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Proximal to Distal Anatomy

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Let's focus on prostate anatomy

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from proximal to distal.

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This is, these are terms that are used to

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describe the base of the prostate,

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which is going to be up higher, and the apex of

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the prostate, which is going to be down lower.

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We're going to divide from top to

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bottom the prostate into, into thirds.

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So we got, we have an upper third,

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which is going to be the base.

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We're going to have a middle third,

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which is going to be the mid.

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Okay.

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And we're going to have a distal third,

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which is going to be the apical portion of the gland.

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You'll also hear the gland

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divided up from medial to lateral.

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Now, we've already given you some designations

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for the zones and some abbreviations for such.

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But, uh, some people will actually divide the

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gland into a more mesial intermediate portion of

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the gland and a less mesial intermediate portion.

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Lateral portion of the gland.

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And it's actually described as

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intermediate mesial and lateral lateral.

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So you'll hear that designation floating around.

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I personally will just call it, uh, medial

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versus lateral, which is pretty simple.

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And I will use the abbreviations that you

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learned in the Axial Anatomic Vignette.

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Okay, so let's take this all

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off the screen for a minute.

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And now let's look at the video.

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The gland appearance as we go from base to apex.

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Now this might be a little bit confusing, but it's

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actually not as challenging as you might think.

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So let's start with our axial pancake of

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a prostate gland here in the upper third.

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So in the front of the gland, we've got the left

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and right AS, or anterior fibromuscular stroma.

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Then we've got the transitional zone behind that.

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Let's make the transitional

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zone a little more posterior.

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And we're going to have a

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TZA and a TZP on each side.

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So you can divide that in half.

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And you're going to have the

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urethra and the periurethral tissue.

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We'll make that, uh, gray.

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Kind of smack dab in the middle there.

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And we'll even draw in the

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periurethral tissue just for giggles.

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Here's some periurethral tissue.

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Right here.

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And then behind that, we're going to

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have in blue, the, the central zone.

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And it kind of, kind of

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looks a little bit lobular.

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And the central zone and TZ

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make up the central gland.

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And they will progressively enlarge

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as you get a little bit older.

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And then everything else around

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the outside is going to be the PZ.

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So we're going to have right PZA, PZP,

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PZM in the back, and left the same thing.

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So that's your, that's your base appearance.

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Now let's go to the mid level of the

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gland, and I'm going to draw that again,

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but I'm going to keep my other diagram up

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intentionally so you can make a comparison.

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And now it's, it's virtually identical,

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except that the, the anterior fibromuscular

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stroma tends to coalesce more as sort of one.

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As you go down a little bit, they kind

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of bleed into each other, so you can't

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really distinguish so easily a separation.

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Between right and left.

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Now, the TZ, which we've got in, in orange, is

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going to kind of take over here at this level.

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We don't have a CZ, because the CZ is only

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up in the upper part of the gland,

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the central zone, part of the central gland.

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And then everything else is peripheral zone.

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We're going to have PZA, PZP,

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and PZM on the right and left.

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Alright, now we've got to go to

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the apical portion of the gland.

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Get our green color out again.

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The gland's getting smaller

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because you're going down.

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That's no secret or surprise.

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And now the transitional zone is also

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going to be a little bit smaller.

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But you're still going to have a

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smaller TZA and TZP, which are front

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and back bisected right in the middle.

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You're still going to have a

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urethra with periurethral tissue.

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I didn't bother to put it over here.

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I probably should have.

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Here's your urethra again.

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We've got some periurethral tissue around it.

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And you'll be able to separate those

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out by their signal intensity on MRI.

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And then everything else

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down low is going to be PZ.

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So there's no central zone down here.

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And the anterior fibromuscular stroma.

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Is once again going to bleed together

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in a kind of a short stubby little

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flat structure here anteriorly.

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Then we go down one more cut down at this level.

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We're out of the prostate gland

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and we're simply and purely in the urethra

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with the periurethral tissues around it.

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And then we run into the external

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sphincter in your genital diaphragm.

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And we have a sphincter up higher.

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At the level of the bladder.

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So those are the three basic

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levels you're going to see.

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Base, mid, and apex.

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And then you'll have a medial and a lateral or an

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intermediate and a lateral component to the gland.

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So let's move on to the sagittal

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if you have time to watch with us.

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Shall we?

Report

Editorial Note

Faculty

Stephen J Pomeranz, MD

Chief Medical Officer, ProScan Imaging. Founder, MRI Online

ProScan Imaging

John F. Feller, MD

Chief Medical Officer, HALO Diagnostics. Medical Director & Founder, Desert Medical Imaging. Chief of Radiology, American Medical Center, Shanghai, China.

HALO Diagnostics

Tags

Prostate/seminal vesicles

MRI

Iatrogenic

Genitourinary (GU)

Body

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