Radiology of the vertebral column

Radiographic assessment of the vertebral column is usually perfomed to investigate suspected disorders of the vertebral column and paravertabral soft tissues. As the spinal cord and nerves are not visible on survey radiographs, diagnostic conclusions are mainly drawn indirectly from its casing, the vertebral column. Therefore, it is not surprising that survey spinal radiography has a poor diagnostic yield in animals with neurological disease. There are challenges associated with radiography of the vertebral column. For example localization, accurate neurolocalization is required and should precede radiography to ensure that the correct spinal cord segments are imaged and to rule out multifocal disease. Paired structures (articular processes, pedicles) are superimposed on lateral views, and cardiovascular structures and the bowel are superimposed on the vertebral column on ventrodorsal (VD) views, creating multiple composite shadows which can mimic pathology. There is poor contrast of the paraspinal soft tissues and the soft tissues within the vertebral canal. Also, radiography is relatively insensitive for demonstrating bone loss. Considerable bone loss (30-50%) is required before changes are recognized on radiographs.