Systematic review and meta-analysis on neuroimaging biomarkers for futile recanalization in stroke thrombectomy

BACKGROUND: Mechanical thrombectomy (MT) has transformed the management of large vessel occlusion stroke; however, a considerable proportion of patients fail to achieve functional recovery despite successful recanalization. This futile recanalization underscores the need to better understand imaging biomarkers that may predict poor outcomes after endovascular therapy. PURPOSE: To systematically review and synthesize evidence on neuroimaging biomarkers associated with futile recanalization after MT in acute ischemic stroke. DATA SOURCES: PubMed, Scopus, Web of Science, and EMBASE databases were searched up to March 2025, supplemented by manual reference screening. STUDY SELECTION: Eligible studies enrolled adult patients with anterior-circulation stroke who underwent thrombectomy, reported pretreatment neuroimaging findings, and evaluated functional outcomes despite successful reperfusion. Case reports, reviews, abstracts, and nonhuman studies were excluded. DATA ANALYSIS: Two reviewers independently screened, extracted data, and assessed study quality using the Prediction Model Risk of Bias Assessment Tool. Random-effects meta-analysis was performed where appropriate. Heterogeneity, publication bias, and sensitivity analyses were undertaken. DATA SYNTHESIS: Fifty-one studies were included. Lower ASPECTS scores were strongly associated with futile recanalization (OR = 0.81). Core infarct volume showed inconsistent associations, whereas perfusion and collateral markers, including elevated hypoperfusion intensity ratio, delayed venous outflow, and poor collateral scores, demonstrated strong predictive value. Chronic white-matter injury, leukoaraiosis, and cerebral atrophy were also consistently associated with worse outcomes. LIMITATIONS: Limitations included heterogeneity in imaging protocols and thresholds; predominance of retrospective single-center cohorts; limited direct comparison across imaging modalities; and variable adjustment for confounders. CONCLUSIONS: Neuroimaging biomarkers, particularly ASPECTS, perfusion-derived metrics, collateral status, and markers of chronic small vessel disease, provide important prognostic information for identifying patients at risk of futile recanalization despite successful thrombectomy.