Studying blood flow in small vessels using non-invasive imaging

Published on May 19, 2022

Imagine you’re a detective, investigating a mysterious crime scene. You need to gather all the clues to solve the case. In this pilot study, scientists used a cool technique called arterial spin labeling magnetic resonance imaging (ASL MRI) to investigate how blood flows in the small vessels of patients with cerebral small vessel disease (CSVD). They measured cerebral blood flow (CBF), arterial transit time (ATT), and effective T1-relaxation time (T1eff) to understand a new way of assessing clearance of waste products around these vessels. Using the brain as their playing field, they classified the severity of CSVD by evaluating white matter hyperintensities (WMHs), lacunes, enlarged perivascular spaces (EPVSs), and cerebral microbleeds (CMBs). The results showed that CBF decreased and ATT increased as CSVD severity worsened. Interestingly, impaired clearance was indicated by longer T1eff values in both gray matter and white matter of CSVD patients compared to healthy elderly individuals. This study builds upon previous work on CSVD-related reduced blood flow by revealing delayed arrival times of arterial blood and slower waste clearance rates. If you want to dive deeper into the exciting world of microvascular impairment in CSVD, put on your lab coat and click on the link below to read the full article!

In this pilot study, we investigated microvascular impairment in patients with cerebral small vessel disease (CSVD) using non-invasive arterial spin labeling (ASL) magnetic resonance imaging (MRI). This method enabled us to measure the perfusion parameters, cerebral blood flow (CBF), and arterial transit time (ATT), and the effective T1-relaxation time (T1eff) to research a novel approach of assessing perivascular clearance. CSVD severity was characterized using the Standards for Reporting Vascular Changes on Neuroimaging (STRIVE) and included a rating of white matter hyperintensities (WMHs), lacunes, enlarged perivascular spaces (EPVSs), and cerebral microbleeds (CMBs). Here, we found that CBF decreases and ATT increases with increasing CSVD severity in patients, most prominent for a white matter (WM) region-of-interest, whereas this relation was almost equally driven by WMHs, lacunes, EPVSs, and CMBs. Additionally, we observed a longer mean T1eff of gray matter and WM in patients with CSVD compared to elderly controls, providing an indication of impaired clearance in patients. Mainly T1eff of WM was associated with CSVD burden, whereas lobar lacunes and CMBs contributed primary to this relation compared to EPVSs of the centrum semiovale. Our results complement previous findings of CSVD-related hypoperfusion by the observation of retarded arterial blood arrival times in brain tissue and by an increased T1eff as potential indication of impaired clearance rates using ASL.

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