Enteropathic arthritis in the sacroiliac joint. Imaging and differential diagnosis

Objectives: A new high resolution computed tomography (HRCT) scoring system of sacroiliac joint (SIJ) involvement in enteropathic arthritis is introdu ced. Patients and methods: SIJ's of 100 patients were studied. A total of 2 5 patients presented with pain syndrome, 25 with suspicious seronegative sp ondylarthritis, 25 with inflammatory bowel diseases and 25 without joint or bowel diseases, as a control group. HRCT was carried out in all 100 patien ts. For comparison, a plain film radiography (PFR), conventional CT (slices of 10 mm) and bone scan were used. Results: Quantitative differences: In t he pain syndrome group, there were no erosions identified neither intraarti cular calcifications. Disc degeneration was seen in 12/25 cases. In 4/25 pa tients, vacuum phenomena appeared in the SIJ. in 3/25 patients, ventral cap sular calcification occurred in the Ventral sacroiliac ligament (anterior c apsule complex). In the seronegative spondylarthritis group, 16/25 patients had positive findings, while PFR documented erosions only in 3/25 cases. T n the bowel diseases group, erosions were detected in 17/25 cases with HRCT , while the plain film was positive only in three cases and in seven cases the findings were questionable. Intraarticular calcification with erosion w as documented in three cases and in seven cases without erosion. The bone s can was positive in 7/25 of this cases, but in 5/7 there was mismatching wi th HRCT. Important new finding was the HRCT detected erosion which was not detected on BS but was obvious on Anti-Granulocyte-Antibody scintigraphy. I n the control group, only degenerative changes were seen in 4/25 cases and no erosions. Conclusion: HRCT is: (1) the reliable imaging of definitive (o ften 'cold stage') sacroileitis; (2) gives optimal detection of erosion; an d (3) appears to be the only method in the documentation of calcifications in the posterior ligamental portion of the SIJ. (C) 2000 Elsevier Science I reland Ltd. All rights reserved.