Abstract TP55: Comparison of Arterial Spin Labeling and Dynamic Susceptibility Contrast Perfusion for Quantitative Evaluation of Mismatch in Successfully Recanalized Acute Stroke Patients
Purpose: Arterial spin labeling (ASL) has gained attention in evaluation of acute stroke as an alternative perfusion method that does not require contrast. We evaluate the agreement of ASL and dynamic susceptibility contrast (DSC) mismatch classification using a quantitative method in successfully recanalized patients.
Methods: This retrospective study was performed using MR examinations acquired between 2010-2012. Inclusion criteria were: patients with acute stroke who underwent successful recanalization and acquisition of both ASL and DSC before and after revascularization. The volumes of DWI and hypoperfused (Tmax > 6 seconds) lesions were calculated on DSC using an automated software. The hypoperfusion volumes on ASL were calculated using a region of interest-based analysis. The ratios of volume of the hypoperfusion region to DWI lesion were calculated and used to classify the patients into 3 categories: 1) mismatch: ratio >2; 2) matched: 0.7 < ratio < 2; and 3) reperfused: ratio < 0.7. Intermodality agreement for mismatch categories was evaluated with Kappa test.
Results: Seventeen patients met the inclusion criteria, resulting in 34 pair of ASL-DSC for comparison. The mean ± SD of the volumes of the DWI lesions was 14.2± 8 ml and 18.2 ± 13 ml before and after revascularization respectively. ASL overestimated the hypoperfusion volume in both pre and post-treatment groups (p<0.01) in comparison to DSC-Tmax lesion volume. In pre-treatment group, ASL-DWI and DSC-DWI mismatch categories agreed in 15 of 17 cases (88%) with high agreement (k=0.82; 95% CI, 0.3 -0.87). In post-treatment group, ASL-DWI and DSC-DWI mismatch categories agreed in 11 of 17 cases (64%) with moderate agreement (k=0.46; 95% CI,0.25-0.82). Out of 6 discrepant cases, three reperfused patients on DSC were categorized matched on ASL and 3 matched cases on DSC were classified as mismatch on ASL.
Conclusion: ASL overestimates the DSC time to maximum lesion volume. There is only moderate agreement between ASL and DSC in mismatch classification of revascularized patients, suggestive of less sensitivity of ASL in detection of reperfusion. Improvement in ASL methods with varying degree post-labeling delay may be needed for evaluation of revascularized patients.
- © 2012 by American Heart Association, Inc.