Computer aided vertebral visualization and analysis: a methodology using the sand rat, a small animal model of disc degeneration

BackgroundThe purpose of this study is to present an automated system that analyzes digitized x-ray images of small animal spines identifying the effects of disc degeneration. The age-related disc and spine degeneration that occurs in the sand rat (Psammomys obesus) has previously been documented radiologically; selected representative radiographs with age-related changes were used here to develop computer-assisted vertebral visualization/analysis techniques. Techniques presented here have the potential to produce quantitative algorithms that create more accurate and informative measurements in a time efficient manner.MethodsSignal and image processing techniques were applied to digitized spine x-ray images the spine was segmented, and orientation and curvature determined. The image was segmented based on orientation changes of the spine; edge detection was performed to define vertebral boundaries. Once vertebrae were identified, a number of measures were introduced and calculated to retrieve information on the vertebral separation/orientation and sclerosis.ResultsA method is described which produces computer-generated quantitative measurements of vertebrae and disc spaces. Six sand rat spine radiographs illustrate applications of this technique. Results showed that this method can successfully automate calculation and analysis of vertebral length, vertebral spacing, vertebral angle, and can score sclerosis. Techniques also provide quantitative means to explore the relation between age and vertebral shape.ConclusionsThis method provides a computationally efficient system to analyze spinal changes during aging. Techniques can be used to automate the quantitative processing of vertebral radiographic images and may be applicable to human and other animal radiologic models of the aging/degenerating spine.

[1]  J. Adler,et al.  Comparison of truncal and caudal lesions in the vertebral column of the sand rat (Psammomys obesus). , 1983, Israel journal of medical sciences.

[2]  R. Moskowitz,et al.  Physicochemical properties of the aging and diabetic sand rat intervertebral disc , 1992, Journal of orthopaedic research : official publication of the Orthopaedic Research Society.

[3]  T J Masaryk,et al.  Degenerative disk disease: assessment of changes in vertebral body marrow with MR imaging. , 1988, Radiology.

[4]  Thomas S. Huang,et al.  Image processing , 1971 .

[5]  Norbert Wiener,et al.  Extrapolation, Interpolation, and Smoothing of Stationary Time Series , 1964 .

[6]  P P Smyth,et al.  Vertebral shape: automatic measurement with active shape models. , 1999, Radiology.

[7]  E Schneider,et al.  Structure and Function of Vertebral Trabecular Bone , 1997, Spine.

[8]  P Kurowski,et al.  The Relationship of Degeneration of the Intervertebral Disc to Mechanical Loading Conditions on Lumbar Vertebrae , 1986, Spine.

[9]  L. Rodney Long,et al.  Use of shape models to search digitized spine X-rays , 2000, Proceedings 13th IEEE Symposium on Computer-Based Medical Systems. CBMS 2000.

[10]  J. Adler,et al.  Degeneration of the intervertebral disks and spondylosis in aging sand rats. , 1979, Archives of pathology & laboratory medicine.

[11]  R. A. Silverman,et al.  Extraction of Signals from Noise. , 1963 .

[12]  Lewis E. Berman,et al.  Digital atlas for spinal x rays , 1997, Medical Imaging.

[13]  Milan Sonka,et al.  Image Processing, Analysis and Machine Vision , 1993, Springer US.

[14]  Sung Yong Shin,et al.  Image Metamorphosis with Scattered Feature Constraints , 1996, IEEE Trans. Vis. Comput. Graph..

[15]  I W Nelson,et al.  Mechanical initiation of intervertebral disc degeneration. , 2000, Spine.

[16]  R. Cailliet,et al.  Vertebral End-Plate Changes With Aging of Human Vertebrae , 1982, Spine.

[17]  H. Gruber,et al.  The Sand Rat Model for Disc Degeneration: Radiologic Characterization of Age-Related Changes: Cross-sectional and Prospective Analyses , 2002, Spine.

[18]  R. Silberberg.  The vertebral column of diabetic sand rats (Psammomys obesus). , 1988, Experimental cell biology.

[19]  Mohan M. Trivedi,et al.  Localized Radon transform-based detection of linear features in noisy images , 1994, 1994 Proceedings of IEEE Conference on Computer Vision and Pattern Recognition.

[20]  Simon Cox,et al.  Optimising the application of the hough transform for automatic feature extraction from geoscientific images , 1998 .

[21]  R. Silberberg,et al.  Histologic and Morphometric Observations on Vertebral Bone of Aging Sand Rats , 1988, Spine.

[22]  R. Moskowitz,et al.  Spondylosis in sand rats: A model of intervertebral disc degeneration and hyperostosis , 1990, Journal of orthopaedic research : official publication of the Orthopaedic Research Society.

[23]  J. Adler,et al.  Early Onset of Disk Degeneration and Spondylosis in Sand Rats (Psammomys Obesus) , 1983, Veterinary pathology.

[24]  L. Rodney Long,et al.  Identification and classification of spine vertebrae by automated methods , 2001, SPIE Medical Imaging.