Abstract : This research topic is related to the previous Sharp team project. It will be ended at the end of 2005 (with the Miriam Amavizca's ph-D). This year, a paper related to our previous work on the dynamic and interactive simulation applied to an echographic medical procedure, has been published in a medical journal.
We have worked in computer aided surgery for the Total Hip Prosthesis (THP) in collaboration with Aesculap-BBraun. The aim of the project is to obtain a CT/MRI-free 3D volume generation of the hip for preoperative planning and navigation, and operative guidance for a normal hip. The approach is to obtain an approximation of the real 3D hip volume of the patient by deforming a nominal 3D hip mesh. The deformation consists in driving a set of control points on the hip mesh, in order to match specific positions (atlas hip) provided by 2D radiographic data and 3D echographic data of the patient. Our goal is to use the obtained 3D volume for the preoperative planning and navigation. In the preoperative planning the 3D hip volume will allow the surgeon to select the prosthesis type(size and form) and position. The 3D volume will be used to guide the surgeon in the prosthesis implantation providing the 3D position and orientation of the patient's hip and of the surgical tools.
In 2005, we have made two main contributions to this approach :
* a study of the exploitable characteristics of hip and femur for 3D model reconstruction,
* a methodology for 3D hip volume reconstruction using minimally invasive imagining techniques: a single radiographic image (2D data) and a few echographic images (3D data).
We have defined the set of the selected caracteristic hip points as an ``probabilistic atlas'' of the hip. This atlas is then used for the above mentionned 3D hip volume reconstruction method. The method consists of three main stages : (i) data acquisition of the radiographic and echographic images of the patient hip, (ii) inference of the hip atlas of the patient and (iii) 3D hip volume reconstruction using a mesh deformation mechanism exploiting the data given by the atlas and by the medical images. These stages pose different problems related to the representation of the generic atlas of the hip, to the inference process, and to the radiographic and echographic data processing. To solve this problematic we have used Bayesian techniques. This is detailed in the thesis of Miriam Amavizca .