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Here is an interesting case that typically

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affects a teenage woman with some psychiatric issues sometimes,

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and sometimes issues with how they perceived their own bodies.

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And this is a great case of anorexia nervosa.

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For this case,

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I've actually given you the parameters on the left-hand side.

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If you look at this,

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this is labeled as a sagittal STIR, and this one is labeled as a sagittal T1.

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When we look at T1-weighted images,

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what do we typically expect the marrow to look like on that sequence?

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Well, at this age, this is a teenager,

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she should have complete replacement of her marrow

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with a fatty marrow, there should be very little hematopoietic

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marrow in the metaphysis, and maybe a little bit in the tarsal bones.

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And here, fat should be nice and white, sort of like the fat you see over here.

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And this is white, but it's sort of a grayish white.

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It's not as white as it should be.

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You do see a little hematopoietic marrow

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over here, but it's not as white as we expect.

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The image on your left is a STIR sequence,

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Short Tau Inversion Recovery, which means that the fat is suppressed

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chemically and it should be dark and the fluid should be bright.

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In a regular sagittal T1 STIR image,

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this should all be dark because all of this is fatty marrow and fatty marrow

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should be suppressed and should become dark.

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The fact that it's so bright on STIR,

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means that the fatty marrow has essentially been replaced by fluid, okay?

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Or something very fluid-like.

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So some people have termed this as gelatinous transformation of the marrow,

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and some people just say there's a lot of fluid edema, whatever, in here.

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And if you also look,

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the patient has very, very little subcutaneous fat, right?

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So, it's affecting fat not also in the marrow, but also in the peri joint

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space in the subcutaneous tissue, deeper soft tissue.

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All of what you see that is bright is edema.

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So, that is what anorexia nervosa looks like.

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It causes this gelatinous transformation

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of the marrow, and it can be easily missed if you're not looking at your parameters.

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The sagittal STIR, again, should be nice and dark. But here, it's so bright.

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You know, other conditions can also cause this.

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You want to be sure that the patient doesn't have an underlying malignancy such

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as leukemia or lymphoma, other nutritional deficiencies.

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But when you see this in a teenage girl,

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dig deep in the chart and see if there is any psychiatric issues,

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is there any problems with body dysmorphism, and hopefully, what you look at

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can help you come up with the right diagnosis.