ApoE polymorphism and acute stroke: a study with diffusion- and perfusion-weighted MRI and MR angiography

Objectives – We examined whether the apolipoprotein E (ApoE) allele ɛ4 influences imaging findings in stroke as assessed by diffusion- (DWI) and perfusion-weighted (PWI) magnetic resonance imaging, and MR angiography (MRA). Methods – Eight ApoE ɛ4 carriers and 15 non-carriers with acute ischemic stroke in the anterior circulation underwent DWI, PWI, and MRA within 24 h of stroke. DWI and PWI were repeated a week later. The apparent diffusion coefficient, relative cerebral volume (rCBV), relative cerebral blood flow (rCBF) and relative mean transit time were measured in three subregions on day one. Results – In the ischemic core and the area of infarct growth, rCBV values were significantly higher in the ɛ4 carriers compared with the non-carriers. Based on the MRA findings, collateral blood flow was better in the ɛ4 carriers than in the non-carriers. Under the comparable severity of hypoperfusion, the hypoperfused area proceeded to infarction later or did not proceed to infarction at all in the non-carriers. Conclusion – These preliminary data suggest that in the ApoE allele ɛ4 carriers the threshold for the brain tissue to survive hypoperfusion versus to proceed to infarction seems to be different from that of the non-carriers.