,310 --> 01:31:17,780
and it can characterize
lesions inside organs.

1281
01:31:17,780 --> 01:31:19,380
It can also characterize vessels

1282
01:31:20,380 --> 01:31:24,680
and you have the added benefit
of not having nephrotoxicity

1283
01:31:24,680 --> 01:31:28,293
like the contrast agents
used in CAT scan and MRI.

1284
01:31:29,450 --> 01:31:33,120
And the contrast agents are composed

1285
01:31:33,120 --> 01:31:37,680
of these little micro
bubbles inside of sort

1286
01:31:37,680 --> 01:31:40,960
of fat lobules and they
get injected intravenously,

1287
01:31:40,960 --> 01:31:42,800
they're tiny little micro bubbles

1288
01:31:42,800 --> 01:31:46,180
and while we're scanning
a particular lesion,

1289
01:31:46,180 --> 01:31:50,070
let's say in the liver, we watch the,

1290
01:31:50,070 --> 01:31:53,550
we watch the bubbles come,
come pouring into the lesion.

1291
01:31:53,550 --> 01:31:55,200
So here's a nice example of that.

1292
01:31:57,559 --> 01:32:00,120
Let's do a quick, so here's an ultrasound.

1293
01:32:00,120 --> 01:32:03,590
They found this mass here.

1294
01:32:03,590 --> 01:32:06,070
And they're gonna inject some contrast.

1295
01:32:06,070 --> 01:32:08,163
You're gonna watch it sort of light up.

1296
01:32:11,850 --> 01:32:14,080
Shortly, here we go.

1297
01:32:14,080 --> 01:32:16,860
So they start and inject
the ultrasound contrast,

1298
01:32:16,860 --> 01:32:20,220
no contrast yet you start to
see those gas bubbles coming in

1299
01:32:20,220 --> 01:32:21,540
through all the vessels.

1300
01:32:21,540 --> 01:32:25,523
And now the lesion is filling
up with the micro bubbles.

1301
01:32:26,870 --> 01:32:29,077
And so, you know, this is
what we call enhancement.

1302
01:32:29,077 --> 01:32:30,620
And we call it enhancement
in CAT scan, MRI,

1303
01:32:30,620 --> 01:32:35,080
and this is what enhancement
is on ultrasound.

1304
01:32:35,080 --> 01:32:40,080
Okay, so some descriptive terms
that we use in ultrasound.

1305
01:32:40,280 --> 01:32:42,200
We use the word echogenicity

1306
01:32:42,200 --> 01:32:45,760
which is the amount of echos
or interfaces inside something.

1307
01:32:45,760 --> 01:32:47,860
Something that's echogenic or hyperechoic

1308
01:32:47,860 --> 01:32:49,827
is brighter than adjacent tissues.

1309
01:32:49,827 --> 01:32:52,540
And remember everything here is relative.

1310
01:32:52,540 --> 01:32:54,540
Something that's isoechoic is the same

1311
01:32:54,540 --> 01:32:56,110
as the adjacent tissues.

1312
01:32:56,110 --> 01:32:58,620
Something that's hypoechoic has less echos

1313
01:32:58,620 --> 01:33:00,480
or is darker than adjacent tissues

1314
01:33:00,480 --> 01:33:02,300
and something that's anechoic at all,

1315
01:33:02,300 --> 01:33:04,620
or completely anechoic,
has no echoes at all

1316
01:33:04,620 --> 01:33:06,620
and is much darker than
the adjacent tissues.

1317
01:33:06,620 --> 01:33:09,140
So here's an example of
a hyperechoic lesion.

1318
01:33:09,140 --> 01:33:11,683
It's brighter than the
adjacent liver here.

1319
01:33:14,200 --> 01:33:16,427
Something that is isoechoic

1320
01:33:16,427 --> 01:33:19,520
and hypoechoic usually
has very little sort of

1321
01:33:20,420 --> 01:33:23,340
useful information for,
for diagnostic purposes

1322
01:33:25,260 --> 01:33:26,600
and then something that's oh,

1323
01:33:26,600 --> 01:33:29,920
so here's a mostly isoechoic
lesion, here is normal liver

1324
01:33:29,920 --> 01:33:33,440
and this lesion is pretty
similar to the liver nearby,

1325
01:33:33,440 --> 01:33:34,870
and it's a lot harder to see

1326
01:33:34,870 --> 01:33:36,100
when you don't have calipers on it.

