Related Experiment Video
Updated: Jan 10, 2026
Optimized Management of Endovascular Treatment for Acute Ischemic Stroke
Published on: January 18, 2018
Improved outcome prediction in large vessel occlusion stroke: A comparison of Tmax-based hypoperfusion ratios HIR10/4
Jeewon Chon1, Ashley Treanor1, Andrew C Pickles1
1Stritch School of Medicine, Loyola University Chicago, Maywood, IL, USA.
Insights
The hypoperfusion intensity ratio (HIR) using time-to-maximum (Tmax) >4s (HIR10/4) shows prognostic value in endovascular thrombectomy for LVO strokes. HIR10/4 may be a better biomarker than HIR10/6 for predicting outcomes.
Area of Science:
- Neuroimaging
- Stroke Medicine
- Radiology
Background:
- The hypoperfusion intensity ratio (HIR) from CT perfusion (CTP) assesses collateral flow quality in stroke.
- Optimal HIR formulation for predicting outcomes after endovascular thrombectomy (EVT) is not established.
Purpose of the Study:
- To compare the prognostic performance of HIR10/6 (Tmax >10s / >6s) versus HIR10/4 (Tmax >10s / >4s).
- To evaluate these HIR metrics in patients with large-vessel occlusion (LVO) stroke undergoing EVT.
Main Methods:
- Retrospective analysis of 280 LVO stroke patients treated with EVT (2015-2024).
- CTP data processed using RAPID software.
- Outcomes assessed: modified Rankin Scale (mRS) and NIHSS; secondary: hemorrhagic transformation. Regression models and ROC curves used for analysis.
Main Results:
- HIR10/4 demonstrated significant associations with worse mRS at discharge and 90 days, and higher NIHSS.
- Each 0.1-unit increase in HIR10/4 correlated with higher odds of poor outcomes.
- HIR10/6 showed weaker associations and was not significant for NIHSS; neither metric effectively discriminated hemorrhagic transformation.
Conclusions:
- Including mildly hypoperfused tissue (Tmax >4s) may improve HIR's physiologic sensitivity.
- HIR10/4 shows potential as a prognostic biomarker in EVT for LVO strokes.
- Prospective validation is required; standalone discriminative ability for binary outcomes is limited.
Background:
The hypoperfusion intensity ratio (HIR), derived from CT perfusion (CTP), reflects collateral flow quality, but its optimal formulation remains unsettled.
Objective:
To compare the prognostic utility of conventional HIR10/6 (time-to-maximum [Tmax] >10s / >6 s) with an alternative HIR10/4 (Tmax >10s / >4 s) in patients undergoing endovascular thrombectomy (EVT).
Methods:
We retrospectively analyzed consecutive large-vessel occlusion (LVO) strokes treated with EVT at our quaternary academic medical center (2015-2024). CTP was processed using RAPID software. Primary outcomes were modified Rankin Scale (mRS) at discharge and at 90 days. Secondary outcomes included National Institutes of Health Stroke Scale (NIHSS) at discharge and hemorrhagic transformation on follow-up imaging. Ordinal and linear regression models were adjusted for age, sex, vascular risk factors, intravenous thrombolysis, presentation window, and transfer status. Receiver operating characteristic (ROC) curves assessed discriminative performance.
Results:
Among 280 patients (mean age 70 ±15 years; 49 % male), mean HIR10/6 was 0.418 and HIR10/4 was 0.241. Each 0.1-unit increase in HIR10/4 translated to 31 % higher odds of worse mRS at discharge (adjusted odds ratio [aOR] 1.31, 95 % CI 1.12-1.54; p=0.001), 24 % higher odds of worse mRS at 90 days (aOR 1.24, 95 % CI 1.04-1.48; p=0.016), and higher discharge NIHSS (β=0.88, 95 % CI 0.05-1.71; p=0.039). HIR10/6 showed weaker associations and was not significant for discharge NIHSS. Neither HIR metric demonstrated meaningful discrimination for hemorrhagic transformation or dichotomized outcomes (area under the curve [AUC] 0.50-0.52).
Conclusions:
Incorporating mildly delayed tissue (Tmax >4 s) may enhance the physiologic sensitivity of HIR. HIR10/4 may be a potential prognostic biomarker; however, prospective validation is needed, and its standalone ability to discriminate binary outcomes remains limited.
