Combined perfusion- and diffusion-weighted MR imaging in acute ischemic stroke during the 1st week: A longitudinal study

PURPOSE: To compare findings with different magnetic resonance (MR) perfusion maps in acute ischemic stroke. MATERIALS AND METHODS: Combined diffusion-weighted (DW) and perfusion-weighted (PW) MR imaging was performed in 49 patients with acute (<24 hours) stroke, on the ist and 2nd days and 1 week after stroke. Volumes of hypoperfused tissue on maps of relative cerebral blood volume (rCBV), relative cerebral blood flow (rCBF), and mean transit time (MTT) were compared with the volume of infarcted tissue at DW imaging. RESULTS: The mean infarct Volume increased from 41 to 65 cm(3) between the ist and 2nd days (P < .001; n = 49). On the 7st day, all perfusion maps on average showed hypoperfusion lesions larger than the infarct at DW imaging (P < .001; n = 49). MTT maps showed significantly (P < .001) larger hypoperfusion lesions than did rCBF maps, which showed significantly (P < .001) larger hypoperfusion lesions than did rCBV maps. The sizes of the initial perfusion-diffusion mismatches correlated significantly with the extent of infarct growth (0.479 < r < 0.657; P <less than or equal to> .001). The hypoperfusion volume on the initial rCBV maps correlated best with the final infarct size at 1 week (r = 0.891; P < .001). CONCLUSION: Combined DW and PW imaging is a powerful tool in evaluating the hemodynamics of acute ischemic stroke.