Proton MR Imaging and Spectroscopy Evaluation of Aplastic Anemia: Three Bone Marrow Patterns

PURPOSE: The purpose of this study was to classify bone marrow intensity patterns in aplastic anemia with proton MRI and to compare them with MR spectroscopic findings quantitatively and qualitatively. METHOD: Twelve patients with aplastic anemia and six normal volunteers were examined with a 1.5 T MR unit. T1-weighted SE, fast STIR, and opposed-phase T1-weighted RF-spoiled GE images (op-SPGR) were acquired with MR images, while MR spectroscopy was performed with a stimulated echo acquisition mode without water suppression. RESULTS: Three bone marrow patterns were determined in aplastic anemia with MR images: marrow a with low intensity on fast STIR and high intensity on T1-weighted imaging and op-SPGR, marrow b with low intensity on T1-weighted imaging and op-SPGR and high intensity on fast STIR, and marrow c with low intensity on T1-weighted imaging and high intensity on fast STIR and op-SPGR. MR spectroscopy quantitatively showed that the ratio of water to fat of marrow a significantly decreased (mean 0.41) and that of marrow c increased (mean 3.40) compared with those of marrow b (mean 1.09) and normal bone marrow (mean 1.04). There were no differences of the types of fat signals between aplastic anemia and normal bone marrow with MR spectroscopy. CONCLUSION: MR imaging and spectroscopy were noninvasive methods of classifying bone marrow patterns and quantifying bone marrow content in aplastic anemia, which may improve the results currently obtained with biopsy.