1327
01:33:36,100 --> 01:33:38,373
So here is a liver lesion here.

1328
01:33:39,270 --> 01:33:42,240
Whereas it's very useful to
have an anechoic lesion here,

1329
01:33:42,240 --> 01:33:43,580
which is basically a simple cyst

1330
01:33:43,580 --> 01:33:47,670
and it can be, in short
just ignored all together.

1331
01:33:47,670 --> 01:33:50,693
And it's again, fluid filled
structure, always benign.

1332
01:33:52,870 --> 01:33:53,703
Hang on a second.

1333
01:33:53,703 --> 01:33:55,800
I'm getting a, just wanna
check the chat thing.

1334
01:33:58,040 --> 01:34:00,880
Oh, okay, so it's a
question about what type

1335
01:34:00,880 --> 01:34:04,440
of gas is being used and
concerns for embolism.

1336
01:34:04,440 --> 01:34:06,760
No, so it's not just a pure gas.

1337
01:34:06,760 --> 01:34:08,770
It's gas inside of micelles.

1338
01:34:08,770 --> 01:34:13,064
And so these, yeah, so it's,

1339
01:34:13,064 --> 01:34:15,450
it's these micro bubbles that are,

1340
01:34:15,450 --> 01:34:18,350
are inside of micelles
and so they're safe.

1341
01:34:18,350 --> 01:34:20,420
In fact, they're used as
what we call bubble studies

1342
01:34:20,420 --> 01:34:24,280
in cardiology to see
if they cross into the,

1343
01:34:24,280 --> 01:34:26,410
from right side of the heart
to left side of the heart

1344
01:34:26,410 --> 01:34:29,610
and that's expected and
they don't cause embola

1345
01:34:29,610 --> 01:34:30,890
into the brain or anywhere else

1346
01:34:30,890 --> 01:34:34,750
and they just get
absorbed into the tissues.

1347
01:34:34,750 --> 01:34:39,530
So they are, it is a safe thing to inject.

1348
01:34:39,530 --> 01:34:42,920
So not straight air, just to be sure.

1349
01:34:42,920 --> 01:34:46,350
It is a, it's a saline
solution with these micelles

1350
01:34:46,350 --> 01:34:47,810
of gas inside of them.

1351
01:34:47,810 --> 01:34:51,723
The gas is protected by the,
by the little lipid molecules.

1352
01:34:53,000 --> 01:34:55,340
So how do we use ultrasound?

1353
01:34:55,340 --> 01:34:57,990
The applications of
ultrasound are wide here

1354
01:35:00,471 --> 01:35:02,560
and there's lots more.

1355
01:35:02,560 --> 01:35:05,500
There's, I just wanna show you real quick

1356
01:35:05,500 --> 01:35:09,300
about what the different
types of ultrasound here.

1357
01:35:09,300 --> 01:35:13,100
And so, you know, so
here's the 2D ultrasound.

1358
01:35:13,100 --> 01:35:16,050
Just, this is what we think of
when we think of ultrasound.

1359
01:35:17,090 --> 01:35:18,540
Oop, let me go back and just.

1360
01:35:20,011 --> 01:35:21,340
This is what's called 3D ultrasound,

1361
01:35:21,340 --> 01:35:24,420
which is basically a probe
gets a large, you know,

1362
01:35:24,420 --> 01:35:26,941
large volume of data and reconstructs it

1363
01:35:26,941 --> 01:35:28,180
in three dimensions.

1364
01:35:28,180 --> 01:35:32,240
You have to have, it's
mostly done for fetal imaging

1365
01:35:32,240 --> 01:35:35,870
because the fetus is surrounded by fluid

1366
01:35:35,870 --> 01:35:38,570
so they're able to sort of do
this kind of post-processing.

