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) perfusi on maps in acute ischemic stroke. MATERIALS AND METHODS: Combined diffusion-weighted (DW) and perfusion-weigh ted (PW) MR imaging was performed in 49 patients with acute (<24 hours) str oke, on the ist and 2nd days and 1 week after stroke. Volumes of hypoperfus ed tissue on maps of relative cerebral blood volume (rCBV), relative cerebr al blood flow (rCBF), and mean transit time (MTT) were compared with the vo lume 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 hypoper fusion lesions than did rCBF maps, which showed significantly (P < .001) la rger hypoperfusion lesions than did rCBV maps. The sizes of the initial per fusion-diffusion mismatches correlated significantly with the extent of inf arct growth (0.479 < r < 0.657; P <less than or equal to> .001). The hypope rfusion volume on the initial rCBV maps correlated best with the final infa rct 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.