Abstract Number: Esoc2026ys263 Cortical Dwi-Positive Infarcts Can Have Negative Ct Perfusion: Clinical Predictors in a Two-Centre Cohort

Background and aims Small deep white matter infarcts, particularly in the posterior circulation, are recognised causes of false-negative CT perfusion (CTP). In contrast, little is known about CTP negativity in patients with cortical infarction. We evaluated determinants of CTP negativity in a DWI-positive cohort and performed a focused analysis of cortical-only infarcts. Methods Retrospective study of consecutive clinical CTP (October 2024–December 2025) from two acute stroke centres. Patients were included if MRI was performed within 7 days of CTP (≤8 calendar days) and was diffusion-weighted imaging (DWI) positive, with radiology extracted from a structured proforma. Primary modelling compared negative vs positive CTP (excluding wrong-territory CTP). A cortical-only subgroup was defined as MRI main lesion location “cortical” with the biggest lesion in frontal/parieto-temporal/occipital regions (fig 1). Multivariable logistic regression used 5-fold cross-validation (AUC, 95% CI). Results Of 722 CTP studies, 268 had MRI within 8 days; 159 were DWI positive. For negative vs positive CTP, AUC improved from 0.692 (0.518–0.865) using clinical variables to 0.777 (0.613–0.941) after adding MRI phenotype variables. In the cortical-only subgroup (n=42; 18 negative vs 24 positive CTP), negative CTP was independently associated with diabetes (adjusted OR 66.73 (2.41–1845.36); p=0.015) and lower/absent NIHSS Visual field/Gaze deviation burden (adjusted OR 0.367 (0.150–0.898),; p=0.027). Conclusions Beyond the recognised posterior deep infarct phenotype, cortical DWI-positive infarcts can also be CTP-negative, particularly in patients with diabetes and milder visual/gaze deficits. TAKE-HOME A negative CTP does not exclude cortical infarction—clinical phenotype still matters. Conflict of interest Kausik Chatterjee: nothing to declare, Adam Seed: nothing to declare; Fathalla Elnagi: nothing to declare; NANA GYIMAH-KESSIE: nothing to declare Figure 1 - belongs to Methods Figure 2 - belongs to Results