Short- and Long-Term MRI Assessed Hemodynamic Changes in Pediatric Moyamoya Patients After Revascularization

Abstract

Background: Cerebrovascular reserve (CVR) reflects the capacity of cerebral blood flow (CBF) to change following a vasodilation challenge. Decreased CVR is associated with a higher stroke risk in patients with cerebrovascular diseases. While revascularization can improve CVR and reduce this risk in adult patients with vasculopathy such as those with Moyamoya disease, its impact on hemodynamics in pediatric patients remains to be elucidated. Arterial spin labeling (ASL) is a quantitative MRI technique that can measure CBF, CVR, and arterial transit time (ATT) non-invasively.

Purpose: To investigate the short- and long-term changes in hemodynamics after bypass surgeries in patients with Moyamoya disease.

Study type: Longitudinal.

Population: Forty-six patients (11 months-18 years, 28 females) with Moyamoya disease.

Field strength/sequence: 3-T, single- and multi-delay ASL, T1-weighted, T2-FLAIR, 3D MRA.

Assessment: Imaging was performed 2 weeks before and 1 week and 6 months after surgical intervention. Acetazolamide was employed to induce vasodilation during the imaging procedure. CBF and ATT were measured by fitting the ASL data to the general kinetic model. CVR was computed as the percentage change in CBF. The mean CBF, ATT, and CVR values were measured in the regions affected by vasculopathy.

Statistical tests: Pre- and post-revascularization CVR, CBF, and ATT were compared for different regions of the brain. P-values <0.05 were considered statistically significant.

Results: ASL-derived CBF in flow territories affected by vasculopathy significantly increased after bypass by 41 ± 31% within a week. At 6 months, CBF significantly increased by 51 ± 34%, CVR increased by 68 ± 33%, and ATT was significantly reduced by 6.6 ± 2.9%.

Data conclusion: There may be short- and long-term improvement in the hemodynamic parameters of pediatric Moyamoya patients after bypass surgery.

Evidence level: 4 TECHNICAL EFFICACY: Stage 2.

Keywords: arterial spin labeling; arterial transit time; cerebral blood flow; cerebrovascular reserve; pediatrics.