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Assessment of Arterial Transit Time and Cerebrovascular Reactivity in Moyamoya Disease by Simultaneous PET/MRI
Kenji Takata1, Hirohiko Kimura1, Shota Ishida2
1Department of Radiology, Faculty of Medical Sciences, University of Fukui, Fukui 910-1193, Japan.
Abstract:
We investigated the relationship between MRI-arterial spin labeling (ASL) parameters and PET-cerebral blood flow (CBF)/cerebrovascular reactivity (CVR) simultaneously obtained by PET/MRI in Moyamoya disease. Twelve patients underwent 15O-water PET/MRI with the acetazolamide (ACZ) challenge test. PET-CBF and PET-CVR were measured using 15O-water PET. Pseudo-continuous ASL obtained the robust arterial transit time (ATT) and ASL-CBF estimation. ASL parameters were compared with PET-CBF and PET-CVR. Before ACZ loading, absolute and relative ASL-CBF were significantly correlated with absolute and relative PET-CBF (r = 0.44, p < 0.0001, and r = 0.55, p < 0.0001, respectively). After ACZ loading, absolute and relative ASL-CBF were significantly correlated with absolute and relative PET-CBF (r = 0.56, p < 0.001, and r = 0.75, p < 0.0001, respectively), and ΔASL-CBF was significantly correlated with ΔPET-CBF (r = 0.65, p < 0.0001). Baseline ASL-ATT had strong negative correlations with ΔPET-CBF and PET-CVR (r = -0.72, p < 0.0001, and r = -0.66, p < 0.0001, respectively). Baseline ASL-ATT of MCA territories with CVR <30% (1546 ± 79 ms) was significantly higher than that with CVR > 30% (898 ± 197 ms). ASL-ATT ratio of MCA territories with CVR < 30% (94.0 ± 10.5%) was significantly higher than that with CVR > 30% (81.4 ± 11.3%). ATT correction using multiple postlabeling delays increased the accuracy of ASL-CBF quantitation. Baseline ASL-ATT is a hemodynamic parameter and may represent an efficient alternative to PET-CVR.
Insights
Arterial spin labeling (ASL) magnetic resonance imaging (MRI) accurately estimates cerebral blood flow (CBF) and cerebrovascular reactivity (CVR) in Moyamoya disease. ASL arterial transit time (ATT) shows strong correlations with PET-derived CVR, suggesting it as a potential alternative for assessing hemodynamic status.
Area of Science:
- Neuroimaging
- Vascular Neurology
- Radiology
Background:
- Moyamoya disease is a rare cerebrovascular disorder characterized by progressive stenosis of the internal carotid arteries.
- Accurate assessment of cerebral blood flow (CBF) and cerebrovascular reactivity (CVR) is crucial for managing Moyamoya disease.
- Positron emission tomography (PET) is a gold standard for measuring CBF and CVR, but magnetic resonance imaging (MRI) with arterial spin labeling (ASL) offers a non-invasive alternative.
Purpose of the Study:
- To investigate the relationship between MRI-ASL parameters and simultaneously obtained PET-CBF/CVR in patients with Moyamoya disease.
- To evaluate the accuracy of ASL in quantifying CBF and assessing CVR compared to PET.
- To determine if ASL-derived arterial transit time (ATT) can serve as a surrogate marker for CVR.
Main Methods:
- Twelve patients with Moyamoya disease underwent simultaneous 15O-water PET/MRI.
- Acetazolamide (ACZ) challenge test was performed to assess CVR.
- PET-CBF and PET-CVR were measured using 15O-water PET; pseudo-continuous ASL was used for ASL-CBF and ATT estimation.
Main Results:
- ASL-CBF showed significant correlations with PET-CBF both before and after ACZ loading (r = 0.44-0.75, p < 0.0001).
- ΔASL-CBF correlated significantly with ΔPET-CBF after ACZ challenge (r = 0.65, p < 0.0001).
- Baseline ASL-ATT demonstrated strong negative correlations with ΔPET-CBF and PET-CVR (r = -0.66 to -0.72, p < 0.0001).
- Higher ASL-ATT was observed in MCA territories with CVR < 30% compared to those with CVR > 30%.
Conclusions:
- MRI-ASL provides accurate estimation of CBF and CVR in Moyamoya disease, comparable to PET.
- Baseline ASL-ATT is a significant hemodynamic parameter that strongly correlates with PET-CVR.
- ASL-ATT may serve as an efficient, non-invasive alternative to PET-CVR for assessing cerebrovascular hemodynamics in Moyamoya disease.
