Juvenile idiopathic arthritis: magnetic resonance imaging of the clinically unaffected knee

E Charlotte Van Gulik,J Merlijn Van Den Berg,Dieneke Schonenberg-Meinema,Robert Hemke,Mendy M Welsink-Karssies,Anouk M Barendregt,Taco W Kuijpers,Mario Maas,Charlotte M Nusman,Koert M Dolman

doi:10.1007/s00247-017-4059-7

Abstract

BackgroundSynovial thickening detected on magnetic resonance imaging (MRI) is present in a significant number of children with clinically inactive juvenile idiopathic arthritis (JIA).ObjectiveTo evaluate patient characteristics and disease activity parameters in a cohort of children with clinically inactive JIA, both with and without synovial thickening, in order to clarify the observed discrepancy between clinical and MRI assessments.Materials and methodsWe prospectively enrolled 52 clinically inactive JIA patients (median age 13.3 years, 63.5% girls) who underwent MRI of the knee as major target joint in JIA. Children were divided into two groups based on MRI outcome: group 1, with synovial thickening on MRI; and group 2, with no synovial thickening on MRI. We used the Juvenile Arthritis MRI Scoring system to evaluate synovial thickness. We compared patient characteristics and disease activity parameters between the groups.ResultsSynovial thickening on MRI was present in 18 clinically inactive patients (group 1, 34.6%). The age was significantly lower for the patients in group 1 (median 10.7 versus 14.4, P=0.008). No significant differences were observed in any of the other patient characteristics nor the disease activity parameters tested.ConclusionSynovial thickening on MRI was present in nearly 35% of the children with clinically inactive JIA. Children with synovial thickening on MRI were significantly younger than those without. This might indicate that younger patients are at risk of subclinical disease activity and under-treatment, although the exact clinical relevance of synovial thickening on MRI has not been determined.

Highlights

Juvenile idiopathic arthritis (JIA) is the most common cause of chronic joint inflammation in childhood and represents one of the leading causes of pediatric acquired disability [1]
On magnetic resonance imaging (MRI), thickened synovium (≥2 mm), which enhances after contrast administration, is considered to represent ongoing inflammation of the synovial membrane because it has been shown to be responsive to treatment [8, 9]
When clinical assessment shows no signs of inflammation but synovial thickening is observed on MRI, it is commonly interpreted as subclinical synovitis

Summary

Introduction

Juvenile idiopathic arthritis (JIA) is the most common cause of chronic joint inflammation in childhood and represents one of the leading causes of pediatric acquired disability [1] It encompasses a heterogeneous group of diseases in which clinical presentation, disease course and clinical outcome vary. In JIA, the general aim is to improve long-term outcome by early detection and treatment of disease activity and to identify children who are at risk for joint destruction and poor functional outcome [2, 3]. Synovial thickening detected on magnetic resonance imaging (MRI) is present in a significant number of children with clinically inactive juvenile idiopathic arthritis (JIA). Objective To evaluate patient characteristics and disease activity parameters in a cohort of children with clinically inactive JIA, both with and without synovial thickening, in order to clarify the observed discrepancy between clinical and MRI assessments. We compared patient characteristics and disease activity parameters between the groups

Methods

Results

Discussion

Conclusion