Radiographic diagnosis of sacroiliitis - Are sacroiliac views really better?

Objective. To determine whether detailed oblique radiographs of the sacroil iac (SI) joints provide significant diagnostic advantage to a single AP pro jection of the pelvis in establishing the presence and severity of sacroili itis. Methods, Radiographs (both AP pelvis and detailed oblique projections) of 4 45 right SI joints and 442 left SI joints were obtained from patients with an established diagnosis of a seronegative spondyloarthropathy, and interpr eted for severity. Data for the right and left SI joints were analyzed, com paring interpretations of severity based on AP pelvis projections with obli que views. Results, Analysis of these data showed an agreement rate between AP views a nd SI views of 89.7% for the right SI joint radiographs and 86.4% for the l eft SI joint. There was no instance in which a patient with "unequivocal ab normalities" of the SI joints on the AP pelvis was read as having "normal" SI views. Similarly, there were no cases in which "normal" SI joints on AP pelvis films were read as having unequivocal abnormalities on SI views. Conclusion. In this group of patients with seronegative spondyloarthropathi es, there was very close agreement between severity score of sacroiliitis f rom AP pelvis radiographs and SI joint views. We conclude that in most circ umstances, the AP pelvis film will yield the diagnosis of sacroiliitis with out the additional radiation exposure and expense related to specific SI jo int radiographs.