Camevale M, Jones J, Sponenberq P, et al.
Introduction/Purpose: Sacroiliac joint disease is increasingly being recognized as one of the causes of lower back pain in dogs. Diagnosis is currently based primarily on clinical examination and radiography, with necropsy considered to be the reference standard. Computed tomography (CT) has been established as a sensitive, non- invasive test for ante-mortem diagnosis of sacroiliac joint disease in humans with lower back pain. The purpose of this study was to test the hypothesis that CT and gross pathology will agree for detecting lesions consistent with sacroiliac joint disease in a group of dogs.
Methods: Digital CT scans and corresponding gross pathology slice photographs of the sacroiliac region were retrieved from data previously acquired for a cadaver study on ultrasound sacroiliac-guided injection in dogs. Fifteen, adult, mixed breed dogs were evaluated (30 sacroiliac joints). A pre-veterinary student (MC) and a veterinary radiologist (JJ) reviewed CT images and recorded presence or absence of the following CT lesions previously reported to be characteristics of clinically significant sacroiliac joint disease in humans: subchondral cyst, subchondral sclerosis, subchondral erosions, intra-articular ankylosis, and para-articular ankylosis. Findings were recorded in three independent review sessions separated at least a week apart, with the order of dogs randomized between reading sessions. A fourth reading session was then used to resolve any discordant interpretations. A veterinary pathologist (PS) reviewed gross pathology slice photographs using the same protocol and recorded presence or absence of the same lesions as those described above. Data recorded during the 4th reading session for each test were used for statistical comparisons. A statistician (IH) compared agreement between CT and gross pathology for sacroiliac joint lesion detection using McNemar’s test and Kappa statistics.
Results: In this sample of 15 dogs , prevalence of lesions consistent with sacroiliac joint disease was 100% based on CT and 100% based on gross pathology slices. More subchondral cyst and intra-articular ankylosis lesions were detected using CT versus gross pathology. More subchondral sclerosis and subchondral erosion lesions were detected using gross pathology versus CT. Para-articular ankylosis was detected only with CT. Proportions of detected subchondral cyst lesions differed between CT and gross pathology for left and combined right/left sacroiliac joints (p 0.05, McNemar’s). Overall agreement was poor between CT and gross pathology for detection of subchondral cyst , subchondral sclerosis , subchondral erosion , and intra-articular ankylosis lesions in combined right/left sacroiliac joints (Kappa 0.20).
Discussion/Conclusion: Findings failed to support our hypothesis that sacroiliac lesion detection for CT and gross pathology will agree. Previous human studies have proposed that CT may be a better reference standard than necropsy for some bone lesions. Future studies are needed to determine whether the same may be true for sacroiliac joint lesions in dogs.