1367
01:35:38,570 --> 01:35:41,230
And then the 4D ultrasound
is when you can,

1368
01:35:41,230 --> 01:35:45,750
can watch a baby moving around
live in there in the uterus.

1369
01:35:45,750 --> 01:35:47,880
So that's kind of the,
some of the terminology

1370
01:35:47,880 --> 01:35:48,993
from that perspective.

1371
01:35:51,290 --> 01:35:53,680
Okay, and just remember, you know,

1372
01:35:53,680 --> 01:35:56,670
for those of you who
end up having children,

1373
01:35:56,670 --> 01:35:58,590
that the more scans you end up doing,

1374
01:35:58,590 --> 01:36:02,660
the more heat you're
imparting onto your fetus.

1375
01:36:02,660 --> 01:36:05,130
So don't do it willy-nilly,

1376
01:36:05,130 --> 01:36:06,460
especially in the first trimester.

1377
01:36:06,460 --> 01:36:07,837
Later on when they're just
about ready to come out,

1378
01:36:07,837 --> 01:36:09,880
you just wanna see them that's, it's okay.

1379
01:36:09,880 --> 01:36:11,380
There's not that much heating.

1380
01:36:13,180 --> 01:36:15,960
So let me just make sure I
answer all the chat questions

1381
01:36:15,960 --> 01:36:17,903
before I go on to MRI.

1382
01:36:20,940 --> 01:36:22,470
Okay, good.

1383
01:36:22,470 --> 01:36:26,990
All right, so MRI and this,

1384
01:36:26,990 --> 01:36:28,410
a lot of this information was taken

1385
01:36:28,410 --> 01:36:30,950
from a colleague of mine,

1386
01:36:30,950 --> 01:36:32,963
was a physicist much smarter than I am.

1387
01:36:34,310 --> 01:36:38,020
So definition of nuclear
magnetic resonance.

1388
01:36:38,020 --> 01:36:41,233
Nuclear, its property uses
nucleus to give us the signal.

1389
01:36:42,120 --> 01:36:45,040
And so in MRI for diagnostic purposes,

1390
01:36:45,040 --> 01:36:48,470
that nucleus is hydrogen,
which is just a single proton.

1391
01:36:48,470 --> 01:36:51,810
That's basically what we're
imaging is the hydrogen proton

1392
01:36:51,810 --> 01:36:53,110
in everybody's bodies.

1393
01:36:53,110 --> 01:36:56,620
And so the magnetic
properties of the nucleus

1394
01:36:56,620 --> 01:36:58,950
is what we manipulate with
nuclear magnetic resonance

1395
01:36:58,950 --> 01:37:01,033
and MRI imaging.

1396
01:37:02,220 --> 01:37:05,693
And the hydrogen is one of the few nuclei

1397
01:37:07,210 --> 01:37:10,100
that has a magnetic moment
so we're able to image it.

1398
01:37:10,100 --> 01:37:13,520
And thankfully, most of us are
made of predominantly water.

1399
01:37:13,520 --> 01:37:17,440
And so lots of hydrogen molecules in us.

1400
01:37:17,440 --> 01:37:20,830
And then resonance is
object that resinates

1401
01:37:20,830 --> 01:37:23,990
when they're exposed to forces
at their natural frequency.

1402
01:37:23,990 --> 01:37:26,960
And so a example of
something like that is,

1403
01:37:26,960 --> 01:37:29,150
is a guitar string or when the singers

1404
01:37:29,150 --> 01:37:30,910
are breaking wineglasses with their voice

1405
01:37:30,910 --> 01:37:35,230
because the match, match
the resonance frequency

1406
01:37:35,230 --> 01:37:37,980
of the glass material.

1407
01:37:37,980 --> 01:37:40,520
And then same thing with the,
with the bridges and the wind

1408
01:37:40,520 --> 01:37:43,950
is that the, the frequency
of the wind gusting

1409
01:37:43,950 --> 01:37:46,333
matches the frequency of the bridge.

1410
01:37:48,750 --> 01:37:53,570
So this was a cave drawing found
several thousand years ago,

1411
01:37:53,570 --> 01:37:58,330
predicting the MRI is
going to founded in 1947

1412
01:37:58,330 --> 01:38:00,743
by Dr. Bloch and Purcell.

