Morphology of perivascular spaces and enclosed blood vessels in young to middle-aged healthy adults at 7T: Dependences on age, brain region, and breathing gas

Abstract

Perivascular spaces (PVSs) are fluid-filled spaces surrounding penetrating blood vessels in the brain and are an integral pathway of the glymphatic system. A PVS and the enclosed blood vessel are commonly visualized as a single vessel-like complex (denoted as PVSV) in high-resolution MRI images. Quantitative characterization of the PVSV morphology in MRI images in healthy subjects may serve as a reference for detecting disease related PVS and/or blood vessel alterations in patients with brain diseases. To this end, we evaluated the age dependences, spatial heterogeneities, and dynamic properties of PVSV morphological features in 45 healthy subjects (21–55 years old), using an ultra-high-resolution three-dimensional transverse relaxation time weighted MRI sequence (0.41 × 0.41 × 0.4 mm 3 ) at 7T. Quantitative PVSV parameters, including apparent diameter, count, volume fraction (VF), and relative contrast to noise ratio (rCNR) were calculated in the white matter and subcortical structures. Dynamic changes were induced by carbogen breathing which are known to induce vasodilation and increase the blood oxygenation level in the brain. PVSV count and VF significantly increased with age in basal ganglia (BG), so did rCNR in BG, midbrain, and white matter (WM). Apparent PVSV diameter also showed a positive association with age in the three brain regions, although it did not reach statistical significance. The PVSV VF and count showed large inter-subject variations, with coefficients of variation ranging from 0.17 to 0.74 after regressing out age and gender effects. Both apparent diameter and VF exhibited significant spatial heterogeneity, which cannot be explained solely by radio-frequency field inhomogeneities. Carbogen breathing significantly increased VF in BG and WM, and rCNR in thalamus, BG, and WM compared to air breathing. Our results are consistent with gradual dilation of PVSs with age in healthy adults. The PVSV morphology exhibited spatial heterogeneity and large inter-subject variations and changed during carbogen breathing compared to air breathing.

Global and Regional Changes in Perivascular Space in Idiopathic and Familial Parkinson's Disease

“…In addition, we included regional analyses in the centrum semiovale and other cortical and subcortical white matter using a new approach developed by Sepehrband and colleagues 27 . Similar to our findings comparing FPD to NMC, studies in dementia and in aging have also reported increased global PVS in the centrum semiovale and other white matter regions compared to HCs 9,14,55,56 . However, in these studies, the relationship between increased PVS and cognitive decline remains unclear 17,18 …”

Perioperative Brain Edema in Meningioma Resection Procedures: Case Series and Experience of a Single Center

“…Through this space there is a perivascular channel from parenchymal arteries to the ones of the subarachnoid space. This discrepancy between the two zones, in other words, the subpial/pial- perivascular and subarachnoid-perivascular is more obvious in the basal cisterns [16].…”

Effects of motion and retrospective motion correction on the visualization and quantification of perivascular spaces in ultrahigh resolution T2‐weighted images at 7T

“…Physiological changes in both PVS and blood vessels can affect the apparent PVS signals. 22 Therefore, in this paper, we will refer to the combined structure of PVSs and enclosed blood vessels as PVSVs. The number of MRI-visible PVSVs increases with age.…”

“…The PVS and enclosed blood vessels often cannot be resolved in the MRI images due to limited spatial resolution. Physiological changes in both PVS and blood vessels can affect the apparent PVS signals 22 . Therefore, in this paper, we will refer to the combined structure of PVSs and enclosed blood vessels as PVSVs.…”