ABSTRACT NUMBER: ESOC2026A2317 DIAGNOSTIC IMPACT OF INTRACRANIAL VESSEL WALL MRI ON ISCHEMIC STROKE ETIOLOGY IN YOUNG ADULTS

Abstract Background and aims Determining ischemic stroke etiology remains challenging in younger patients. Intracranial vessel wall MRI (VWI) enables direct visualization of vessel wall pathology beyond conventional imaging. We evaluated the diagnostic contribution of VWI to etiologic classification in young patients with ischemic stroke. Methods In this prospective substudy of the Estonian Young Stroke Registry, consecutive patients aged 18 to 59 years with MRI-confirmed ischemic stroke in the middle cerebral or anterior choroidal artery territory underwent contrast-enhanced VWI. VWI studies were independently assessed by two neuroradiologists and stroke etiology was classified according to TOAST criteria by two blinded stroke neurologists before and after VWI, with discrepancies resolved by consensus. Results Fifty-eight patients were included (71% male; median age 53 years, interquartile range 47–56). Overall, incorporation of VWI led to etiologic reclassification in 8 patients (14%). After VWI, the proportion of large artery atherosclerosis increased from 19% to 29%, while cardioembolism decreased from 35% to 31%, lacunar stroke from 19% to 17%, and cryptogenic stroke from 19% to 12%. Among patients with cryptogenic stroke prior to VWI, etiologic diagnosis changed in 5 patients (46%). Cryptogenic stroke before VWI predicted etiologic reclassification after adjustment for age and sex (p = 0.033). Interrater agreement was good among neuroradiologists (κ = 0.72, 95% CI 0.55–0.88) and very good among neurologists (κ = 0.82, 95% CI 0.70–0.93). Conclusions VWI provides additional etiologic information beyond conventional imaging and can be useful as a second-line imaging modality in young patients with cryptogenic ischemic stroke. Conflict of interest Siim Schneider: nothing to disclose. Juhan Reimand: nothing to disclose. Riina Vibo: nothing to disclose. Liisa Kõrv: nothing to disclose. Dagmar Loorits: nothing to disclose. Karl Jõgi: nothing to disclose. Teele Tuularu: nothing to disclose. Kateriine Orav: nothing to disclose. Janika Kõrv: nothing to disclose.