Arterial spin labelling reveals prolonged arterial arrival time in idiopathic Parkinson's disease

Abstract

Idiopathic Parkinson's disease (IPD) is the second most common neurodegenerative disease, yet effective disease modifying treatments are still lacking. Neurodegeneration involves multiple interacting pathological pathways. The extent to which neurovascular mechanisms are involved is not well defined in IPD. We aimed to determine whether novel magnetic resonance imaging (MRI) techniques, including arterial spin labelling (ASL) quantification of cerebral perfusion, can reveal altered neurovascular status (NVS) in IPD.Fourteen participants with IPD (mean ± SD age 65.1 ± 5.9 years) and 14 age and cardiovascular risk factor matched control participants (mean ± SD age 64.6 ± 4.2 years) underwent a 3T MRI scan protocol. ASL images were collected before, during and after a 6 minute hypercapnic challenge. FLAIR images were used to determine white matter lesion score. Quantitative images of cerebral blood flow (CBF) and arterial arrival time (AAT) were calculated from the ASL data both at rest and during hypercapnia. Cerebrovascular reactivity (CVR) images were calculated, depicting the change in CBF and AAT relative to the change in end-tidal CO2.A significant (p = 0.005) increase in whole brain averaged baseline AAT was observed in IPD participants (mean ± SD age 1532 ± 138 ms) compared to controls (mean ± SD age 1335 ± 165 ms). Voxel-wise analysis revealed this to be widespread across the brain. However, there were no statistically significant differences in white matter lesion score, CBF, or CVR between patients and controls. Regional CBF, but not AAT, in the IPD group was found to correlate positively with Montreal cognitive assessment (MoCA) scores. These findings provide further evidence of alterations in NVS in IPD.

Retinotopic Changes in the Gray Matter Volume and Cerebral Blood Flow in the Primary Visual Cortex of Patients With Primary Open-Angle Glaucoma

“…[45][46][47] These findings suggest a common involvement of the neurovascular mechanism in neurodegenerative diseases of the CNS. Dysregulated cerebrovascular reactivity may lead to unstable oxygen supply to local neurons, and may actively participate in the acceleration of neurodegeneration in the brain of the patients.…”

Neuroimaging of Parkinson's disease: Expanding views

“…Al-Bachari et al (2014) examined neurovascular status in PD through ASL measures of arterial arrival time (AAT). Widespread regions of the brain showed prolongation of AAT.…”

Quantitative measurement of blood flow in paediatric brain tumours—a comparative study of dynamic susceptibility contrast and multi time-point arterial spin labelled MRI

“…13 A previous work in PBTs has used a more complex model, providing measures of pre-capillary and capillary arrival time. 8 We felt that the lower temporal resolution of our ASL data (370 ms compared with 200 ms in Ref.…”

“…Control and label images were subtracted and averaged to provide difference images at each timepoint. A single blood compartment model, 12 adapted for the Look–Locker readout, 13 was fit to the averaged images on a voxel-by-voxel basis, producing maps of CBF and AAT (without vascular crushing) and CBF with vascular crushing (CBF VC ) and AAT with vascular crushing (AAT VC ) (with vascular crushing). This model assumes that labelled water remains in the blood and that no labelled water leaves the voxel, an approach that has been shown to be reasonably accurate.…”