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Updated: May 12, 2026
A Magnetic Resonance Imaging Protocol for Stroke Onset Time Estimation in Permanent Cerebral Ischemia
Published on: September 16, 2017
Comparison of 10 TTP and Tmax estimation techniques for MR perfusion-diffusion mismatch quantification in acute
N D Forkert1, P Kaesemann, A Treszl
1Departments of Computational Neuroscience.
Background And Purpose:
The mismatch between lesions identified in perfusion- and diffusion-weighted MR imaging is typically used to identify tissue at risk of infarction in acute stroke. The purpose of this study was to analyze the variability of mismatch volumes resulting from different time-to-peak or time-to-maximum estimation techniques used for hypoperfused tissue definition.
Materials And Methods:
Data of 50 patients with middle cerebral artery stroke and intracranial vessel occlusion imaged within 6 hours of symptom onset were analyzed. Therefore, 10 different TTP/Tmax techniques and delay thresholds between +2 and +12 seconds were used for calculation of perfusion lesions. Diffusion lesions were semiautomatically segmented and used for mismatch quantification after registration.
Results:
Mean volumetric differences up to 40 and 100 mL in individual patients were found between the mismatch volumes calculated by the 10 TTP/Tmax estimation techniques for typically used delay thresholds. The application of typical criteria for the identification of patients with a clinically relevant mismatch volume resulted in different mismatch classifications in ≤24% of all cases, depending on the TTP/Tmax estimation method used.
Conclusions:
High variations of tissue-at-risk volumes have to be expected when using different TTP/Tmax estimation techniques. An adaption of different techniques by using correction formulas may enable more comparable study results until a standard has been established by agreement.
Insights
Different time-to-peak (TTP) or time-to-maximum (Tmax) methods significantly alter acute stroke mismatch volumes. This variability impacts patient classification, highlighting the need for standardized techniques in stroke imaging analysis.
Area of Science:
- Neuroradiology
- Acute Stroke Imaging
- Cerebrovascular Disease
Background:
- Perfusion and diffusion MRI mismatch identifies tissue at risk of infarction in acute stroke.
- Variability in mismatch volume estimation can affect clinical decision-making.
Purpose of the Study:
- To analyze the variability of mismatch volumes derived from different time-to-peak (TTP) or time-to-maximum (Tmax) estimation techniques.
- To assess the impact of these variations on the classification of patients with acute stroke.
Main Methods:
- Analysis of 50 middle cerebral artery stroke patients imaged within 6 hours of symptom onset.
- Utilized 10 distinct TTP/Tmax techniques with varying delay thresholds (+2 to +12 seconds) for perfusion lesion calculation.
- Semiautomatically segmented diffusion lesions and registered them for mismatch quantification.
Main Results:
- Observed mean volumetric differences up to 40-100 mL between mismatch volumes calculated by different TTP/Tmax methods.
- Clinically relevant mismatch classification varied in up to 24% of cases depending on the TTP/Tmax estimation technique used.
- Significant variability in tissue-at-risk volume estimation was demonstrated.
Conclusions:
- High variations in tissue-at-risk volumes are expected with different TTP/Tmax estimation techniques.
- Standardization or correction formulas are needed for comparable study results in acute stroke assessment.
- Addressing methodological variability is crucial for reliable clinical interpretation of perfusion-diffusion mismatch.
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