Changes Of Signal Intensities Across Intracranial Arterial Stenosis On Magnetic Resonance Angiography Are Associated With Ipsilateral Cerebral Perfusion

Background: Intracranial arterial stenosis (ICAS) is a predominant cause of ischemic stroke in Asia. Changes of the signal intensities across ICAS lesions on time-of-flight magnetic resonance angiography (MRA) have been indicated to partially reflect the hemodynamic significance of the lesions, which we aimed to verify by correlating with cerebral perfusion features provided by CT perfusion imaging. Methods: Ischemic stroke or transient ischemic attack patients with unilateral symptomatic stenosis (≥50%) of intracranial internal carotid artery or middle cerebral artery were included in this study. Change of signal intensities across an ICAS lesion on time-of-flight MRA was calculated by the distal and proximal signal intensity ratio (SIR). Cerebral blood volume (CBV), cerebral blood flow (CBF), and mean transit time (MTT) within the middle cerebral artery territory of ipsilateral and contralateral hemispheres were evaluated on the CT perfusion images at the basal ganglia level. Relative CBV, CBF and MTT were defined as the ratios of the parameters obtained from ipsilateral and contralateral hemispheres. The relationships between SIR and CT perfusion parameters were analyzed. Results: Fifty subjects (74% male, mean age 62.84) were recruited. Overall, mean SIR was 0.77 ± 0.17. SIR of ICAS significantly, linearly and negatively correlated with ipsilateral CBV (r = -0.335, P = 0.017), CBF (r = -0.312, P = 0.028), and MTT (r = -0.301, P = 0.034), and relative MTT (r = -0.443, P = 0.001). Conclusions: Changes of the signal intensities across ICAS lesions on time-of-flight MRA may be a simple marker to reflect cerebral perfusion changes in patients with symptomatic ICAS.