Angiographic Success Does Not Fully Reflect Tissue-Level Reperfusion: New Diffusion-Weighted Imaging Lesions After True Complete (TICI 3) Recanalization

Background and Purpose: Complete angiographic reperfusion (TICI 3) is considered the optimal procedural endpoint of mechanical thrombectomy (MT) in acute ischemic stroke. However, new diffusion-weighted imaging (DWI) lesions are frequently observed despite apparent angiographic success. We aimed to investigate the incidence, morphological patterns, and clinical relevance of these lesions in a strictly defined TICI 3 cohort. Methods: In this retrospective single-center study, 89 patients with anterior circulation large-vessel occlusion (LVO) who achieved true TICI 3 were analyzed. Baseline and follow-up Magnetic Resonance Imaging (MRI) within 48 h were systematically compared using paired diffusion-weighted imaging (DWI) and apparent diffusion coefficient (ADC) maps to identify new lesions. Lesions were classified according to morphology and distribution. Stroke etiology was assessed using TOAST criteria. Functional outcomes were evaluated using the 90-day modified Rankin Scale (mRS) with the Rankin Focused Assessment. Results: New DWI lesions were detected in 28 of 89 patients (31.5%). The predominant pattern was millimetric cortical foci (85.7%), most frequently ipsilateral to the recanalized vessel (78.6%), with fewer contralateral (14.3%) and bilateral (7.1%) lesions. Territorial infarcts and isolated basal ganglia infarcts were each identified in 14.3% of patients, with some overlap between categories. No significant differences were observed between patients with and without new lesions regarding baseline characteristics or procedural metrics (all p > 0.05). Importantly, the presence of new DWI lesions was not associated with 90-day functional outcome (p = 0.930) or survival (p = 0.613). Conclusions: New DWI lesions are common even after complete angiographic reperfusion, highlighting a persistent dissociation between macrovascular success and tissue-level integrity. Although predominantly small and clinically silent in the short term, these findings underscore the limitations of angiographic endpoints alone and support the need for strategies targeting microvascular protection and prevention of distal embolization.