| Research Abstract |
1) PURPOSE : For the assessment of the composition and state of brain edema, the diffusion behavior of intracranial water in the operated rat brain was examined with the use of diffusion-weighted MR imaging sequence. We adopted in this study, the cross-relaxation imaging in which evaluating the free- and protein- bound water and T1-weighted imaging in which evaluating the intracranial water contents and blood brain barrier function, with the rat model of infarction by middle cerebral artery occlusion (MCAO).
2) MATERIAL AND METHODS : Special care was taken to ensure that the rats were firmly restrained and positioned in the head coil and probe. The core thermotemperature of all rats was maintained at 37℃. After MCAO operation, rats were decapitated and the brains were processed for histological examination by myelin staining and fibrinogen immunostaining.
3) RESULT : Control rat ; MT ratio(%)(SD), rt.27.1 (1.3) lt.26.7 (1.0), T1 time (msec) rt.607.8 (1.6) lt.615.4 (2.8), FW, rt.0.67, lt.0.68, no apparent differences (p>0.05), MCAO rat ; MT ratio (%)(SD), rt.33.8 (2.0), lt. 28.9 (1.0), T1 time (msec), rt.615.5 (0.9), lt.694.7 (1.9), FW, rt.0.68, lt.0.71. Significantly different between rt. and lt. (p<0.01) ; FW (water weight/ total brain weight)=1/ (0.921+0.341/T1 time) (1.5Tesla), by PP Fatouros, et al. J.Neurosurg 90 : 109 - 115, 1999. Histologically, the examined brains contained infarction of MCAO area of the cortex and subcortical demyelination.
4) DISCUSSION : The decrease of MT ration can be derived from the increase of free water, exceed the protein-bound water. Utilization of this MR imaging technique to determine the orientation of intra-cranial water through measurement of water proton apparent diffusion has the potential to greatly improve our understanding and assessment of brain edema.
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