1413
01:38:02,591 --> 01:38:04,660
And the first clinical
magnetic resonance imaging

1414
01:38:04,660 --> 01:38:07,860
was obtained in 1977.

1415
01:38:07,860 --> 01:38:12,150
So I spent some time figuring
out how to squeeze all

1416
01:38:12,150 --> 01:38:16,760
of MRI physics into one
page and this is what it is.

1417
01:38:16,760 --> 01:38:19,960
So you guys can, only parts
of this will be tested.

1418
01:38:19,960 --> 01:38:23,160
Sort of the, the left mid
and the left lower part

1419
01:38:23,160 --> 01:38:25,853
you have to memorize and
the rest don't worry about.

1420
01:38:27,360 --> 01:38:31,750
So where does the MR image come from?

1421
01:38:31,750 --> 01:38:35,320
And so it's this thing,
that's where it comes from,

1422
01:38:35,320 --> 01:38:38,260
and it comes from there and
we read it and we're done

1423
01:38:38,260 --> 01:38:43,260
and we just move on with our
day, but how does it do it?

1424
01:38:43,820 --> 01:38:48,820
And so, again, we're
made of fluid about 70%.

1425
01:38:48,900 --> 01:38:52,610
And, and we, the only thing
that for the most part,

1426
01:38:52,610 --> 01:38:56,040
the only thing that the
MRI machine sees is the,

1427
01:38:56,040 --> 01:38:58,513
is the protons that, that's in the water.

1428
01:39:00,170 --> 01:39:01,860
And again, these protons
have a magnetic moment

1429
01:39:01,860 --> 01:39:03,390
which has a vector.

1430
01:39:03,390 --> 01:39:07,680
And so it's, and these protons
are always spinning like this

1431
01:39:07,680 --> 01:39:09,710
and wobbling, so it's not a straight spin.

1432
01:39:09,710 --> 01:39:11,460
It's always wobbling back and forth

1433
01:39:11,460 --> 01:39:13,990
and we call that wobble the pre-session.

1434
01:39:13,990 --> 01:39:15,160
Just like a spinning top here.

1435
01:39:15,160 --> 01:39:18,070
So again this nucleus or this proton,

1436
01:39:18,070 --> 01:39:20,520
it's constantly spinning
and constantly wobbling.

1437
01:39:23,110 --> 01:39:27,900
So inside the tube, most
of the protons in our body,

1438
01:39:27,900 --> 01:39:31,160
once we're in the tube, get
aligned in the same direction

1439
01:39:31,160 --> 01:39:32,670
by this B0 coil.

1440
01:39:32,670 --> 01:39:35,530
So there's a coil that
exerts a magnetic field

1441
01:39:35,530 --> 01:39:36,530
and that's what we talk about

1442
01:39:36,530 --> 01:39:39,710
when we say three Tesla
magnet, or 1.5 Tesla magnet,

1443
01:39:39,710 --> 01:39:42,230
it's that B0 field that we're discussing.

1444
01:39:42,230 --> 01:39:45,140
And that's the strength
of the field inside that,

1445
01:39:45,140 --> 01:39:46,290
inside the tube here.

1446
01:39:46,290 --> 01:39:48,597
And so the stronger the field,

1447
01:39:48,597 --> 01:39:51,480
the more molecules align along the

1448
01:39:51,480 --> 01:39:53,930
whatever vector you want them to align.

1449
01:39:53,930 --> 01:39:56,080
So that's B0 field,
that's what this B0 is.

1450
01:39:59,120 --> 01:40:02,220
And then we use something
called these gradient coils.

1451
01:40:02,220 --> 01:40:05,220
And what these gradient
coils do is they apply

1452
01:40:06,730 --> 01:40:09,210
slightly different fields
in different directions

1453
01:40:09,210 --> 01:40:12,560
inside of, of the tube,
inside of the bore.

