Intracranial vascular feature changes in time of flight MR angiography in patients undergoing carotid revascularization surgery

Abstract

Purpose: To characterize the intracranial vascular features extracted from time of flight (TOF) images and their changes from baseline to follow-up in patients undergoing carotid revascularization, using arterial spin labeling (ASL) cerebral blood flow (CBF) measurement as a reference. Methods:In this retrospective study, brain TOF and ASL images of 99 subjects, acquired before, within 48 h, and/or 6 months after, carotid revascularization surgery were analyzed. TOF images were analyzed using a custom software (iCafe) to quantify intracranial vascular features, including total vessel length, total vessel volume, and number of branches. Mean whole-brain CBF was calculated from ASL images. ASL scans showing low ASL signal in the entire flow territory of an internal carotid artery (ICA), which may be caused by labeling failure, were excluded. Changes and correlations between time points were analyzed separately for TOF intracranial vascular features and ASL CBF.Results: Similar to ASL CBF, TOF vascular features (i.e. total vessel length, total vessel volume and number of branches) increased dramatically from baseline to post-surgery, then returned to a level slightly higher than the baseline in long-term follow-up (All P < 0.05). Correlation between time points was observed for all three TOF vascular features but not for ASL CBF. Conclusion:Intracranial vascular features, including total vessel length, total vessel volume and number of branches, extracted from TOF images are useful in detecting brain blood flow changes induced by carotid revascularization surgery.

Associations of intracranial artery length and branch number on non-contrast enhanced MRA with cognitive impairment in individuals with carotid atherosclerosis

“…The association on PC CBF and ASL CBF are in line with findings from previous cognition-related studies that also used PC or ASL MRI to measure brain blood flow 4 , 24 , 25 . Given the established correlation between intracranial vasculature features on TOF or SNAP and ASL or PC 12 , 13 , the association between TOF or SNAP intracranial artery length/number of branches and MoCA scores can be largely explained by the inherent sensitivity of TOF and SNAP sequences to blood flow. Importantly, although the TOF and SNAP sequences were not originally designed to measure brain blood flow, their associations with MoCA are not smaller than ASL CBF and PC CBF (Table 2 ).…”

“…Recently, features of cerebral vasculature, such as artery length and number of branches, obtained from brain non-contrast enhanced magnetic resonance angiography (NCE-MRA) imaging, such as time of flight (TOF) 10 and simultaneous non-contrast angiography and intraplaque hemorrhage (SNAP) 11 , have been proposed as potentially useful indicators of brain blood flow 12 , 13 . This is mainly due to the fact that artery visibility on NCE-MRA, and thus the derived relevant intracranial vascular features, are affected by blood flow.…”