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Here we have a teenager with foot pain.

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Uh, we did plain films, uh, she revealed

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nothing, and now we are getting MRIs to see if

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there's, if we can find anything on the MRI.

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And I'm showing you this case to

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demonstrate that you can have patchy

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bone marrow signal and still be normal.

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And giving you just a little idea of what

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normal bone marrow signal looks like, uh, and

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not how to confuse it with abnormal signal.

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So let's just go through this.

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Uh, some of the images, and I think it's

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most constructive to look at it on a

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fat-suppressed, fluid-sensitive sequence.

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As you notice, first of all, the metaphysis

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here has the trilaminar appearance.

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We've got the true physis

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here, which is cartilage.

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The dark area is the zone of provisional

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calcification, and the brighter

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area above that, which is part of

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the metaphysis, is the spongiosa.

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This is where the blood vessels are very

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rich, and a lot of humeral factors come in.

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Okay.

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In addition to that, you notice the metaphysis

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has sort of a blush type of appearance.

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It's like somebody's taken

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a paintbrush and swiped up.

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There's no clear demarcation of where

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the bright area ends and the darker

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area of the fatty marrow begins.

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So that's a very typical appearance

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of a pediatric metaphysis.

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If you can take a pencil and draw a line

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between the border of the dark area and

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the bright area, then that is abnormal.

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You don't want to be able

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to do that in the marrow.

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You want the slight brushed type of appearance.

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A similar concept can be applied to what we

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see in the tarsal bones, including talus and

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the calcaneus and the various cuneiforms.

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As I look through this, I see these

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patchy areas of bright signal.

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You see one over here.

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It almost looks like central edema

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with spider-like protuberances

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or extensions from the center.

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Again, nothing I can take a pencil and draw

1:58

around with a clear demarcation separating

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the very dark areas from the brighter areas.

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That is normal residual hematopoietic

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marrow or responses to normal

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stress in the pediatric population.

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There's a little debate about what that is

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exactly, but in general, that seems to be one

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of the two things that people think it is.

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And it can be a combination of both.

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You see another sort of blush type over here,

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another blush high signal over here, and it can

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be a little bit more well-defined, like here.

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But again, it's not like I can take a

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pencil and really make a nice cutout.

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Typically, they're located within

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sort of the body of the marrow.

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Typically, they don't occur just under

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the cartilage or just

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under the cortical surface.

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If you start to see that, then you begin to

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worry maybe this is not just simple marrow.

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Maybe it's an osteochondral

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lesion that's presenting itself.

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And as the more you look, the more you'll find.

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Again, you see some here in the tarsal bones.

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As we go further, we see more

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high signal here and here.

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So that's very, very typical.

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It's not just the foot.

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You'll see it in the carpal bones a lot too.

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And even sometimes in the distal long

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extremities like the tibia and fibula.

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So, please don't confuse that

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with abnormal bone marrow.