Purpose or Case Report: Bone marrow is composed of fat and cellular elements supported by the trabecular bone. Pathological lesions of the bone marrow usually replace its normal constituent to a variable degree. Differentiation among traumatic, neoplastic, and inflammatory processes of the bone marrow is often not possible with MRI, which commonly requires the patient to undergo additional invasive diagnostic procedures to obtain an accurate diagnosis.

In-phase and opposed-phase imaging has been used extensively in imaging of the liver and adrenal glands. However, recently it has been introduced into the evaluation of the bone marrow. The technique takes advantage of different excitation frequencies of water and fat protons due to differences in their molecular environments. The main concept is that the presence of normal bone marrow would result in suppression of signal intensity on the opposed-phase images. In the presence of infiltration lesions of the bone marrow, normal fat-containing marrow will be replaced with neoplastic cells and result in lack of suppression on the opposed-phase images.

The main teaching purpose of this exhibit will be to demonstrate, by a pictorial case-based review, the appearance of multiple cases of biopsy-proven infiltrating lesions of the bone marrow, and emphasize how they can be differentiated from other traumatic or inflammatory processes.

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