1454
01:40:12,560 --> 01:40:16,140
And that based on the
alignment of the protons

1455
01:40:16,140 --> 01:40:20,220
along the way of the bore,
we know exactly where,

1456
01:40:20,220 --> 01:40:22,870
where a proton is because
we know exactly where,

1457
01:40:22,870 --> 01:40:26,270
how it should be sort of spinning
or wobbling or precessing.

1458
01:40:26,270 --> 01:40:29,960
And so here, the protons are
wobbling in a difference,

1459
01:40:29,960 --> 01:40:31,397
in a different way than
they are wobbling here

1460
01:40:31,397 --> 01:40:33,080
and here and here.

1461
01:40:33,080 --> 01:40:36,510
And so in fact, not only that
within this single slice,

1462
01:40:36,510 --> 01:40:39,880
in every little dot in
that slice there the,

1463
01:40:39,880 --> 01:40:42,130
the protons are wobbling
in slightly different way

1464
01:40:42,130 --> 01:40:43,843
because of these gradient coils.

1465
01:40:46,060 --> 01:40:51,060
And so, additionally the,
after these gradient coils

1466
01:40:51,360 --> 01:40:54,380
sort of encode location in our body,

1467
01:40:54,380 --> 01:40:57,550
we send out a radio-frequency pulse,

1468
01:40:57,550 --> 01:40:59,120
which transfers a little bit of energy

1469
01:40:59,120 --> 01:41:01,570
into a specific area in the field.

1470
01:41:01,570 --> 01:41:04,450
So we tell it where to go, which slice,

1471
01:41:04,450 --> 01:41:09,080
and based on that, it excites
those protons a little bit.

1472
01:41:09,080 --> 01:41:13,000
And, and as it, as those protons relax,

1473
01:41:13,000 --> 01:41:13,940
it creates our image.

1474
01:41:13,940 --> 01:41:15,950
And I'll, I'll try to
get into it a little bit.

1475
01:41:15,950 --> 01:41:17,070
Don't worry about getting too far

1476
01:41:17,070 --> 01:41:18,970
into the weeds of the physics of this.

1477
01:41:21,010 --> 01:41:24,670
Hopefully it will be okay.

1478
01:41:24,670 --> 01:41:26,699
So looks like he has a,
have a lecture at 4:00.

1479
01:41:26,699 --> 01:41:28,449
I'll try to go a little bit faster.

1480
01:41:29,740 --> 01:41:34,330
So I'll go to the important slide.

1481
01:41:34,330 --> 01:41:35,490
So this is a receive coil.

1482
01:41:35,490 --> 01:41:37,950
So once, once your protons go back

1483
01:41:37,950 --> 01:41:42,950
to their normal form they,
they emit some more energy

1484
01:41:44,840 --> 01:41:47,190
and the receive coils receive
that and make an image.

1485
01:41:47,190 --> 01:41:49,420
By the way, if you guys
need to go, go ahead and go.

1486
01:41:49,420 --> 01:41:50,360
These are gonna be recorded

1487
01:41:50,360 --> 01:41:52,560
and you can watch the
rest of it at the end.

1488
01:41:54,010 --> 01:41:59,010
So again, after the, the RF
beam is sent into the body,

1489
01:42:00,570 --> 01:42:03,720
the protons reflects back
to their original state

1490
01:42:03,720 --> 01:42:04,940
and release the energy back

1491
01:42:04,940 --> 01:42:06,590
and that's how we get our image in.

1492
01:42:06,590 --> 01:42:09,190
And then the four-way transfer happens,

1493
01:42:09,190 --> 01:42:10,950
which is a magical thing.

1494
01:42:10,950 --> 01:42:14,623
And that creates our image
that looks like this.

1495
01:42:16,820 --> 01:42:18,980
So I'm not gonna, this
is not gonna be tested.

1496
01:42:18,980 --> 01:42:20,220
So I'm not gonna go through it.

1497
01:42:20,220 --> 01:42:25,220
If you guys want to read
through it, you can,

1498
01:42:27,820 --> 01:42:29,240
but we'll just move on.

1499
01:42:29,240 --> 01:42:31,078
And so we'll talk about MRI safety

1500
01:42:31,078 --> 01:42:32,378
because that is important.

