Tiam Mana Saffari

81 OBJECTIVE EVALUATION OF ANGIOGENESIS USING MICRO CT AND PHOTOGRAPHY 4 nerve graft implementationmay provide insight to the ratio between revascularization components. These techniques may demonstrate the relationship between vessel alignment and the level of nerve regeneration. Thus, allowing us to improve our understanding of the process and the importance of vascular development in nerve grafts. As blood vessels provide little inherent contrast, viscosity is one of the most important properties of the implemented vehicle 15 . With viscosity levels around 20-30, Microfil® is the best available compound that injects both the arterial and venous system and reaches even the smallest angiogenic vessels to allow complete study of the vascular network 15 . The injected Microfil® does not directly interact with the histology but could influence the proportion of axon and nerve areas during the analysis. Therefore, we would suggest harvesting other tissue prior to Microfil® injection to secure reliable histologic analysis. There are a few considerations associated with this technique. Although micro CT systems become more commonly available with improving quality 15 , it is still conceivable that micro CT devices with small effective voxel size are not available for all researchers. In this case, solely the described conventional photography strategy could be used, as it is cost-effective, simple to perform and correlates with micro volume measurements. However, conventional photography does not describe vascularization in space and lacks detailed information. As only two sides of the nerve sample are measured and the surface area could not be corrected for the thickness of the nerve (i.e. depth of the obtained photo), representation of the amount of angiogenesis using vascular surface area may be questionable. The difference between various groups of nerve samples, however, could be described with conventional photography. The micro CT has the advantage of precisely measuring vessel volume in relation to total measured nerve volume. Also, clearing of samples is not necessary as the lead pigments in Microfil® provide high contrast compared to background tissue to acquire complete high resolution 3D images of the vessels 17 . Our results indicate the significant correlation between the vascular volume and the vascular surface area measurements demonstrating that the methods could be used either complementary or separately, depending on the goals of the study. These methods will allow us to advance angiogenesis related research by improving the