Novel optical system for in vitro quantification of full surface strain fields in small arteries: II. Correction for refraction and illustrative results

In a companion paper, we described a theoretical foundation for and initial experimental implementation of a novel stereo-digital image correlation (DIC) method for quantifying the size, shape and deformation of small cylindrical specimens along their full length and around their entire circumference. In this paper, we further show that this panoramic-DIC method can be used to study mouse carotid arteries without affecting their native mechanical properties and show the advantage of the approach in studying more complex mouse aorta. In particular, we first resolve the ubiquitous issue of refraction in non-contacting optical measurements of strain while tissues are immersed in physiologic saline and we show that surface preparation for DIC does not affect the inferred mechanical properties either qualitatively or quantitatively, the latter via the use of a four-fibre family hyperelastic constitutive relation and associated estimation of material parameters using nonlinear regression. We thus submit that panoramic-DIC-based strain measurement has significant potential to increase our understanding of arterial mechanics in genetic models of arterial health and disease by allowing investigators to exploit advances in transgenic mice.