1501
01:42:33,225 --> 01:42:35,560
A three Tesla magnet is
what we use clinically

1502
01:42:35,560 --> 01:42:36,890
to image our patients,

1503
01:42:36,890 --> 01:42:39,963
but it can also is strong
enough to pick up a little car.

1504
01:42:40,920 --> 01:42:44,860
Unfortunately, MRI can also be dangerous

1505
01:42:44,860 --> 01:42:49,860
and if the wrong things are
pushed into the MR room,

1506
01:42:50,530 --> 01:42:52,520
they get pulled in to the MR magnet,

1507
01:42:52,520 --> 01:42:55,240
and unfortunately they can kill people,

1508
01:42:55,240 --> 01:42:57,673
especially if one of these
gets thrown in there.

1509
01:42:59,360 --> 01:43:01,750
So anything that's
ferromagnetic can be acted on

1510
01:43:01,750 --> 01:43:03,320
by the magnet and get pulled in.

1511
01:43:03,320 --> 01:43:06,450
That's why we have to all
change into a proper attire

1512
01:43:06,450 --> 01:43:09,610
before we go into the MR room.

1513
01:43:09,610 --> 01:43:11,300
Patients go through a
detailed questionnaire

1514
01:43:11,300 --> 01:43:13,300
about prior metallic
fragments in their body

1515
01:43:13,300 --> 01:43:16,707
and their eyes and
documentation of medical devices

1516
01:43:16,707 --> 01:43:18,200
in the body is very important.

1517
01:43:18,200 --> 01:43:21,683
Some are MRI safe and some
are not, some implants.

1518
01:43:22,920 --> 01:43:25,780
So here's an example where
this BB in somebody's eye

1519
01:43:25,780 --> 01:43:28,130
is very important because
this could make them go blind

1520
01:43:28,130 --> 01:43:30,663
if they're go into the
magnet and this moves,

1521
01:43:31,790 --> 01:43:35,230
if they aren't blind
already, that is from the BB.

1522
01:43:35,230 --> 01:43:37,630
And this for example is
a little shard of metal

1523
01:43:37,630 --> 01:43:39,890
in somebody's calf, not
gonna cause any problems.

1524
01:43:39,890 --> 01:43:41,370
The worst that could
happen is it might get

1525
01:43:41,370 --> 01:43:43,640
a little bit warm inside the magnet.

1526
01:43:43,640 --> 01:43:46,353
But this is the one that we
wanna make sure we don't miss.

1527
01:43:47,510 --> 01:43:51,900
And this is a famous actor
who was here earlier,

1528
01:43:51,900 --> 01:43:53,980
and this was not MRI safe

1529
01:43:53,980 --> 01:43:55,703
so we couldn't put him in a magnet.

1530
01:43:57,110 --> 01:43:59,550
Oop, sorry, we're not
gonna go through this.

1531
01:43:59,550 --> 01:44:02,333
This is a, you guys can
Google Quench very loud.

1532
01:44:04,080 --> 01:44:07,530
More MRI safety, so the
RF pulses that we sent

1533
01:44:07,530 --> 01:44:09,400
into the body impart
a little bit of energy

1534
01:44:09,400 --> 01:44:11,300
in the soft tissues and cause heating.

1535
01:44:12,280 --> 01:44:14,520
Again, this is clinically
most important in fetuses,

1536
01:44:14,520 --> 01:44:16,020
especially in first trimester,

1537
01:44:17,510 --> 01:44:21,220
who should not get heated up.

1538
01:44:21,220 --> 01:44:22,193
Sedated patients who can't tell us

1539
01:44:22,193 --> 01:44:23,550
that they're getting heated up

1540
01:44:23,550 --> 01:44:27,690
or they're getting burnt
can also be a problem.

1541
01:44:27,690 --> 01:44:30,040
And any patient that has issues

1542
01:44:30,040 --> 01:44:32,183
with regulating their temperatures.

