Phase-contrast magnetic resonance imaging for the evaluation of wall shear stress in the common carotid artery of a spontaneously hypertensive rat model at 7 T: Location-specific change, regional distribution along the vascular circumference, and reproducibility analysis

Purpose: To measure wall shear stress (WSS) in the common carotid arteries (CCA) of a spontaneously hypertensive rat (SHR) model and a normotensive Wistar Kyoto rat (WKY) model by 2D phase-contrast magnetic resonance imaging (PC-MRI). Materials and methods: PC-MRI was performed on 7 SHR and 7 WKY at ages of 4 and 7 months at a 7 T scanner. Images in the middle CCA (CCA(mid)) and in the bifurcation of CCA (CCA(bifur)) were acquired. The WSS values for differentiating characteristics between two models were calculated. Further, its location-specific change, regional distribution along the CCA circumference, and the reproducibility were evaluated. Results: In the 4-month-old rats, SHR showed lower temporal averaged WSS (WSSavg) and peak systolic WSS (WSSs) in the CCAbifur in comparison with WKY (WSSavg: 0.95 +/- 0.18 vs. 1.30 +/- 0.36 N/m(2) (P < 0.01); WSSs: 1.68 +/- 0.70 vs. 3.22 +/- 2.49 N/m(2) (P < 0.05)). We observed the same trends in the 7-month-old rats. In the SHR model, the WSSavg was lower in the CCA(bifur) than in the CCA(mid). The regional distribution of WSSavg along the circumference of CCA showed lower values in WKY, particularly in posterior segments of CCA(bifur) The intra-observer, intra-scan and inter-scan reproducibility was acceptable and the disagreements were ranged from -0.05 to 0.06 N/m(2). Conclusion: This study evaluated WSS in SHR and WKY models by 2D PC-MRI. High reproducibility analyses further indicated the reliability of measurements of WSS in the CCA of SHR and WKY models using PC-MRI at 7 T. (C) 2016 Elsevier Inc. All rights reserved.