Arterial spin labeling versus bolus-tracking perfusion in hyperacute stroke

Area of Science:

• Neurology
• Radiology
• Medical Imaging

Background:

• Arterial spin labeling (ASL) is a contrast-free perfusion MRI technique.
• ASL may be more practical for hyperacute stroke than other perfusion imaging methods.
• Determining an ASL threshold for the ischemic penumbra is crucial.

Purpose of the Study:

• To establish a threshold for ASL-cerebral blood flow (CBF) to identify the ischemic penumbra in acute stroke.
• To compare ASL-based penumbra detection with established methods like PWI and CTP.

Main Methods:

• 58 acute ischemic stroke patients underwent MRI (ASL, DWI, PWI) and CTP within 6 hours of symptom onset.
• Repeat MRI at 24 hours was used to assess reperfusion status.
• A 40% ASL-CBF threshold was determined using ROC analysis and volumetric analysis in non-reperfused patients.

Main Results:

• A 40% ASL-CBF threshold demonstrated high accuracy (AUC 0.76) in detecting the acute penumbra compared to 24-hour DWI.
• This threshold also showed strong agreement with PWI (AUC 0.79) and CTP (AUC 0.77) penumbra thresholds.
• An ASL-CBF 40% mismatch ratio of 1.8:1 showed good sensitivity (0.81) and specificity (0.71).

Conclusions:

• ASL-DWI mismatch shows significant potential for identifying salvageable brain tissue in hyperacute stroke.
• ASL offers a promising, contrast-free alternative for perfusion assessment in stroke imaging.