1543
01:44:33,270 --> 01:44:36,020
Magnetic fields that are
higher than three Tesla

1544
01:44:36,020 --> 01:44:39,830
can cause actual nerve stimulation

1545
01:44:39,830 --> 01:44:42,750
and alter enzymes function in our bodies,

1546
01:44:42,750 --> 01:44:44,783
but they're not used clinically.

1547
01:44:46,160 --> 01:44:48,260
It's very loud in there,
if any of you been in MR.

1548
01:44:48,260 --> 01:44:51,720
So we have to make sure
we use ear protection

1549
01:44:51,720 --> 01:44:52,840
for our patients.

1550
01:44:52,840 --> 01:44:55,120
The gadolinium contrast that we use to,

1551
01:44:55,120 --> 01:44:58,660
for our MRI, can rarely
cause something called

1552
01:44:58,660 --> 01:45:02,100
nephrogenic systemic fibrosis
and/or organ deposition.

1553
01:45:02,100 --> 01:45:04,650
This is making a lot of
headlines now in the brain.

1554
01:45:06,360 --> 01:45:10,030
This more, this happens in
renally impaired patients,

1555
01:45:10,030 --> 01:45:13,630
the NSF, the organ
deposition is felt through,

1556
01:45:13,630 --> 01:45:16,800
nobody understands exactly who gets more

1557
01:45:16,800 --> 01:45:19,870
of the brain deposition than, than others.

1558
01:45:19,870 --> 01:45:22,380
That's still being investigated.

1559
01:45:22,380 --> 01:45:25,383
And, and all these things
are regulated by the FDA.

1560
01:45:27,230 --> 01:45:29,290
So what's MRI good for?

1561
01:45:29,290 --> 01:45:30,390
For soft tissue resolution.

1562
01:45:30,390 --> 01:45:33,410
Here's a, here's a brain
of a, of a young child.

1563
01:45:33,410 --> 01:45:35,987
You can see the CAT scan,
you can kind of see things.

1564
01:45:35,987 --> 01:45:37,521
You can kind of see the difference

1565
01:45:37,521 --> 01:45:38,500
between the different soft tissues.

1566
01:45:38,500 --> 01:45:40,870
Whereas here, the difference is superb.

1567
01:45:40,870 --> 01:45:42,630
You can see the (stammering)

1568
01:45:42,630 --> 01:45:44,930
the gray matter and the
white matter difference.

1569
01:45:44,930 --> 01:45:47,300
You can see where the
ventricles start and stop.

1570
01:45:47,300 --> 01:45:48,300
You can see the vessels.

1571
01:45:48,300 --> 01:45:50,520
It's, it's amazing.

1572
01:45:50,520 --> 01:45:53,790
In the abdomen, everything's
a little bit washed out.

1573
01:45:53,790 --> 01:45:55,870
Whereas here you can see
the cortical measure,

1574
01:45:55,870 --> 01:45:58,120
the differentiation of
the kidney, much better.

1575
01:45:58,120 --> 01:45:59,380
The spleen and the liver,

1576
01:45:59,380 --> 01:46:02,893
all the internal structures of
these organs is much better.

1577
01:46:04,680 --> 01:46:05,600
And of course, in the shoulder,

1578
01:46:05,600 --> 01:46:08,410
they're comparing x-ray
to CAT scan to MRI.

1579
01:46:08,410 --> 01:46:11,760
You can see even the little
slips inside the muscles,

1580
01:46:11,760 --> 01:46:14,660
much better than you can in anything else.

1581
01:46:14,660 --> 01:46:17,574
So soft tissue resolution, very important.

1582
01:46:17,574 --> 01:46:18,770
It's not very good for air.

1583
01:46:18,770 --> 01:46:19,930
So here are the lungs.

1584
01:46:19,930 --> 01:46:23,290
You can see the lungs on
CAT scan here on the bottom.

1585
01:46:23,290 --> 01:46:24,970
You can see some of the
architecture of the lungs,

1586
01:46:24,970 --> 01:46:26,940
whereas on the MR, you see nothing.

1587
01:46:26,940 --> 01:46:28,400
It's just a black void.

1588
01:46:28,400 --> 01:46:30,170
Same thing with cortical bone.

1589
01:46:30,170 --> 01:46:32,010
You can't, there's not
many protons in there.

