Cheon BG, Park SJ, Yoorr JH, et al.
Introduction/Purpose: CT is widely used to investigate the vertebral disorders particularly for pathologic bone changes. Vertebra consists of cortical and cancellous bones and each bone has different density and architecture. We encountered various focal lesions from vertebral CT images showing hyper- or hypoattenuation in dogs withou t pathologic bone disorder. In this study , vertebral bone architecture was investigated in dogs to determine the normal variation of vertebral CT morphology.
Methods: Vertebral CT images taken from Oct. 1, 2011 to May, 31, 2014 were investigated retrospectively in dogs without neoplasia and general diseases affecting on bone density. Vertebral architecture was evaluated at three parts such as the spinous process , transverse process , and body. The trabecular pattern and the location , number and attenuation of abnormal focal lesions were determined.
Results: Twenty dogs of 10 breeds (8 maltese, 2 shihtzu, 2 Yorkshire terrier, 2 mongrel, 1 pekingese, 1 Shetland sheepdog, 1 poodle, 1 beagle, 1 Jindo dog and 1 miniature schunauzer) were included in this study. Normal trabecular pattern was prominent from thoracic and lumbar vertebra. However, the cancellous bone of cervical vertebra did not show coarse architecture. Total 100 vertebral lesions were identified in 14 dogs (4 dogs from cervical , 13 dogs from thoracic, and 7 dogs from lumbar regions) from 10 regions of 63 cervical vertebrae (15.9%), 73 of 247 thoracic vertebra (29.6%) and 10 of 119 lumbar vertebra (8.4%). About 40% of the dogs had hyperattenuating lesions at the 7th or 8th thoracic vertebra. All lesions were located within the vertebral body except three lesions includ ing multiple hypoattenuating lesions in a cervical spinous process , a single hyperattenuating lesion in a thoracic transverse process, and a single hypoattenuating lesion of lamina in a lumbar vertebra. About 87% of all lesions were hyperattenuation and 40% of them were single and 47% were multifocal lesions. Most hypoattenuating lesions were seen as single lesion (12%). Hyperattenuating lesions were not related
with spondylosis deformans. The vertebral lesions did not have significant correlation with age, body weight, gender, and serum concentration of ALT, ALKP, calcium and phosphorus.
Discussion/Conclusion: CT images showed wide variation of vertebral bone architecture in dogs. Single or multifocal vertebral lesions showing hyper- or hypoattenuation were found about 70% of all dogs and 21.7% of all CT scanned vertebrae. These lesions did not have correlation with spondylosis deformans. Vertebral lesions with hyperattenuation could be confused with enostosis or metastatic lesions. Hypoattenuating lesions could be also misinterpreted as metastasis, pseudocyst, pneumatocyst, diskospondylitis, and others. Normal variation of vertebral bone architecture in CT images should be considered to prevent misdiagnosis as pathologic lesions in dogs.