Malignant bone marrow infiltration in nuclear magnetic resonance tomography

: Magnetic resonance imaging (MRI) is currently the only non-invasive method detecting changes of bone marrow. While yellow bone marrow produces a high signal intensity, which is similar to subcutaneous fat, any other cellular infiltration of the bone marrow causes a decrease of signal intensity because of replacement of marrow fat cells. In this report we describe two patients, who underwent MRI because of clinical symptoms of coxitis, in order to exclude Perthes disease. Both cases showed decreased signal intensity of the bone marrow particularly of the proximal femura, highly indicative of cellular bone marrow infiltration. Bone marrow aspiration in these patients showed acute lymphocytic leukemia in one case and marrow infiltration by neuroblastoma cells respectively in the other case. Because of its high sensitivity, MRI is also suitable in detecting focal bone marrow disease. For these cases a biopsy of these focal bone marrow lesions can be performed in order to stage the disease properly as in the presence of neuroblastoma or malignant lymphoma presenting with localized disease, however, with focal bone marrow metastases on MRI. In addition MRI can also be used to follow up the disease as well as therapy by showing the regression of these bone marrow lesions.