Friday, May 9, 2008

Red Marrow and Lady Chatterly's Lover

"Oh literature, oh the glorious Art, how it preys upon the marrow in our bones. It scoops the stuffing out of us, and chucks us aside. Alas!" - D.H. Lawrence

Overheated language is to be expected from D.H. Lawrence, the author of the novel Lady Chatterly's Lover. Hard as it is to believe, this novel was once regarded as pornographic, in a long gone era. These days it can be found in most community libraries:

Radiologists look at bone marrow all the time. Marrow does not scoop up even a soup├žon of stuffing out of me, since I am too busy trying to make sure that it is normal. Marrow is evaluated primarily on T1-weighted, T2 fat suppressed, and STIR images. Most of us tend screen the marrow quickly using STIR or T2 fat suppressed images, since most marrow abnormalities tend to be bright on these images.

Occasionally your eye will be drawn to marrow that looks more hyperintense than typical. Forty-nine year old female, imaged for elbow pain:

(A) Coronal T2 fat sat and (B) T1-weighted images depict areas of differential signal within the radius. These areas are hyperintense on T2 fat sat images (red arrow); corresponding areas are decreased in signal on T1-weighted images (green arrows).

Does this patient have an infiltrating process in the marrow such as a tumor, or perhaps bone marrow edema from trauma or ischemia? If the radiologist raises such possibilities, alarm bells will ring, with patient anxiety and referring clinician consternation resulting.

Fortunately, these areas of differential signal simply represent red marrow, and are not pathologic. Areas of red marrow should not be confused with bone marrow edema.

The different signal of red and yellow marrow is a result of the higher water content of red marrow. Adults will have variable amounts of red marrow, and these areas can be quite prominent, particularly in the metaphysis of long bones. Red marrow is typically amorphous and feathery in character on T1-weighted images. On fluid-sensitive images, red marrow is isointense or minimally hyperintense to skeletal muscle, and can be flame-shaped. These features, and the metaphyseal and metadiaphyseal location of red marrow is a strong clue to the benign diagnosis. Red marrow is classically prominent in the setting of smoking and obesity, particularly in middle-aged female patients.

Overcalling red marrow can be hazardous to your radiology reputation- it's a good idea to become familiar with its appearance.

Vic David MD

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