Predicting futile recanalization before mechanical thrombectomy: the added value of CT imaging markers.

Purpose: To evaluate the incremental value of computed tomography (CT) imaging markers beyond clinical factors in predicting futile recanalization (FR) in patients with acute ischemic stroke (AIS) undergoing mechanical thrombectomy (MT), and to develop an integrated clinical-imaging nomogram for FR risk stratification.

Methods: We enrolled 342 AIS patients who achieved successful recanalization-definded as a modified Thrombolysis in Cerebral Infarction grade ≥ 2b after MT-between October 2019 and December 2023. FR was defined as a poor outcome (modified Rankin Scale score 3-6) despite successful recanalization. Independent clinical and imaging predictors of FR were identified by multivariable logistic regression. The added value of CT imaging markers was assessed using integrated discrimination index (IDI) and continuous net reclassification improvement (NRI). Significant predictors were incorporated into a nomogram, and its discrimination and calibration were assessed.

Results: FR was observed in 161 patients (47.1%) at 90 days. Independent predictors of FR included older age, female sex, diabetes, higher National Institutes of Health Stroke Scale (NIHSS) scores, higher net water uptake (NWU), lower Alberta Stroke Program Early CT Score (ASPECTS) and unfavorable comprehensive venous outflow (CVO) score (all p < 0.05). Incorporating imaging markers (ASPECTS, NWU, and CVO score) significantly improved the discriminatory performance of the clinical model (IDI: +14.2%; NRI: +82.5%; both p < 0.001 ). Decision curve analysis confirmed the clinical utility of the integrated nomogram.

Conclusion: CT imaging markers from Non-contrast CT (NCCT) and CT angiography (CTA) enhance FR risk prediction when added to clinical factors. The integrated nomogram may support individualized treatment decision-making in AIS patients prior to MT.