3D biplanar statistical reconstruction of scoliotic vertebrae

Abstract

A new 3D reconstruction method of scoliotic vertebrae of a spine, using two calibrated conventional radiographic images (postero-anterior and lateral), and a global prior knowledge on the geometrical structure of each vertebra is presented. This geometrical knowledge is efficiently captured by a statistical deformable template integrating a set of admissible deformations, expressed by the first modes of variation in the Karhunen-Loeve expansion of the pathological deformations observed on a representative scoliotic vertebra population. The proposed reconstruction method consists in fitting the projections of this deformable template with the preliminary segmented contours of the corresponding vertebra on the two radiographic views. The 3D reconstruction problem is stated as the minimization of a cost function for each vertebra and solved with a gradient descent technique. The reconstruction of the spine is then made vertebra by vertebra. The proposed method allows also to efficiently obtain an accurate 3D reconstruction of each scoliotic vertebra and, consequently, it allows also to get an accurate knowledge of the 3D structure of the whole scoliotic spine. This reconstruction method is in final phase of validation.