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Updated: Sep 20, 2026
A Fibrin-Enriched and tPA-Sensitive Photothrombotic Stroke Model
Published on: June 4, 2021
Perfusion thresholds in acute stroke thrombolysis
K Butcher1, M Parsons, T Baird
1Department of Neurology, Royal Melbourne Hospital, Parkville, Victoria 3050, Australia. Kenneth.butcher@mh.org.au
Background And Purpose:
Perfusion-weighted MRI has been shown to be useful in the early identification of cerebral tissue at risk of infarction during acute ischemia. Identification of threshold perfusion measures that predict infarction may assist in the selection of patients for thrombolysis.
Methods:
Mean transit time (MTT), regional cerebral blood flow (rCBF), and regional cerebral blood volume (rCBV) maps were generated in 35 acute stroke patients (17 treated with tissue plasminogen activator and 18 control patients) imaged within 6 hours from symptom onset. Day 90 outcome infarcts (T2-weighted MRI) were superimposed on acute MTT, rCBF, and rCBV maps. Perfusion-weighted MRI measures were then calculated for 2 regions: infarcted and salvaged tissue.
Results:
MTT was prolonged by 22% in infarcted regions relative to salvaged tissue (P<0.001). rCBF was 10% lower in infarcted tissue than in salvaged regions (P<0.01). rCBV did not differ significantly between infarcted and salvaged regions. When reperfusion occurred, tissue with more severely prolonged MTT was salvaged from infarction relative to patients with persistent hypoperfusion (P<0.05). In contrast, rCBF in salvaged regions did not differ between patients with and without reperfusion. In reperfused patients, an inverse correlation (R=0.93, P<0.001) was found between time of initial MRI scan and MTT delay in salvaged tissue.
Conclusions:
Both increases in MTT and decreases in rCBF predict infarction. Differences in MTT also predict salvage in more severely hypoperfused tissue after reperfusion, suggesting that it is the most clinically useful quantitative perfusion measure. Perfusion thresholds for infarction need to be assessed in the context of symptom duration.
Insights
Mean transit time (MTT) and regional cerebral blood flow (rCBF) increases/decreases predict stroke infarction. MTT is the most useful measure for predicting tissue salvage after reperfusion in acute ischemic stroke patients.
Area of Science:
- Neurology
- Radiology
- Medical Imaging
Background:
- Perfusion-weighted MRI aids in early identification of at-risk cerebral tissue during acute ischemia.
- Identifying perfusion thresholds can help select acute stroke patients for thrombolysis therapy.
Purpose of the Study:
- To evaluate the predictive value of perfusion-weighted MRI parameters for cerebral infarction and tissue salvage.
- To determine the most clinically useful quantitative perfusion measure in acute ischemic stroke.
Main Methods:
- Generated Mean Transit Time (MTT), regional Cerebral Blood Flow (rCBF), and regional Cerebral Blood Volume (rCBV) maps in 35 acute stroke patients within 6 hours of symptom onset.
- Compared perfusion measures between infarcted and salvaged tissue at 90 days post-stroke.
- Analyzed the impact of reperfusion on tissue salvage in relation to MTT and rCBF.
Main Results:
- Prolonged MTT (22%) and reduced rCBF (10%) were significantly associated with infarcted tissue.
- rCBV did not significantly differ between infarcted and salvaged regions.
- More severely prolonged MTT predicted tissue salvage after reperfusion, while rCBF did not show this difference.
Conclusions:
- Both increased MTT and decreased rCBF are predictive of infarction in acute stroke.
- MTT is the most clinically useful perfusion measure for predicting salvage in hypoperfused tissue following reperfusion.
- Perfusion thresholds for infarction prediction require consideration of symptom duration.
