Spinal alignment measurement in standing position using stereo-view roentgenography without positional calibration

In the treatment of the spine, knowledge of spinal alignment in a standing position, specifically the relative three-dimensional positional relationship between the vertebrae comprising the spine, is very important. In spinal medicine at present, this is generally measured using two-dimensional X-ray images, but it is difficult to measure three-dimensional changes such as the axial rotation of the vertebra. For this reason, measurement techniques have been proposed which use 2Ds3D registration methods, three-dimensional statistical models, and the correspondence of interest points in the images. However, these techniques require the use of special equipment and the acquisition of the position of the X-ray imaging device; this is not practical for clinical applications. In this paper, the authors propose a spinal alignment measurement technique which employs only medical equipment which is in general use. In the proposed method, spinal alignment is measured by simultaneously estimating the positions of the vertebrae comprising the spine and the position of the X-ray imaging device. The proposed technique makes possible three-dimensional spinal alignment measurement without changes to current spinal medicine protocols. In this paper, the authors conducted a computer simulation experiment and an experiment using real images, compared the performance of the proposed method with that of conventional methods, and verified the properties of the proposed method. As a result, it was confirmed that the proposed method is effective for measuring the relative positions of vertebrae, as in spinal alignment. © 2007 Wiley Periodicals, Inc. Syst Comp Jpn, 38(2): 32– 45, 2007; Published online in Wiley InterScience (). DOI 10.1002sscj.20663