Wall shear rates differ between the normal carotid, femoral, and brachial arteries: An in vivo MRI study

Purpose To investigate wall shear rates in vivo in the common carotid, brachial, and superficial femoral arteries using very high resolution magnetic resonance imaging (MRI) phase contrast measurements. Materials and Methods Mean, maximum, and minimum wall shear rate and an oscillatory shear index were measured for 20 volunteers, aged 23.3 ± 1.9 years, in the three arteries, using phase contrast imaging with 0.0625 mm2 resolution and three‐dimensional paraboloid fitting. Results The superficial femoral artery had the lowest mean (130.3 ± 13.1 second−1), maximum (735.8 ± 32.4 second−1), and minimum (–224.5 ± 17.0 second−1) wall shear rate, as well as the highest oscillatory shear index (0.21 ± 0.02). All values were significantly different (P < 0.05) from both the brachial artery and the common carotid artery values. The highest mean (333.3 ± 13.6 second−1) and minimum (117.9 ± 24.5 second−1) wall shear rates and the lowest oscillatory shear index (0 ± 0) were found in the common carotid artery. Conclusion It is possible to measure wall shear rate in vivo in different arteries using MRI with very high resolution. The findings exhibit the in vivo environment of wall shear rates and suggest a nonuniform distribution of wall shear rates throughout the arterial system. J. Magn. Reson. Imaging 2004;19:188–193. © 2004 Wiley‐Liss, Inc.