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Updated: Jun 24, 2026
A Thrombotic Stroke Model Based On Transient Cerebral Hypoxia-ischemia
Published on: August 18, 2015
Hypoperfusion Intensity Ratio Correlates with CTA Collateral Status in Large-Vessel Occlusion Acute Ischemic Stroke
D Lyndon1,2, M van den Broek1,2, B Niu3
1Neuroradiology Division (D.L., M.v.d.B., A.R., F.S.), Vancouver General Hospital, Vancouver, British Columbia, Canada.
Insights
The hypoperfusion intensity ratio, an automated CTP measure, accurately reflects collateral status in large-vessel occlusion stroke, offering a quantitative alternative to subjective CTA scoring for improved stroke assessment.
Area of Science:
- Neurology
- Radiology
- Medical Imaging
Background:
- Collateral blood supply is crucial for outcomes in large-vessel occlusion acute ischemic stroke.
- Current collateral scoring systems using CT angiography (CTA) are subjective and require specialized training.
Purpose of the Study:
- To evaluate the association between the CTP-derived hypoperfusion intensity ratio and CTA collateral status.
- To determine if a hypoperfusion intensity ratio threshold can predict poor CTA collaterals.
Main Methods:
- Retrospective review of imaging and clinical data from 52 patients with large-vessel occlusion acute ischemic stroke.
- Collateral scoring using single-phase and multiphase CTA (Tan, Maas, Calgary/Menon methods).
- CT perfusion (CTP) analysis using RAPID software to calculate the hypoperfusion intensity ratio.
Main Results:
- Multiphase CTA scoring demonstrated superior interrater agreement (κ = 0.813) compared to single-phase CTA.
- The hypoperfusion intensity ratio showed a significant correlation with multiphase CTA collateral scores (r = -0.55, P ≤ .001).
- A hypoperfusion intensity ratio threshold of >0.45 effectively predicted poor multiphase CTA collateral status (AUC = 0.86).
Conclusions:
- The hypoperfusion intensity ratio is a reliable, automated, and quantitative measure associated with CTA collateral status in large-vessel occlusion stroke.
- This CTP-derived ratio serves as a valuable alternative to subjective CTA collateral scoring in clinical practice and stroke trials.
Background And Purpose:
Collateral blood supply is a key determinant of outcome in large-vessel occlusion acute ischemic stroke. Single- and multiphase CTA collateral scoring systems have been described but are subjective and require training. We aimed to test whether the CTP-derived hypoperfusion intensity ratio is associated with CTA collateral status and whether a threshold hypoperfusion intensity ratio exists that predicts poor CTA collaterals.
Materials And Methods:
Imaging and clinical data of consecutive patients with large-vessel occlusion acute ischemic stroke were retrospectively reviewed. Single-phase CTA and multiphase CTA scoring were performed by 2 blinded neuroradiologists using the Tan, Maas, and Calgary/Menon methods. CTP was processed using RApid processing of PerfusIon and Diffusion software (RAPID). Hypoperfusion intensity ratio = ratio of brain volume with time-to-maximum >10 seconds over time-to-maximum >6-second volume. Correlation between the hypoperfusion intensity ratio and CTA collateral scores was calculated using the Pearson correlation. The optimal threshold of the hypoperfusion intensity ratio for predicting poor collaterals was determined using receiver operating characteristic curve analysis.
Results:
Fifty-two patients with large-vessel occlusion acute ischemic stroke were included. Multiphase CTA collateral scoring showed better interrater agreement (κ = 0.813) than single-phase CTA (Tan, κ = 0.587; Maas, κ = 0.273). The hypoperfusion intensity ratio correlated with CTA collateral scores (multiphase CTA: r = -0.55; 95% CI, -0.67 to -0.40; P ≤ .001). The optimal threshold for predicting poor multiphase CTA collateral status was a hypoperfusion intensity ratio of >0.45 (sensitivity = 78%; specificity = 76%; area under the curve = 0.86). Patients with high hypoperfusion intensity ratio/poor collateral status had lower ASPECTS/larger infarcts, higher NIHSS scores, and larger hypoperfused volumes.
Conclusions:
The hypoperfusion intensity ratio is associated with CTA collateral status in patients with large-vessel occlusion acute ischemic stroke. The hypoperfusion intensity ratio is an automated and quantitative alternative to CTA collateral scoring methods for both clinical and future stroke trial settings.
