Effects of Cerebral Perfusion and Total Intracranial Blood Supply in Small Vessel Disease: A Comparative Study between Multidelay Arterial Spin-Labeling and 4D Phase-Contrast MR Imaging.

BACKGROUND AND PURPOSE: Chronic hypoperfusion is considered a central mechanism in cerebral small vessel disease (CSVD). However, the results of studies on CBF vary across the imaging method, with phase-contrast (PC)-MRI reflecting large vessel blood flow and arterial spin-labeling (ASL) capturing tissue perfusion. We aimed to investigate the relationship between CSVD and CBF as measured by these 2 methods.

MATERIALS AND

METHODS

Ninety-four subjects from community and neurology clinics were enrolled. Global CBF was measured using 4D flow by summing the blood flow in the bilateral internal carotid arteries and the basilar artery and then normalizing by brain volume and density (ntCBFPC). Mean CBF was measured in the whole brain using multidelay ASL (wbCBFASL). CSVD imaging markers, including WM hyperintensities (WMHs), lacunes, perivascular spaces (PVSs), and microbleeds, were assessed in each subject, and a CSVD summary score was calculated to reflect the overall CSVD burden. Free water (FW) and tissue fractional anisotropy (tFA) were used to evaluate the microstructural integrity of white matter. Cognitive performance was assessed using neuropsychological tests. Associations between the 2 CBF measures, all CSVD imaging markers, and cognition were assessed while controlling for potential confounding variables.

RESULTS

Lower ntCBFPC (OR, 0.933; 95% CI, 0.884-0.984; P = .01) and wbCBFASL (OR, 0.914; 95% CI, 0.842-0.992; P = .03) were associated with higher basal ganglia-PVS scores. Lower ntCBFPC (OR, 0.798; 95% CI, 0.683-0.932; P = .004) and wbCBFASL (OR, 0.767; 95% CI, 0.636-0.926; P = .006) were associated with the presence of lacunes. Only wbCBFASL correlated with WM injury: higher periventricular WMH Fazekas score (OR, 0.868; 95% CI, 0.791-0.951; P = .003), larger WMH volume (β, -0.252; P = .02), higher FW (β, -0.314; P = .001), and lower tFA (β, 0.254; P = .02). No significant associations existed between ntCBFPC and WMH or diffusion imaging markers. Only ntCBFPC was positively associated with MMSE (β, 0.210; P = .04).

CONCLUSIONS

CBF measured by ASL demonstrates stronger CSVD associations than those derived from PC-MRI, suggesting that microcirculation impairment, rather than global blood flow, contributes more significantly to CSVD.