DIFFUSION-WEIGHTED ECHO-PLANAR MRI OF LACUNAR INFARCTS

We studied 35 patients with lacunar infarcts, using diffusion-weighted echo-planar imaging (DW-EPI) at 1.5 T. The relative apparent diffusio n coefficient ratio (ADCR) of each lesion was calculated and lesion co nspicuity on DW-EPI was compared to that on images aquired with fast f luid-attenuated inversion recovery and T2-weighted fast spin-echo sequ ences. Acute small infarcts (within 3 days) were identified with DW-EP I as an area of decreased ADCR (range 0.33-0.87; mean 0.67) and high s ignal, subacute small infarcts (4-30 days) as a high-signal or isointe nse areas of decreased or nearly normal ADCR (0.54-0.98; 0.73), and ch ronic small infarcts (> 30 days) as low- or high-signal areas of nearl y normal or increased ADCR (0.97-1.92; 1.32). In three patients, small infarcts of the brain stem in the hyperacute phase (within 6 h) were seen only with DW-EPI. In five patients, fresh small infarcts adjacent to multiple old infarcts could be distinguished only with DW-EPI.