AB1421 DOES THE SACROILIAC JOINT MAGNETIC RESONANCE IMAGING ENHANCE THE ENTHESITIS-RELATED ARTHRITIS DIAGNOSIS?

Abstract

BackgroundMagnetic Resonance Imaging (MRI) is the gold standard in the diagnosis of adult spondyloarthritis [1]. MRI sensitivity and specificity seem to be less studied in juvenile spondyloarthritis, especially in Enthsitis-related Arthritis (ERA).ObjectivesWe aimed to determine the sensitivity and specificity of MRI in the diagnosis of ERA.MethodsWe conducted a retrospective study including 44 patients with Juvenile Idiopathic Arthritis (JIA) meeting the International League of Associations for Rheumatology (ILAR) 2001 criteria. For each patient, we collected the following data: age, age at the onset of JIA, JIA subtype, disease duration, C-reactive protein (CRP), HLA-B27 typing, and Erythrocyte sedimentation rate (ERS) levels. Each patient had a sacroiliac joint MRI. Sacroiliitis was defined using the OMERACT JAMARIS scoring system [1]. Disease activity was assessed using the JSpADA score for ERA and JADAS-CRP-10 for the rest of the JIA subtypes. We divided patients into two groups: Group 1 (G1) patients with ERA and Group 2 (G2) patients with non-ERA subtype.Statistical analysis was performed using SPSS software.ResultsWe included 28 boys and 16 girls. The mean age was 13.65 ± 4.62 years. The mean age at the onset of the disease 9.57 was ± 3.97 years. The mean disease duration was 4.34 ± 3.09 years. There was enthesitis-related arthritis in 61% of the cases (n=27), oligoarticular JIA in 14% of the cases (n=6), polyarticular JIA in 11% of the cases (n=5), and psoriatic arthritis in 7% of the cases (n=3). JIA was undifferentiated in 7% of the cases (n=3). Sacroiliac joints were painful in 15 patients (34%). The mean CRP and ESR were 14.42 ± 19.67mg/L and 26.56 ± 20.87mm, respectively. The mean JADAS and JSpADA were 6.6 ± 4.7 and 3.09 ± 1.55, respectively. HLA-B27 was performed in 22 patients and was positive only in five patients.IRM was normal in 25 patients (57%) (G1: 11 versus G2:14) and showed bone marrow in the sacroiliac joints in 19 patients (34%) (G1=16 versus G2=3, p=0.005).The sensitivity and specificity of the sacroiliac joints MRI in the diagnosis of ERA were 61.54% and 82.35%, respectively. Positive predictive value and negative predictive value were 84.21% and 58.33%, respectively. Furthermore, sacroiliac joint pain in the clinical examination was able to predict sacroiliac bone edema in MRI with an odds ratio of 6.8 (95% confidence interval 1.68 to 28.09; p=0.006).ConclusionAccording to other studies, ours showed that MRI inflammatory lesions could be observed in JIA regardless of JIA sub-types [2]. Interestingly, we found that MRI abnormalities were not sensitive but had a good specificity in the diagnosis of ERA. Thus, MRI could guide the diagnosis of ERA but could not be the gold standard in this disease.