Morphological Analysis of Fenestrae in Arteries

Abstract

Cardiovascular disease (CVD) is worldwide cause of death. The morphological structure of one of the regions of arteries called the internal elastic lamina (IEL) is associated with the stiffness of arteries, especially the presence and characteristics of small holes called fenestrae. Structural analysis of the IEL as observed with multiphoton or confocal fluorescent microscopy is complicated, primarily due to is three-dimensional distribution along a series of z-stack slices. In addition, whilst the top slices of an artery cross long lamina sections, the bottom slices only cross short sections of the lamina and would be better observed in a different plane than that of the acquired image.

In this work, we describe a framework to analyse 3D stacks of arteries as observed with fluorescent multiphoton microscopy. We apply this framework to the study of arterial stiffness as inferred from the presence/absence of fenestra the IEL and their morphological characteristics. The framework assumes the arteries as cylinders, then performs a series of geometrical transformations to align the data in three dimensions. The IEL is segmented from the external elastic lamina (EEL) and then each lamina is projected to a plane from which the fenestrae of all slices can be analysed in a single 2D image. The fenestrae are segmented by filtering with a Laplacian of a Gaussian kernel with optimal parameters. The results were compared against manually segmented fenestrae and provided a classification accuracy of [98–99%] and Jaccard Index values in the range of [38–54%], which are comparable the variations of 3 independent manual segmentations. The code is available from the website https://github.com/reyesaldasoro/Arterial-Fenestrae.