Hypercapnic BOLD MRI compared to H215O PET/CT for the hemodynamic evaluation of patients with Moyamoya Disease

Abstract

Background and purpose: Patients with Moyamoya Disease (MMD) need hemodynamic evaluation of vascular territories at risk of stroke. Today's investigative standards include H215O PET/CT with pharmacological challenges with acetazolamide (ACZ). Recent developments suggest that CO2-triggered blood‑oxygen-level-dependent (BOLD) functional MRI might provide comparable results to current standard methods for evaluation of territorial hemodynamics, while being a more widely available and easily implementable method. This study examines results of a newly developed quantifiable analysis algorithm for CO2-triggered BOLD MRI in Moyamoya patients and correlates the results with H215O PET/CT with ACZ challenge to assess comparability between both modalities. Methods: CO2-triggered BOLD MRI was performed and compared to H215O PET/CT with ACZ challenge in patients with angiographically proven MMD. Images of both modalities were analyzed retrospectively in a blinded, standardized fashion by visual inspection, as well as with a semi-quantitative analysis using stimuli-induced approximated regional perfusion-weighted data and BOLD-signal changes with reference to cerebellum. Results: 20 consecutive patients fulfilled the inclusion criteria, a total of 160 vascular territories were analyzed retrospectively. Visual analysis (4-step visual rating system) of standardized, color-coded cerebrovascular reserve/reactivity maps showed a very strong correlation (Spearman's rho = 0.9, P < 0.001) between both modalities. Likewise, comparison of approximated regional perfusion changes across vascular territories (normalized to cerebellar change) reveal a highly significant correlation between both methods (Pearson's r = 0.71, P < 0.001). Conclusions: The present analysis indicates that CO2-triggered BOLD MRI is a very promising tool for the hemodynamic evaluation of MMD patients with results comparable to those seen in H215O PET/CT with ACZ challenge. It therefore holds future potential in becoming a routine examination in the pre- and postoperative evaluation of MMD patients after further prospective evaluation. Keywords: Moyamoya, PET/CT, Cerebrovascular reserve, BOLD MRI