Soutenance de thèse : Hao XU

Three-dimensional quantitative analysis of bone microvasculature in synchrotron micro-CT imaging

Doctorant : Hao XU

Laboratoire INSA : CREATIS

Ecole doctorale : EDA160 : Electronique, Electrotechnique, Automatique

The three-dimensional (3D) imaging and quantitative analysis of bone microvasculature are important to describe angiogenesis involvement in bone metastatic processes. Here, we propose an algorithm based on marker controlled watershed for the 3D segmentation of vessels and bone in mouse bone imaged with a vessel contrast agent using synchrotron radiation micro-computed tomography (SR-µCT). Markers are generated using hysteresis thresholding and morphological filters, and the control surface is constructed using the monogenic signal phase asymmetry. The accuracy and robustness of the proposed method were evaluated on a series of synthetic volumes generated to mimic the vessel, bone and background structures. Different contrasts between the different structures, as well as different noise levels were considered. A series of multi- class synthetic volumes were segmented using the proposed method, and the overall segmentation quality was evaluated using the Matthews correlation coefficient (MCC) by comparing to the ground truth. In addition, we evaluated the segmentations of thin structures under various levels of Gaussian noise. The simulation study indicates that the algorithm is performant in other multi-class segmentation problems. The algorithm was applied to images of bone from a mouse model of breast cancer bone metastasis acquired using SR-µCT. The segmentation quality was evaluated using the Dice coefficient and the MCC by comparing to manual segmentation. The proposed method performs better than hysteresis thresholding as well as marker-controlled watershed using the magnitude of the gradient as control surface. Several quantitative parameters on bone and vessels were extracted. This demonstrates the effectiveness of the algorithm for the study of bone and vessel microstructures in mouse models.