EARLY SACROILIITIS IN PATIENTS WITH SPONDYLOARTHROPATHY - EVALUATION WITH DYNAMIC GADOLINIUM-ENHANCED MR-IMAGING

PURPOSE: To investigate the diagnostic value of gadolinium-enhanced magnetic resonance (MR) imaging in the detection of early sacroiliitis. MATERIALS AND METHODS: Of 125 patients with back pain, 72 had inflammatory back pain and had a diagnosis of spondylarthropathy; the other 53 patients had other mostly mechanical causes of back pain and served as the control group. The 72 patients with spondyloarthropathy were further subdivided into two groups according to established radiographic criteria for ankylosing spondylitis. While group 2 patients (n = 36) with a diagnosis of ankylosing spondylitis had definite radiographic changes in the sacroiliac joints, group 1 patients (n = 36) with undifferentiated spondylarthropathy had no such findings. RESULTS: While no contrast enhancement was found in normal sacroiliac joints, significantly different degrees of enhancement (P <.05) related to the patients' degree of pain were clearly detected in both groups of patients with spondyloarthropathy. Contrary to the mostly normal findings with precontrast MR imaging and with radiography, dynamic MR imaging revealed small erosions (<1 mm) in 47 (72%) of the 65 inflamed joints in group 1 and juxtaarticular osteitis in 53 (82%). CONCLUSION Contrast-enhanced MR imaging allows detection of sacroiliitis in early stages.