Diagnosis and progression of sacroiliitis in repeated sacroiliac joint computed tomography.

Objective. To assess the clinical utility of repeat sacroiliac joint computed tomography (CT) in sacroiliitis by assessing the proportion of patients changing from normal to pathologic at CT and to which degree there is progression of established sacroiliitis at repeat CT. Methods. In a retrospective analysis of 334 patients (median age 34 years) with symptoms suggestive of inflammatory back pain, CT had been performed twice, in 47 of these thrice, and in eight patients four times. The studies were scored as normal, equivocal, unilateral sacroiliitis, or bilateral sacroiliitis. Results. There was no change in 331 of 389 repeat examinations. Ten patients (3.0%) had progressed from normal or equivocal to unilateral or bilateral sacroiliitis. Of 43 cases with sacroiliitis on the first study, 36 (83.7%) progressed markedly. Two normal cases had changed to equivocal. Eight equivocal cases were classified as normal on the repeat study. In further two patients, only small changes within the scoring grade equivocal were detected. Conclusions. CT is a valuable examination for diagnosis of sacroiliitis, but a repeated examination detects only a few additional cases of sacroiliitis. Most cases with already established sacroiliitis showed progression of disease

The Validity of the New York Radiological Grading Criteria in Diagnosing Sacroiliitis by Computed Tomography

Background: Sacroiliitis in ankylosing spondylitis has frequently been graded radiographically using the New York (NY) criteria, which also have been applied in computed tomography (CT). Purpose: To validate the grading of the NY criteria in CT of the sacroiliac joints. Material and Methods: With the aid of the NY criteria, assessment of inflammatory and degenerative changes was made in 1304 CT studies. Assessment included erosions, the distribution, type, and width of sclerosis, and the involvement of the joints in sacroiliitis, as well as of normal anatomic variants such as joint space width and shape. Results: There was definite radiological sacroiliitis in 420 joints in 251 patients. Among these, more than two-thirds of the joint was involved in 71.0% of the affected joints. Sclerosis of the ilium was much more prevalent than sacral sclerosis. With increasing NY grade, iliac sclerosis, width, and extent increased, transition from sclerosis to normal bone became indistinct, and the structure of sclerosis was more inhomogeneous. Erosions of the joint surfaces were localized predominantly on the iliac side. Conclusion: Only erosions seem to be a valid solitary diagnostic sign. Solitary erosions need supplemental evidence from other inflammatory signs. Inflammatory sclerosis may be distinguished from degenerative sclerosis, and can sometimes support early diagnosis. Joint space width, joint shape, bone mineral content, or enthesopathy have no place in sacroiliitis diagnosis on CT. The NY criteria are not ideal for use with CT. A practical classification of sacroiliitis on CT is proposed, with a grading of no disease, suspected disease, and definite disease

The clinical utility of computed tomography compared to conventional radiography in diagnosing sacroiliitis. A retrospective study on 910 patients and literature review

Objective. Ankylosing spondylitis (AS) is a progressive, debilitating disease with complex symptoms, unclear etiology and pathogenesis, and difficult diagnosis. Current imaging methods are useful in diagnosing AS and other spondyloarthropathies, and are frequently used in investigations of sacroiliitis. The radiographic diagnosis of sacroiliitis has large interobserver variations. Computed tomography (CT) has been used for evaluation of sacroiliitis since 1979, and has been evaluated in several studies, most of them with a limited number of patients. These studies have shown a large number of false-negative results from radiography. Methods. In a retrospective study of clinical data, we evaluated 910 patients with AS who were examined by radiography and CT within a 2-year period. The reported outcomes from radiography and CT were compared. Results. The agreement between radiography and CT data was only fair, with a kappa value of 0.2418. There were 35.0% false-positive radiography reports, 22.5% false-negative radiography reports, and 86.0% false-equivocal radiography reports. In total, 41.3% of all radiological reports gave a false answer. While the number of false negatives was similar to that previously reported, the number of false positives was much higher than previously reported, and is probably similar to everyday radiology reporting. Conclusion. Our results indicate that the clinical utility of radiography for evaluation of sacroiliitis is limited. The high rate of inaccurate results should motivate the use of sectional imaging for its superior performance