Abstract WMP38: Early Recurrent Infarction on Serial MRI in Symptomatic Intracranial Atherosclerotic Disease

Abstract

Background: MyRIAD is a prospective, multicenter, longitudinal observational study to determine the mechanisms of stroke recurrence in intracranial atherosclerotic disease (ICAD). Prior studies suggest that clinical endpoints of recurrent stroke in ICAD exceed 12% at 1 year despite medical management, whereas imaging evidence of early infarction remains largely unknown. We analyzed serial MRI from baseline to 6-8 week MRI in enrolled subjects to ascertain the rate of early infarction in ICAD. Methods: All MyRIAD subjects with DWI and FLAIR on qualifying or enrollment MRI followed by 6-8 week MRI were included. Olea Sphere ® 3.0 was used to co-register and align the serial DWI and FLAIR sequences at both timepoints. The presence of new DWI or FLAIR lesions of stroke in the symptomatic territory and DWI or FLAIR lesions outside the territory were determined by lesion mapping. Results: Serial MRI data were available in 60/80 (75%) of MyRIAD subjects enrolled to date, in whom target stenosis involved the middle cerebral (n=32), basilar (n=15), internal carotid (n=8) and vertebral (n=5) arteries. Between baseline and follow-up MRI, existing DWI lesions diminished in size (median -0.69 cc, IQR -2.69; n=58) while FLAIR lesions remained the same (median 0 cc, IQR -1.06; n=56). Outside the symptomatic territory, no new lesions were mapped on serial MRI with DWI or FLAIR. In the symptomatic territory, by 6-8 weeks there were discrete new lesions on DWI in 3/58 (5%) and 9/56 (16%) on FLAIR. Conclusions: Ischemic infarction in the symptomatic territory of ICAD may be evident on FLAIR and DWI early within the subacute phase. The mechanisms, clinical impact and potential prevention of these new ischemic lesions warrant further investigation.