Diffusivity Along the Perivascular Space is Decreased and Related to Hypoperfusion in Adult Moyamoya disease

Abstract

Abstract Background Moyamoya disease is a rare cerebrovascular disease causing progressive arterial stenosis and hemodynamic disturbance. Decreased arterial input and cerebral perfusion pressure in this disease may disrupt glymphatic system activity, the waste clearance system of the brain that uses arterial input as a driving force. Purpose To evaluate the glymphatic system function of adult patients with moyamoya disease using diffusivity along the perivascular space measured with diffusion tensor imaging (ALPS index). Materials and Methods In this secondary analysis of a prospective observational study from 2015 to 2021 (UMIN000027949), 45 patients and 33 age-sex matched controls were evaluated with multishell diffusion MRI, and 23 patients were also evaluated with 15O-gas positron emission tomography (PET). All patients were also evaluated with cognitive tests. The ALPS index of each hemisphere was calculated from single shell data, and freewater maps was calculated from multishell diffusion data using neurite orientation and density imaging analysis. The ALPS index of the patients was compared with controls, as well as hemispheric values of freewater paremeters, perfusion parameters measured with PET, and scores of cognitive tests. Results Compared to controls, patients (38.4 (13.2) year-old, 35 females) showed lower ALPS index in the left and the right hemispheres (1.94 (0.27) vs. 1.65 (0.25) and 1.94 (0.22) vs. 1.65 (0.19), P < .001). The left ALPS index correlated with parenchymal freewater (ρ =-0.47, P < .001), perfusion measured with PET (cerebral blood flow, ρ = 0.70, P < .001; mean transit time, ρ =-0.60, P = .003; and oxygen extraction fraction, ρ =-0.52, P = .003), and cognitive tests (trail making test part B that measures executive function; ρ=-0.37, P = .01). Conclusion Patients with moyamoya disease has decreased diffusivity along the perivascular space. The glymphatic system dysfunction may exist, correlate with the degree of hemodynamic disturbance, lead to increased parenchymal free water, and relate to cognitive dysfunction in adult patients with moyamoya disease.