Background: The aim of this study was to evaluate whether arterial spin labeling (ASL) perfusion magnetic resonance imaging (MRI) can reliably quantify perfusion deficit as compared to dynamic susceptibility contrast (DSC) perfusion MRI.
Methods: Thirty-nine patients with acute ischemic stroke in the anterior circulation territory were recruited. All underwent ASL and DSC MRI perfusion scans within 30 hours after stroke onset and 31 patients underwent follow-up MRI scans. ASL cerebral blood flow (CBF) and DSC time to maximum (T(max)) maps were used to calculate the perfusion defects. The ASL CBF lesion volume was compared to the DSC Tmax lesion volume by Pearson's correlation coefficient and likewise the ASL CBF and DSC T(max) lesion volumes were compared to the final infarct sizes respectively. A repeated measures analysis of variance and least significant difference post hoc test was used to compare the mean lesion volumes among ASL CBF, DSC T(max) >4-6 s and final infarct.
Results: Mean patient age was 72.6 years. The average time from stroke onset to MRI was 13.9 hours. The ASL lesion volume showed significant correlation with the DSC lesion volume for T(max) >4, 5 and 6 s (r = 0.81, 0.82 and 0.80; p<0.001). However, the mean lesion volume of ASL (50.1 ml) was significantly larger than those for T(max) >5 s (29.2 ml, p<0.01) and T(max) >6 s (21.8 ml, p<0.001), while the mean lesion volumes for T(max) >5 or 6 s were close to mean final infarct size.
Conclusion: Quantitative measurement of ASL perfusion is well correlated with DSC perfusion. However, ASL perfusion may overestimate the perfusion defects and therefore further refinement of the true penumbra threshold and improved ASL technique are necessary before applying ASL in therapeutic trials.