Predictive Value of Magnetic Resonance Imaging in Patients With Juvenile Idiopathic Arthritis in Clinical Remission

OBJECTIVE: To define the prevalence of subclinical synovitis on magnetic resonance imaging (MRI) in a large cohort of patients with juvenile idiopathic arthritis (JIA) in clinical remission and to evaluate its predictive value in terms of disease flare and joint deterioration. METHODS: Ninety patients with clinically inactive JIA who underwent a contrast‐enhanced (CE)–MRI of a previously affected joint were retrospectively included. Each joint was evaluated for synovitis, tenosynovitis, and bone marrow edema. Baseline and follow‐up radiographs were assessed to evaluate structural damage progression. RESULTS: CE‐MRI was acquired in 45 wrists, 30 hips, 13 ankles, and 2 knees. Subclinical synovitis was detected in 59 (65.5%) of 90 patients and bone marrow edema in 42 (46.7%) of 90 patients. Fifty‐seven of 90 (63.3%) patients experienced a disease flare during follow‐up. Forty‐four of 59 (74.6%) patients with subclinical synovitis experienced a disease flare versus 13 (41.9%) of 31 patients with no residual synovitis on MRI (P = 0.002). The presence of subclinical synovitis was the best predictor of disease flare on multivariable regression analysis (hazard ratio [HR] 2.45, P = 0.003). Baseline and follow‐up radiographs were available for 54 patients, and 17 (31.5%) of 54 patients experienced radiographic damage progression. The presence of bone marrow edema (HR 4.40, P = 0.045) and being >17 years old (HR 3.51, P = 0.04) were strong predictors of joint damage progression in the multivariable analysis. CONCLUSION: MRI‐detected subclinical inflammation was present in a large proportion of patients with JIA despite clinical remission. Subclinical synovitis and bone marrow edema have been shown to play a role in predicting the risk of disease relapse and joint deterioration, with potential implications for patients' management of the disease.