ANALYSIS OF INTRAMEDULLARY CELL-DENSITY BY MRI USING THE MULTIPLE SPIN-ECHO TECHNIQUE

Analysis of the intramedullary cell distribution by magnetic resonance imaging (MRI) using conventional techniques involves subjectively int erpreting images and estimating the cell distribution on the basis of signal intensity characteristics. In recent years, attempts have been made to achieve more precise analysis by new techniques, including che mical shift imaging. The multiple spin-echo (MSE) technique offers som e advantages over conventional MRI. Since it allows measurement of the transverse magnetization decay curve at 32 or more points, it is capa ble of separating several tissue components with different relaxation times. In addition, this technique can be used with MRI instruments ha ving a static magnetic field as low as 1.0 Tesla, In the present study , the intramedullary cell density was assessed by MRI using the MSE te chnique in 4 patients with aplastic anemia (AA), 4 patients with myelo dysplastic syndrome (MDS), and 5 normal subjects. The water component of the marrow (with a short relaxation time) and the fat component (wi th a long relaxation time) were separated from each other by analyzing MR images obtained using the MSE technique, and the signal intensity ratio of the 2 components was calculated. The ratio was significantly higher in the AA group than in the other groups (AA vs. MDS, P = 0.020 9, AA vs, normal controls, P = 0.0143). The present technique appears promising for quantitative assessment of the intramedullary cell densi ty. (C) 1997 Wiley-Liss, Inc.