Collateral Mapping Predicts Lesion Growth and Penumbra in Acute Anterior Circulation Stroke

Overview

Collateral mapping using dynamic contrast-enhanced MR angiography can predict lesion expansion and penumbral extent in acute ischemic stroke due to anterior circulation large vessel occlusion. This imaging method provides a dynamic assessment of collateral circulation that correlates with infarct growth and functional outcomes.

Background

Recanalization treatments aim to salvage the ischemic penumbra to improve functional outcomes in acute ischemic stroke. Current penumbra estimation using Tmax > 6 s thresholds on perfusion imaging tends to overestimate salvageable brain tissue, potentially leading to suboptimal patient selection. Collateral circulation plays a crucial role in determining infarct growth and outcome, but existing collateral imaging techniques lack dynamic tissue status information. This study evaluates a novel collateral mapping technique derived from dynamic contrast-enhanced MR angiography to better predict lesion growth and penumbra.

Data Highlights

Key Findings

• Collateral maps generated from dynamic contrast-enhanced MR angiography provide a dynamic, phase-based assessment of collateral circulation in acute ischemic stroke.
• Better collateral perfusion grades correlate with slower infarct growth and larger penumbral areas, indicating more salvageable brain tissue.
• Lesion growth ratio ≥ 1.2 was used to define significant infarct expansion, reflecting penumbral extent.
• Traditional Tmax > 6 s perfusion imaging tends to overestimate penumbra volume, whereas collateral mapping offers improved regional estimation.
• Collateral status assessed by collateral maps is predictive of functional outcomes at 90 days post-stroke.

Clinical Implications

Collateral mapping can enhance patient selection for recanalization therapies by more accurately identifying salvageable brain tissue and forecasting lesion growth. This method may reduce the inclusion of patients unlikely to benefit from intervention due to minimal penumbra. Incorporating collateral mapping into acute stroke imaging protocols could improve prognostication and treatment decision-making.

Conclusion

Collateral mapping using dynamic contrast-enhanced MR angiography is a promising tool for predicting lesion expansion and penumbral area in acute anterior circulation ischemic stroke, potentially improving patient selection and outcomes in recanalization therapies.

References

1. HERMES Collaboration 2016 -- Endovascular thrombectomy after large-vessel ischaemic stroke
2. Wintermark et al. 2006 -- Perfusion-CT assessment of infarct core and penumbra
3. Heiss 2000 -- PET imaging of ischemic penumbra
4. Campbell et al. 2019 -- Optimal Tmax thresholds for penumbra delineation
5. Bivard et al. 2017 -- Variability in Tmax calculation across software
6. Olivot et al. 2014 -- Impact of software on perfusion imaging results
7. Liebeskind 2003 -- Collateral circulation and stroke outcome
8. Menon et al. 2015 -- Collateral status and infarct growth
9. Miteff et al. 2009 -- Collateral circulation and hemorrhagic transformation
10. Lansberg et al. 2014 -- Collateral circulation in thrombectomy outcomes
11. Kim et al. 2017 -- Limitations of current collateral imaging methods
12. Liu et al. 2018 -- Arterial transit artifact in collateral assessment
13. Lee et al. 2020 -- Collateral mapping methodology
14. Lee et al. 2021 -- Dynamic contrast-enhanced MR angiography in stroke