Combined SCP and Geometric Reconstruction of Spine from Biplanar Radiographs

Three-dimensional reconstruction of the spine is necessary in proper diagnosis of various spinal deformities. This is normally achieved using stereo-radiographic techniques involving biplanar (frontal and lateral) radiographs. Either stereo-corresponding point (SCP) algorithm or non-stereo-corresponding point (NSCP) algorithm is used for this purpose. The NSCP technique suffers from observer variability. Moreover, it is time consuming. Hence, it has restricted usage in clinical environment. Here, a hybrid approach is proposed in which a 3D spine model is reconstructed by applying geometric features to the SCP reconstructed model. The vertebral orientation features are automatically extracted from the calibrated radiographs. The 3D model thus produced is successfully validated. The proposed method has lesser observer variability due to the limited number of anatomical landmarks. Also, the reconstruction errors are within the acceptable limits available in the literature. Thus, the proposed technique can be used in clinical practices for the diagnosis of spinal deformities.