Perfusion-Based Relative Cerebral Blood Volume Is Associated With Functional Dependence in Large-Vessel Occlusion Ischemic Stroke

Abstract

Background: Pretreatment computed tomography perfusion parameter relative cerebral blood volume (rCBV) lesion volume has been shown to predict 90-day modified Rankin Scale score in small-core strokes with Alberta Stroke Program Early Computed Tomography Score ≥5, including those with medium-vessel occlusions (mid and distal M2 segment occlusions). Hence, in this study we aim to assess the performance of different rCBV lesion volume thresholds (rCBV <42%, rCBV <38%, and rCBV <34%) with 90-day modified Rankin Scale score including patients with large core (Alberta Stroke Program Early Computed Tomography Score <5) and strictly including only patients with anterior circulation large-vessel occlusion.

Methods and results: In this retrospective evaluation of our prospectively collected database, inclusion criteria were (1) Computed tomographic angiography confirmed anterior circulation large-vessel occlusion from September 1, 2017, to October 1, 2023; and (2) diagnostic computed tomography perfusion. Student t test, Mann-Whitney U test, and χ² test were used in the univariate data analysis. Spearman's rank correlation analysis was used to assess correlations. Outcome measure was dichotomized into good functional outcome (90-day modified Rankin Scale score, 0-2) and poor functional outcome (90-day modified Rankin Scale score, 3-6) for logistic regression and receiver operating characteristic analysis. P≤0.05 was considered significant. In total, 229 patients met our inclusion criteria. The majority of the patients (n=161) in our cohort had M1 occlusion. All the rCBV thresholds were significantly higher in patients with poor 90-day functional outcomes and were independently associated with the outcome. Spearman's rank correlation analysis revealed a slightly stronger correlation of rCBV <42% (ρ=0.27, P<0.001), as compared with rCBV <38% (ρ=0.25, P<0.001) and rCBV <34% (ρ=0.24, P<0.001) with functional outcome. Receiver operating characteristic analysis revealed that rCBV <42% (area under the curve, 0.67 [95% CI, 0.60-0.74]; P<0.001) performed marginally better than rCBV <38% (area under the curve, 0.66 [95% CI, 0.59-0.73]; P<0.001), and rCBV <34% (area under the curve, 0.65 [95% CI, 0.58-0.72]; P<0.001).

Conclusions: All the rCBV thresholds were independently associated with poor 90-day functional outcome; however, the rCBV <42% marginally outperformed rCBV <38% and rCBV <34% lesion volumes.

Keywords: poor functional outcome; rCBV <42%; relative cerebral blood volume.

Figure 1. Distribution of rCBV thresholds in patients with poor (90‐day mRS score, 3–6) and good functional outcomes (90‐day mRS score, 0–2) at 90 days.

Box and whisker plot distribution of rCBV <42% (A), rCBV <38% (B), and rCBV <34% (C) lesion volume in patients with a poor 90‐day mRS score of 3 to 6 and with a good 90‐day mRS score of 0 to 2. Box plot represents median and interquartile range, whereas whiskers represent minimum and maximum values. Y axis represents volume in mL. mRS indicates modified Rankin Scale; and rCBV, relative cerebral blood volume.

Figure 2. ROC curve analysis of rCBV lesion volume thresholds in predicting poor functional outcomes (defined as mRS score, 3–6 at 90 days).

The rCBV <42% lesion volume (AUC, 0.67 [95% CI, 0.60–0.74]; P<0.001) performed better than rCBV <38% (AUC, 0.66 [95% CI, 0.59–0.73]; P<0.001) and rCBV <34% (AUC, 0.65 [95% CI, 0.58–0.72]; P<0.001) lesion volume in predicting 90‐day functional outcome. AUC indicates area under the curve; mRS, modified Rankin Scale; rCBV, relative cerebral blood volume; and ROC, receiver operating characteristic.