Objective. To investigate mechanisms involved in inflammation and new bone formation in the sacroiliac (SI) joints of patients with ankylosing spondylitis (AS).Patients and methods. Computed tomographyassisted biopsy of the SI joint was performed in 5 patients with AS with a mean disease duration of 4.5 years and radiographic stage 2-3 disease. Immunohistologic studies were performed with the alkaline phosphatase-anti-alkaline phosphatase technique, and cytokine messenger RNA (mRNA) was detected by in si tu hybridization.Results. Dense cellular infiltrates with varying amounts of CD3+ cells (mean f SD 53.3 f 24.1%), CD4+ cells (29.7 f 17.6%), CDS+ cells (15.8 f 11.4%), CD14+ cells (23.6 f 16.9%), CD45RO+ cells (48.4 f 23.6%), and CD45RA+ cells (4.5 f 2.9%) were found in the synovial portion of the SI joints of all 5 patients. In these infiltrates a high amount of tumor necrosis factor a (TNFa) mRNA and, near the site of new bone formation, a lower amount of transforming growth factor / 3 (TGFP) mRNA, were detected, while no message for interleukin-1 was found in the 3 patients examined by this technique.Conclusion.

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Objective. To evaluate the new magnetic resonance imaging (MRI) method of dynamic MRI with fast imaging in the diagnosis of sacroiliitis among patients with spondylarthropathy.Methods. Fifteen patients with a history of inflammatory back pain without radiographic evidence of grade I1 or greater sacroiliitis (group l), 25 patients with definite ankylosing spondylitis (group 2), and 12 patients with noninflammatory spinal pain (controls) (group 3) were examined. Dynamic MRI with fast imaging was performed after intravenous bolus injection of the contrast agent gadolinium4iethylenetriamine pentaacetic acid. The degree of enhancement was graded as representing acute sacroiliitis, latent sacroiliitis, or no sacroiliitis.Results. Acute sacroiliitis was detected in 22 of 30 sacroiliac (SI) joints in group 1 patients and in 27 of 50 SI joints in group 2 patients; latent sacroiliitis was seen in 25 of 80 SI joints in patients from groups 1 and 2. No group 3 patient was found to have sacroiliitis.Conclusion. Early sacroiliitis can be demonstrated by dynamic MRI in spondylarthropathy patients in whom abnormalities are not revealed by conventional radiography.

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Contrast-enhanced MR imaging allows detection of sacroiliitis in early stages.