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Dr. P. talking renal masses here.

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3 00:00:01,560 --> 00:00:03,150

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I've got before you on the left an

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out of phase GRE with a short TE.

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Look at the India ink effect, this

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dark line between the kidney and the

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surrounding fat, a fat-water interface.

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An in-phase GRE with a slightly

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longer TE, and then a T2 fast spin echo without supression.

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This is a 65-year-old lady who two years ago

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had a renal mass in the left posterior kidney.

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She has multiple renal masses, many of

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which are cysts, some hemorrhagic cysts.

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And then, two years later, while this lesion

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is being followed, it goes from one to two

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centimeters, namely this one in the back.

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So when we look at the in-phase GRE, the lesion is

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slightly hyperintense to the rest of the kidney.

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Not as much as this lesion is.

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But when we go out of phase, that lesion does not

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drop out, hemorrhagic cyst; this lesion does drop

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out, and suggests the presence of microscopic fat.

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Now where do we see microscopic fat in the kidney?

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We see microscopic fat in AML or angiomyolipoma,

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some renal cell carcinomas, and even in Wilms tumors.

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Let's talk briefly about AMLs, because AML,

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angiomyolipoma, not acute myelogenous leukemia.

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AML is the introductory topic for this vignette.

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Now on the right-hand side of

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your screen is a T2 spin echo.

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Many of the cysts are nice and

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bright and round and homogeneous.

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This lesion in the back of

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the left kidney, not so much.

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So we have a problem.

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So a couple of questions to be answered.

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First, what is it?

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Second, is it aggressive or non-aggressive?

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And how are we gonna, how are we gonna do that on MRI?

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Uh, there are a few tools we have in our toolbox.

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We've got diffusion-weighted MR, although that is

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not incredibly reliable in making that distinction.

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If it heavily diffusion restricts, that might push

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us one way, but it's not pathognomonic of malignancy.

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And we've got hypervascularity.

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Hypervascularity could occur, and does

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occur, in angiomyolipomas, but it also

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occurs in many renal cell carcinomas.

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Let's touch on angiomyolipoma for a minute.

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As a mass, I'm going to bring down the

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diffusion image and show you that the,

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the lesion is weakly diffusion restricted.

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Angiomyolipoma occurs most frequently

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in the fourth through sixth decades of life with

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increased prevalence in women.

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This is a woman.

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She is 65 years of age, so pretty close

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to the peak age group.

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These are now regarded as part of the

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family of perivascular epithelioid or

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epithelioid cell tumors, also known as PEComas.

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And it comprises a heterogeneous group of tumors with

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variable pathologic imaging and clinical features.

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AML is typically composed of variable

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amounts of dysmorphic blood vessels, which

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is why it's hypervascular, smooth muscle

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components, and mature adipose tissue.

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But not all of them have macroscopic fat.

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Some have microscopic fat, and most of

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these are sporadic, 80% of the time.

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But, the remaining 20% are associated with

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tuberous sclerosis complex, and may be associated

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with lymphangioleiomyomatosis, and here we've got an

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indeterminate lesion that requires further definition.

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Now, one of the first things I might do here is

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give contrast and look at the arterial phase, the

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portal venous phase, and the nephrogenic phase.

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So I'll look at 30 to 60 seconds,

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60 to 90 seconds and so on.

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But let's go early.

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Let's go around 45 or 50 seconds, maybe

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a little longer than I would have liked.

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But we do have a nice crisp

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arterial enhancement pattern.

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And our lesion is lighting up

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and lighting up pretty briskly.

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So that doesn't tell us between the two which it is.

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But it does tell us that it is not a hemorrhagic cyst.

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You can see our hemorrhagic cyst

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did not invert or suppress when we went out of phase,

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like a micro or macroscopic

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fat-containing lesion might do.

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Our hemorrhagic cyst stayed nice and bright.

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Our hemorrhagic cyst is cold.

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It has no contrast enhancement.

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Our lesion, it's hot.

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It's hypervascular.

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If we go all the way down the road to something

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a lot later, and say the, uh, the delayed phase,

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two, three, four minutes, our mass is still

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hypervascular, although it's washing out a little bit.

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But clearly, vascular mass, complex

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character, has some fat in it.

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Now we've got a job to do.

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Is it AML or renal cell carcinoma?

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I suggest you move on to the next vignette.

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Dr. P out.