Superficial temporal artery-middle cerebral artery bypass signal intensity in time of flight magnetic resonance angiography as a marker of cerebral perfusion after revascularization procedure in moyamoya disease patients

The study was conducted to evaluate whether superficial temporal artery-middle cerebral artery (STA-MCA) bypass signal intensity has any correlation with cerebral perfusion on arterial spin labeling (ASL) perfusion in patients with Moyamoya disease (MMD), who underwent cerebral revascularization. Seventeen patients, who had STA-MCA bypass, were enrolled in this observational study and subjected to be followed up with MRI at three months post-operative interval. Region of interest (ROI) was placed in time of flight magnetic resonance angiography (TOF-MRA) images on STA-MCA bypass on the side where surgery was done. Signal intensity (SI) values obtained were normalized by converting them into ratio by taking signal intensity values of the common carotid artery just before its bifurcation as the denominator. The obtained STA-MCA bypass SI ratios were then compared with normalized cerebral blood flow (CBF) values obtained on ASL perfusion to look for correlation. Data analysis was done using SPSS software version 20.0 and GraphPad Prism 6. Spearman’s rank correlation coefficient was calculated between TOF-MRA and ASL MR perfusion parameters. A statistically significant positive correlation was found between STA-MCA bypass signal intensity with CBF of the frontal lobe (r = 0.532; P = 0.0280), CBF of the parietal lobe (r = 0.716; P = 0.001), and CBF of the temporal lobe (r=0.52; P = 0.033). However, there was no significant correlation between STA-signal intensity and CBF of basal ganglia (r = 0.128; P = 0.626).