Combined diffusion and perfusion MRI with correlation to single-photon emission CT in acute ischemic stroke - Ischemic penumbra predicts infarct growth

Background and Purpose-More effective imaging methods are needed to overcom e the limitations of CT in the investigation of treatments for acute ischem ic stroke. Diffusion-weighted :MRI (DWI) is sensitive in detecting infarcte d brain tissue, whereas perfusion-weighted MRI (PWI) can detect brain perfu sion in the same imaging session. Combining these methods may help in ident ifying the ischemic penumbra, which is ain important concept in the hemodyn amics of acute stroke. The purpose of this study was to determine whether c ombined DWI and PWI in acute (<24 hours) ischemic stroke can predict infarc t growth and final size. Methods-Forty-six patients with acute ischemic stroke underwent DWI and PWI on days 1, 2, and 8. No patient received thrombolysis. Twenty-three patien ts underwent single-photon emission CT in the acute phase. Lesion volumes w ere measured from DWI, SPECT, and maps of relative cerebral blood flow calc ulated from PWI. Results-The mean volume of infarcted tissue detected by DWI increased from 46.1 to 75.6 cm(3) between days 1 and 2 (P<0.001; n=46) and to 78.5 cm(3) a fter 1 week (P<0.001; n=42). The perfusion-diffusion mismatch correlated wi th infarct growth (r=0.699, P<0.001). The volume of hypoperfusion on the in itial PWI correlated with final infarct size (r=0.827, P<0.001). The hypope rfusion volumes detected by PWI and SPECT correlated significantly (r=0.824 , P<0.001). Conclusions-Combined DWI and PWI can predict infarct enlargement in acute s troke. PWI can detect hypoperfused brain tissue in good agreement with SPEC T in acute stroke.