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Updated: Mar 20, 2026
A Magnetic Resonance Imaging Protocol for Stroke Onset Time Estimation in Permanent Cerebral Ischemia
Published on: September 16, 2017
A novel method to assess pial collateralization from stroke perfusion MRI: subdividing Tmax into anatomical
Arne Potreck1, Fatih Seker2, Angelika Hoffmann2
1Department of Neuroradiology, Heidelberg University Hospital, INF 400, 69120, Heidelberg, Germany. arne.potreck@med.uni-heidelberg.de.
Objectives:
To develop and validate a quantitative and observer-independent method to evaluate pial collateral circulation by DSC-perfusion MRI and test whether this novel method delivers diagnostic information which is redundant to or independent from conventional penumbra imaging by the mismatch approach.
Methods:
We retrospectively identified 47 patients with M1 occlusion who underwent MR diffusion/perfusion imaging and mechanical thrombectomy at our facility. By automated registration and segmentation, Tmax delays were attributed specifically to the pial, cortical and parenchymal compartments. The resulting pial volumes at delay were defined as the pial Tmax map-assessed collateral score (TMACS) and correlated with gold standard digital subtraction angiography (DSA). Mismatch ratio was assessed by conventional penumbra defining MRI criteria.
Results:
Strong correlation was found between TMACS and angiographically assessed collateral score (Pearson ρ = -0.74, p < 0.001). In multiple logistic regression, both good collaterals according to TMACS [OR 4.3 (1.1-19, p = 0.04)] and mismatch ratio ≥ 3.5 [OR 12.3 (1.88-249, p = 0.03)] were independent predictors of favourable clinical outcome.
Conclusions:
Perfusion delay in the pial compartment, as evaluated by TMACS, closely reflects the extent of pial collaterals in gold-standard DSA. TMACS and mismatch ratio were found to be complementary predictors of a favourable clinical outcome, each adding independent predictive information.
Key Points:
• MRI-DSC perfusion delay specific in the pial compartment reflects leptomeningeal collateralization. • A novel quantitative- and observer-independent marker of collateral status (TMACS) is introduced. • Quantification of collateral status leads to an independent predictor of neurological outcome.
Insights
A new MRI method, the pial Tmax map-assessed collateral score (TMACS), accurately quantifies pial collateral circulation. TMACS and the mismatch ratio independently predict favorable clinical outcomes in stroke patients.
Area of Science:
- Neuroradiology
- Neuroimaging
- Cerebrovascular disease
Background:
- Assessing pial collateral circulation is crucial for stroke management.
- Conventional methods for evaluating collaterals can be subjective and time-consuming.
Purpose of the Study:
- To develop and validate a quantitative, observer-independent method using DSC-perfusion MRI to assess pial collateral circulation.
- To determine if this novel method provides information independent of conventional penumbra imaging (mismatch approach).
Main Methods:
- Retrospective analysis of 47 patients with M1 occlusion undergoing MR diffusion/perfusion imaging and mechanical thrombectomy.
- Automated registration and segmentation to attribute Tmax delays to pial, cortical, and parenchymal compartments.
- Calculation of the pial Tmax map-assessed collateral score (TMACS) and correlation with digital subtraction angiography (DSA).
Main Results:
- A strong correlation was observed between TMACS and DSA-assessed collateral scores (Pearson ρ = -0.74, p < 0.001).
- Both good collaterals by TMACS and a high mismatch ratio were independent predictors of favorable clinical outcome.
- TMACS provides quantitative, observer-independent assessment of collateral status.
Conclusions:
- The TMACS method accurately reflects pial collateral extent as validated by DSA.
- TMACS and mismatch ratio are complementary predictors of favorable clinical outcome, offering independent predictive information.
- This novel quantitative marker of collateral status is an independent predictor of neurological outcome.
