ABSTRACT NUMBER: ESOC2026A2173 CLINICAL AND RADIOLOGICAL CHARACTERISTICS OF AIS PATIENTS WITH NO PERFUSION LESIONS ON ADMISSION CTP

Abstract Background and aims CTP has high specificity for cerebral ischaemia but limited spatial resolution reduces sensitivity for small volume lesions including lacunar infarcts. We explored the clinical and radiological characteristics of perfusion-imaging negative AIS in patients undergoing CTP<24 hours from last known well. Methods We analysed admission NCCT, CTP and CTA and 24-72h follow-up MRI from patients imaged <24h after symptom onset from a prospective, observational, single-centre study. NCCT and CTA were scored by two blinded assessors. LVO was defined as ICA, M1 or >2 branch M2 occlusion. CTP was processed by RAPID (version 4.7 Ischemaview). We defined penumbra (Tmax>6s and relative Cerebral Blood Flow rCBF>30%) and core (rCBF<30%). Follow-up infarct volumes (FIV) were calculated from manually outlined DWI lesions in MANGO (UTHSCSA version 4.0.1). Results Of 185 patients recruited, 146 had complete imaging suitable for analysis. Final diagnosis was AIS/TIA in 139 and non-stroke in 7 (figure 1). Table 1 outlines baseline details. Among 139 patients with final diagnosis of AIS/TIA, 47 (34%) had no perfusion deficit of which 45 (32%) had a DWI lesion. 4 (3%) patients had multiple DWI lesions and 41 (29%) patients had 1 lesion of which 9 (6%) were lacunar, 4 (3%) sub-cortical and 29 (21%) cortical. No CTP lesion patients had significantly lower admission and follow-up NIHSS, later onset to CTP imaging and smaller DWI lesions (Kruskal-Wallis p=0.002, 0.006,<0.001 and <0.001 respectively). Conclusions Our data show that patients with no CTP deficit have clinical and radiological features of minor stroke and predominantly small cortical DWI lesions. Conflict of interest Viveka Biswas: nothing to disclose, Sam Neilson: nothing to disclose, Amith Sitaram: nothing to disclose, Christopher Pollard: nothing to disclose, Wazim Izzath: speakership for Acandis, Keith W Muir: grants from the British Heart Foundation, Innovate UK, Chief Scientist Office, The Stroke Association and the National Institute of Health Research; consultancy agreements with Boehringer Ingelheim, Abbvie; advisory boards for Boehringer Ingelheim, Abbvie and Biogen; speaker’s fees from Boehringer Ingelheim. Figure 1 - belongs to Methods Table 1 - belongs to Results