In vitro 4 MHz NMR proton relaxation times and in vitro mechanical behavior at low extension of human common carotid arterial wall

We investigated the influence of the biomechanical behavior of human common carotid arterial wall on the NMR proton relaxation times using a Bruker Minispec at 4 MHz. The study was limited to low extension in simple longitudinal elongation of the carotid wall (the maximum loading stretch ratio being 40%). Twenty-five carotid samples divided into 2 longitudinal strips were tested. The first strip was used to determine the nondimensional elastic parameter alpha according to the mechanical model of Fung. The second strip was used to measure the proton relaxation times. T1 value was 316.8 ms +/- 27.6 and T2 value was 59.9 ms +/- 6.8. A significant linear correlation was found between T1 and Ln alpha (p = 0.02). T1 and T2 were not correlated to the age but linearly correlated to the tissue water content (p less than 0.0001), however the age and alpha were not correlated to the tissue water content. These results may reflect the differences in the amount of water binding sites of the elastin which is involved in the elasticity of the carotid wall at low extension.