Determination of wall shear rate in the human carotid artery by magnetic resonance techniques

Objectives: to measure wall shear mt cycle. Design: prospective, open study. Materials: eight healthy volunteers. Methods: wall shear rates were determined at the carotid bifurcation using magnetic resonance techniques with high resolution and individually adjusted velocity encoding for imaging and haemodynamic mapping. Wall shear stresses were calculated assuming a constant value of 4 centiPoise. Results: data suitable for postprocessing were obtained in all subjects. The main findings were: unidirectional wall shear rate waveforms and high wall shear rate (775 s(-1) +/- 167 s(-1)) at the flow, divider; low wall shear rate (60 s '+/- 40 s(-1)) and a high oscillation index with huge interindividual variation (85 +/- 65) at the lateral wall. Conclusion: these are the first in vivo data describing, in detail, the forces of the blood acting on the wall of the carotid bifurcation. The results do not contradict the hypotheses associating low and oscillating wall shear stress with the development of atherosclerosis.