Improved diagnosis of early cerebral infarct by the combined use of diffusion and perfusion imaging

Purpose: to evaluate the feasibility and the diagnostic efficacy of multislice diffusion-weighted and perfusion imaging in addition to FLAIR-TSE, T(2)w-GraSE and MR-angiography in the diagnosis of acute stroke. Methods: 18 patients with acute stroke were examined at 1.5 Tesla (Gyroscan ACS-NT, Philips Medical Systems) within 6 (n=9) and 6-48 (n=9) hours, respectively, and followed at regular intervals. For diffusion imaging we used a multislice multishot EPI-SE sequence with navigator echo correction and cardiac gating. Perfusion imaging was done by means of a FFE-EPI sequence after bolus injection of Gd-DTPA. Results: The diagnostic value of diffusion-weighted and perfusion imaging was significantly higher compared with FLAIR-TSE (p=0.0023) and GraSE (p=0.0012) during the first 6 hours. With FLAIR-TSE and GraSE first pathologic changes were seen after 4 hours. We detected perfusion deficit (rCBV <10%) and a corresponding drop of the ADC in all infarcts larger than 1 cm in diameter. Within the area of low rCBV the combined analysis of diffusion and perfusion imaging allows to identify an infarct region with characteristics of a penumbra and one with characteristics of the infarct core,TTP was increased in the surrounding tissue. However, parts of this area were rarely included in the infarct. The final extension of the untreated infarct, as revealed by computed tomography, corresponded well to the perfusion deficit. Conclusions: Early ischaemic cerebral infarcts can be diagnosed with diffusion and perfusion imaging before pathological changes are visualized with other imaging modalities. The combined use may allow to distinguish the infarct core from surrounding, potentially salvageable tissue.