Comparison of arterial spin labeling and dynamic susceptibility contrast perfusion MRI in patients with acute stroke

Abstract

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.

Figure 1. ADC, ASL perfusion (CBF), DSC perfusion (T_max >5 s), and follow-up FLAIR imaging of the representative patients.

(A) A 60-year-old man underwent MRI at 8.8 hours after stroke onset. The ADC imaging showed an acute infarct in the left MCA territory. Larger perfusion defect areas were seen in the ASL map (arrow) and T_max map (arrowhead), indicating a mismatch. The follow-up FLAIR imaging showed a progressed infarct with hemorrhage. (B) A 77-year-old man underwent MRI at 8.2 hours after stroke onset. The ADC imaging showed an infarct in the right MCA territory. Although a large perfusion defect was observed in the ASL map (arrow), the Tmax map showed only a small defect (arrowhead), consistent with the ADC and follow-up FLAIR imaging.

Figure 2. ADC, ASL perfusion (CBF), DSC perfusion (T_max >5 s), and follow-up FLAIR imaging of the representative patients.

(A) A 76-year-old man underwent MRI at 5.0 hours after stroke onset. An acute infarct was noted in the right centrum semiovale in the ADC and follow-up FLAIR images. A perfusion defect was observed in the ASL map (arrow) but not in the T_max map. (B) A 60-year-old man underwent MRI at 22.6 hours after stroke onset. The ADC image showed an acute infarct in the left centrum semiovale with a corresponding perfusion defect in the ASL map (arrow), but not in the T_max map.

Figure 3. The mean lesion volumes of ADC, ASL CBF, DSC T_max(>4–6 s), and final infarct in 31 patients with follow-up image.

Bars indicate as mean±standard error. *: Statistically significant, p<0.05, by repeated measures ANOVA & LSD post hoc test.

Figure 4. ASL and DSC lesion volumes with correlation to the final infarct volumes.

Compared to DSC, ASL usually overestimated the perfusion deficits, especially in patients with small final infarcts.