Combined readings of both raters for signal intensities of left middle cerebral artery, adjacent gray matter and calculated vessel-tissue contrast ratio for all subjects.

Vessel-tissue contrast ratio of the middle cerebral artery (MCA) were assessed in correlation to surrounding gray matter (GM) for 7 Tesla (T) magnetization prepared rapid acquisition gradient echo (MPRAGE) sequences, 7T time-of-flight (TOF) sequences and for 1.5T TOF sequences. Therefore, regions of interest (ROI) were defined in the largest diameter of the proximal left M1 segments and adjacent gray matter . The average diameter for the ROI of the vessel was 3–5 mm; the ROI for brain parenchyma amounted to approximately 1 cm.
standard error  = 0.012, 95% confidence interval [0.623 – 0.675].
standard error =  0.010, 95% confidence interval [0.639 – 0.681].
standard error =  0.008, 95% confidence interval [0.587 – 0.622].