Defining the prognostic performance of multiphase CT-angiography in ischemic stroke patients

BACKGROUND: The prognostic performance of multiphase CT-angiography (mCTA) in ischemic stroke patients undergoing endovascular treatment (EVT) in the early and late treatment window remains poorly characterized. METHODS: Data derived from two prospective EVT registries. The primary outcome was functional independence (90-day modified Rankin Scale ≤2). Secondary outcomes included excellent prognosis (90-day mRS ≤ 1), 90-day ordinal mRS, and follow-up infarct volume (FIV) on 24-hour non-contrast CT. Associations between mCTA collateral status and outcomes were assessed with binary, ordinal, or linear logistic regression analyses as appropriate. The prognostic performance was evaluated with the c-statistic. The optimal cutoff for mCTA collaterals, assessed using the Menon grading system (0-5), was identified using the Youden Index. The same analyses were conducted in subgroups based on reperfusion status, CT-reperfusion time, and treatment windows. RESULTS: 1220 patients were included: median age was 74 years [IQR = 67-84], 647 (53.0%) were females, and 593 (48.6%) achieved functional independence. Functional independence was associated with mCTA collaterals (adjusted odds ratio [aOR] 2.09 [95%CI = 1.75-2.50] per each 1-point score increase). The c-statistic of mCTA collaterals for predicting functional independence was 0.68 (95%CI = 0.65-0.71). The optimal cutoff value for mCTA collaterals in predicting functional independence was ≥ 4. Collaterals evaluated by mCTA, per each 1-point increase, were associated with excellent outcome (aOR 1.87 [95%CI = 1.54-2.26]), ordinal mRS (acOR 0.60 [95%CI = 0.51-0.69]), and FIV (aß -20.25 [95%CI=-(26.46;14.05)]. Results were consistent in subgroup analyses. CONCLUSION: Collateral status evaluated by mCTA was strongly associated with clinical outcomes and FIV, and a specific cutoff of 4 was shown to predict functional independence.