Reliability and Sensitivity to Longitudinal CBF Changes in Steno-Occlusive Diseases: ASL Versus 123I-IMP-SPECT

Background Noninvasive cerebral blood flow (CBF) monitoring using arterial spin labeling (ASL) magnetic resonance imaging is useful for managing large cerebral artery steno-occlusive diseases. However, knowledge about its measurement characteristics in comparison with reference standard perfusion imaging is limited. Purpose To evaluate perfusion in a longitudinal manner in patients with steno-occlusive disease using ASL and compare with single-photon emission computed tomography (SPECT). Study Type Prospective. Population Moyamoya (n = 10, eight females) and atherosclerotic diseases (n = 2, two males). Field Strength/Sequence 3.0 T; gradient-echo three-dimensional T-1-weighted and spin-echo ASL. Assessment Multi-delay ASL and [I-123]-iodoamphetamine SPECT CBF measurements were performed both before and within 9 days of anterior-circulation revascularization. Reliability and sensitivity to whole-brain voxel-wise CBF changes (Delta CBF) and their postlabeling delay (PLD) dependency with varied PLDs (in milliseconds) of 1000, 2333, and 3666 were examined. Statistical Tests Reliability and sensitivity to Delta CBF were examined using within-subject standard deviation (Sw) and intraclass correlation coefficients (ICCs). For statistical comparisons, standard deviation of longitudinal Delta CBF within the hemisphere contralateral to surgery, and the ratio between it and average Delta CBF within the ipsilateral regions of interest were subjected to paired t tests, respectively. P < 0.05 was considered statistically significant. Results ASL test-retest time interval was 31 +/- 18 days. Test-retest reliability was significantly lower for SPECT (0.16 +/- 0.02) than ASL (0.13 +/- 0.04). Sensitivity to postoperative changes was significantly higher for ASL (2.71 +/- 2.79) than SPECT (0.27 +/- 0.62). Test-retest reliability was significantly higher for a PLD of 2333 (0.13 +/- 0.04) than 3666 (0.19 +/- 0.05), and sensitivity to Delta CBF was significantly higher for PLDs of 1000 (2.53 +/- 2.50) and 2333 than 3666 (0.79 +/- 1.88). ICC maps also showed higher reliability for ASL than SPECT. Data Conclusion Higher test-retest reliability led to better ASL sensitivity than SPECT for postoperative Delta CBF. ASL test-retest reliability and sensitivity to Delta CBF were higher with a PLD of 2333. Level of Evidence 1 Technical Efficacy Stage 2

Automated summary

Noninvasive cerebral blood flow monitoring using ASL MRI is more reliable and sensitive than SPECT in evaluating perfusion changes in patients with steno-occlusive diseases. ASL test-retest reliability and sensitivity were higher with a postlabeling delay of 2333 milliseconds.