MULTISLICE DIFFUSION MAPPING FOR 3-D EVOLUTION OF CEREBRAL-ISCHEMIA IN A RAT STROKE MODEL

Diffusion-weighted magnetic resonance imaging (DWI) can quantitatively demonstrate cerebral ischemia within minutes after the onset of ische mia. The use of a DWI echo-planar multislice technique in this study a nd the mapping of the apparent diffusion coefficient (ADC) of water, a reliable indicator of ischemic regions, allow for the detection of th e three-dimensional (3-D) evolution of ischemia in a rat stroke model. We evaluated 13 time points from 5 to 180 minutes after occlusion of the middle cerebral artery (MCA) and monitored the 3-D spread of ische mia. Within 5 minutes after the onset of ischemia, regions with reduce d ADC values occurred. The core of the lesion, with the lowest absolut e ADC values, first appeared in the lateral caudoputamen and frontopar ietal cortex, then spread to adjacent areas. The volume of ischemic ti ssue was 224 +/- 48.5 mm(3) (mean +/- SEM) after 180 minutes, ranging from 92 to 320 mm(3). and this correlated well with the corrected infa rct volume at postmortem (194 +/- 23.1 mm(3), r = 0.72, p < 0.05). Thi s experiment demonstrated that 3-D multislice diffusion mapping can de tect ischemic regions noninvasively 5 minutes after MCA occlusion and follow the development of ischemia. The distribution of changes in abs olute ADC values within the ischemic region can be followed over time, giving important information about the evolution of focal ischemia.