1590
01:46:32,010 --> 01:46:33,073
It's just black.

1591
01:46:33,930 --> 01:46:36,600
And unfortunately,
metallic artifacts here.

1592
01:46:36,600 --> 01:46:40,100
There's a metallic shunt
here that causes artifact.

1593
01:46:40,100 --> 01:46:42,760
This patient's brain is not blowing up.

1594
01:46:42,760 --> 01:46:46,373
It's just the artifact from
the metallic implanted device.

1595
01:46:49,840 --> 01:46:52,250
Some of the terms we use in MRI.

1596
01:46:52,250 --> 01:46:54,620
Intensity, which is the relative,

1597
01:46:54,620 --> 01:46:57,020
as opposed to echogenicity
that we use in ultrasound.

1598
01:46:57,020 --> 01:46:59,250
It's the relative
brightness on the screen.

1599
01:46:59,250 --> 01:47:00,750
It's spit out by the four-way transfer

1600
01:47:00,750 --> 01:47:03,110
which is that magical formula.

1601
01:47:03,110 --> 01:47:05,230
Something is relatively hyperintense,

1602
01:47:05,230 --> 01:47:07,130
it is brighter than another
tissue in comparison.

1603
01:47:07,130 --> 01:47:09,790
So here is hyperintense
compared to the kidney

1604
01:47:09,790 --> 01:47:11,520
or hyperintense compared to the liver.

1605
01:47:11,520 --> 01:47:14,410
So fat is hyperintense
to liver on this image.

1606
01:47:14,410 --> 01:47:16,900
Or isointense, which is
the same as another tissue

1607
01:47:16,900 --> 01:47:19,170
in comparison or
hypointense which is darker.

1608
01:47:19,170 --> 01:47:22,530
So here's lung again, which
is hypointense to the liver

1609
01:47:22,530 --> 01:47:23,830
and the spleen next to it.

1610
01:47:26,132 --> 01:47:27,820
And it's all, again,
and it's all relative.

1611
01:47:27,820 --> 01:47:29,190
In each sequence you might,

1612
01:47:29,190 --> 01:47:32,513
you might get out of an MRI
scanner might look different.

1613
01:47:35,630 --> 01:47:38,970
So applications of MRI are various and,

1614
01:47:38,970 --> 01:47:42,130
and all new uses are
always being discovered.

1615
01:47:42,130 --> 01:47:45,850
And for example, more recently evaluating

1616
01:47:45,850 --> 01:47:48,350
for fibrosis in the
liver using non-invasive

1617
01:47:48,350 --> 01:47:51,440
without having to biopsy
the liver to figure out

1618
01:47:51,440 --> 01:47:54,100
if the patient has a
fibrosis and cirrhosis.

1619
01:47:54,100 --> 01:47:56,880
Also looking at liver
iron deposition with MRI,

1620
01:47:56,880 --> 01:47:57,923
as opposed to having to biopsy the liver

1621
01:47:57,923 --> 01:47:59,423
to be able to see that.

1622
01:48:01,940 --> 01:48:03,200
And that's it.

1623
01:48:03,200 --> 01:48:04,950
I apologize I went over.

1624
01:48:04,950 --> 01:48:06,070
Again, these are all recorded.

1625
01:48:06,070 --> 01:48:09,260
You can go back and read,
and look at them again

1626
01:48:09,260 --> 01:48:10,820
and go through them again.

1627
01:48:10,820 --> 01:48:12,810
Feel free to reach out to
us if you have any questions

1628
01:48:12,810 --> 01:48:14,731
on particular lectures,

1629
01:48:14,731 --> 01:48:16,933
or if you have any
questions about anything.

1630
01:48:18,900 --> 01:48:20,150
About the course that is.

1631
01:48:21,053 --> 01:48:23,343
Anybody have any questions at the moment?

1632
01:48:27,090 --> 01:48:29,330
Great, thank you all so much for joining

1633
01:48:29,330 --> 01:48:31,030
and have a great rest of your day.

1634
01:48:35,030 --> 01:48:36,030
- [Woman] Thank you.