Anatomic Distribution of Sacroiliac Joint Lesions on Magnetic Resonance Imaging in Patients With Axial Spondyloarthritis and Control Subjects: A Prospective Cross-Sectional Study, Including Postpartum Women, Patients With Disc Herniation, Cleaning Staff, Runners, and Healthy Individuals.

OBJECTIVE: To investigate the anatomic location and distribution of lesions on magnetic resonance imaging (MRI) in the sacroiliac (SI) joints in patients with axial spondyloarthritis (SpA), women with and without postpartum pain (childbirth within 4-16 months), patients with disc herniation, cleaning staff, runners, and healthy persons. METHODS: In a prospective cross-sectional study of 204 participants, MRI of the entire cartilaginous compartment of the SI joint was scored blindly by 2 independent, experienced readers, according to Spondyloarthritis Research Consortium of Canada definitions of SI joint inflammation and structural lesions in each SI joint quadrant or half and in each of 9 slices. The locations of the lesions (unilateral/bilateral, upper/lower, sacral/iliac, and anterior/central/posterior slices) were analyzed based on concordant reads. RESULTS: Bone marrow edema (BME) occurred in all quadrants in nearly all participant groups, but rarely bilaterally, except in patients with axial SpA and women with postpartum pain. Fat lesions were mainly found in axial SpA and occurred in all quadrants, but mostly bilaterally in sacral quadrants. Erosion was rare, except in axial SpA, where it was mainly iliac and often bilateral. Sclerosis was exclusively iliac and most frequent in women with postpartum pain. CONCLUSION: The location and distribution of common SI joint lesions in axial SpA and non-axial SpA were reported, and group-specific patterns were revealed. BME distributed bilaterally or unilaterally, both locally and more widespread in the SI joint, is common in both postpartum women with pain and axial SpA patients, which limits the use of BME to differentiate these groups. This study indicates that the presence of fat lesions, especially when widespread, and/or erosion, particularly when located centrally or posteriorly, are diagnostically important and should be investigated further.

Detection of antinuclear antibodies by solid-phase immunoassays and immunofluorescence analysis.

BACKGROUND: Antinuclear antibodies (ANAs) are associated with several inflammatory rheumatic diseases. The aim of the present work was to evaluate enzyme immunoassays (EIAs) and compare them with classic immunofluorescent analysis (IFA) for the detection of ANA. METHODS: Seven enzyme immunoassays were used in this study. All assays were applied as described by the manufacturers. Three populations were included in the study: (a) a population of patients with well-established autoimmune inflammatory disease (n = 102); (b) a population in which a rheumatic disease was diagnosed up to 5 years after an IFA was performed (n = 164); and (c) a population of consecutive outpatients suspected to have a rheumatic disease (n = 101). The current clinical diagnoses of the patients served as the standard against which performance of the assays was evaluated. RESULTS: In patients with well-established rheumatic disorders, the newly developed EIA in which HEp-2 extracts were included had sensitivities and specificities comparable to or in some instances better than the IFA. The assays without HEp-2 extracts included had significantly lower sensitivities and specificities. In the outpatient population, up to 51% of patients had positive ANA tests that did not correspond to classic ANA-associated disease. However, in the assays in which the HEp-2 extracts were not included, the false-positive rate was <10%. The false-negative rate judged against IFA differed from assay to assay and disease to disease and was mostly <10%. CONCLUSIONS: In this study, the sensitivities of EIAs and IFA were largely comparable. However, EIAs without HEp-2 extracts included had a low sensitivity but a high specificity, particularly in nonselected populations. The choice of test is highly dependent on the clinical setting in which the ANA test is to be used and on laboratory policy.