Visual versus Automated CT Perfusion for Outcome Prediction in Anterior Circulation Stroke Treated with Mechanical Thrombectomy

Abstract

Background
The prognostic value of simple visual assessment of CT perfusion (CTP) for predicting clinical outcomes has already been demonstrated in anterior circulation stroke patients undergoing mechanical thrombectomy (MT). Automated software, however, has become the dominant method of perfusion evaluation in clinical practice and clinical trials. We compared the prognostic accuracy of visually grading CTP maps with automated CTP analysis on clinical outcomes in anterior circulation stroke patients treated with MT.

Methods
In a single centre we retrospectively analysed consecutive patients with anterior circulation large-vessel occlusion treated with MT between 2013 and 2020. Baseline imaging included non-contrast brain CT, CT angiography with collateral assessment and CTP. Time to peak (TTP) maps were visually graded on a four-level ordinal scale based on estimated penumbra. Automated CTP was processed with syngo.via (SYV) using default thresholds and classified on a comparable ordinal scale. The primary endpoint was favourable 90-day functional outcome (Rankin Scale (mRS) ≤ 3). Analyses included direct comparisons of the two CTP techniques, univariate associations with functional outcome and multivariable logistic regression adjusted for age, intravenous thrombolysis (IVT), ASPECTS, time to groin puncture, success of recanalization (TICI ≥ 2b) and CTA collateral status (CS).

Results

We included 579 patients (mean age 70.8 years; 51.5% male), of which 81% achieved TICI ≥ 2b and 45% received IVT. 61.9% of patients had favourable outcome. Agreement between visual and automated CTP was fair (κ = 0.36). Both methods were significantly associated with favourable outcome (p < 0.01), with visual grading showing a slightly stronger association (Pearson χ² = 30 vs. 22). In multivariable models, visual CTP remained an independent predictor, whereas automated CTP lost significance when CS was included.

Conclusions

Visual CTP grading of TTP maps provided a slightly better prognostic performance than automated CTP evaluated by SYV using default settings. Visual CTP assessment is a simple, accessible and clinically meaningful tool for both treatment decision making and outcome prediction in anterior circulation stroke treated with MT.

Key words: CT perfusion, acute stroke, mechanical thrombectomy, prognosis