Reliability and Sensitivity to Longitudinal CBF Changes in Steno-Occlusive Diseases: ASL Versus 123 I-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 T1 -weighted and spin-echo ASL.

ASSESSMENT: Multi-delay ASL and [123 I]-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 (ΔCBF) and their postlabeling delay (PLD) dependency with varied PLDs (in milliseconds) of 1000, 2333, and 3666 were examined.

STATISTICAL TESTS: Reliability and sensitivity to ΔCBF were examined using within-subject standard deviation (Sw) and intraclass correlation coefficients (ICCs). For statistical comparisons, standard deviation of longitudinal ΔCBF within the hemisphere contralateral to surgery, and the ratio between it and average ΔCBF 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 ΔCBF 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 ΔCBF. ASL test-retest reliability and sensitivity to ΔCBF were higher with a PLD of 2333.

LEVEL OF EVIDENCE: 1 TECHNICAL EFFICACY: Stage 2.