INITIAL EXPERIENCE WITH DYNAMIC MR-IMAGING IN EVALUATION OF NORMAL BONE-MARROW VERSUS MALIGNANT BONE-MARROW INFILTRATIONS IN HUMANS

The purpose of this study was (a) evaluation of dynamic contrast-enhan ced MR imaging of normal bone marrow versus malignant bone marrow infi ltrations in patients with proven B-cell-type chronic lymphocytic leuk emia (B-CLL) and (b) correlation with the clinical stage according to Binet (stages A, B, C) and response to therapy. Bone marrow imaging of the lumbar spine, pelvis, and proximal femurs was performed at 1.5 T in 45 patients without known malignancy and in 30 patients with B-CLL. The differences between opposed-phase and in-phase dynamic gradient-e cho sequences before and up to 10 minutes after intravenous applicatio n of .1 mmol/kg body weight of gadolinium-diethylenetriamine penta-ace tic acid (Gd-DTPA) were evaluated in normal bone marrow. The contrast- enhancement patterns of normal and malignant bone marrow were compared using the opposed-phase dynamic gradient-echo sequence. Ten of the pa tients with bone marrow infiltrations (Binet stage C) additionally und erwent MR imaging follow-up during therapy. Opposed-phase gradient ech o sequences demonstrated a signal decrease of normal bone marrow, and in-phase gradient echo sequences demonstrated a signal increase of nor mal bone marrow after administration of Gd-DTPA. The dynamic signal in tensity time courses differed significantly (P < .05) between Binet st ages B and C and controls as well as among the three Binet stages of B -CLL. In the 10 patients followed during therapy, MR imaging sensitive ly demonstrated response (n = 6), nonresponse (n = 2), or relapse afte r initial response (n = 2). In out-of-phase imaging, both normal bone marrow and initial bone marrow infiltration in CLL stage Binet A show signal decrease after administration of contrast agent, whereas there is increase in signal intensity in higher-grade bone marrow infiltrati on in Binet stage B or C disease. The signal loss of normal bone marro w in out-of-phase imaging is a phase effect rather than a T2 effect. The differentiation of initial from higher-grade bone marrow infiltrat ion on out-of-phase images relies solely on a shift in the fat/water r atio.