Computed tomography in the diagnosis of sacroiliitis.

Computed tomography (CT) and conventional radiography of the sacroiliac joint were compared in 43 patients. CT appeared to be far more sensitive and equally specific in the recognition of sacroiliitis. In a number of patients with sacroiliitis diagnosed by both techniques, CT demonstrated abnormalities that were not demonstrated by conventional radiographs. Of those patients with clinical evidence of sacroiliitis and HLA-B27 positivity, 50% had negative or equivocal radiographs compared to 19% who had negative computed tomographic images for sacroiliitis.