Early diagnosis of juvenile idiopathic arthritis (JIA) facilitates earlier more aggressive therapy, and improved outcome. Recognition of the features of early, untreated JIA on magnetic resonance imaging (MRI) will improve disease detection and expedite treatment. This study aims to highlight the relevant MRI features.
MRI examinations of the knee joint were performed on 11 children with clinically confirmed, early, untreated JIA. The MRI images were obtained at a mean of 2 months after symptom onset and independently evaluated by two consultant paediatric radiologists.
Abnormalities were found on all MRI examinations. Synovial hypertrophy, joint effusions, popliteal lymph nodes and soft tissue swelling were present in all patients. Gadolinium DTPA enhancement improved the detection of synovial hyperplasia. Metaphyseal splaying and condylar overgrowth were seen in five cases (41%), oedema of the lateral collateral ligament in two cases (18%) and superficial cartilage thinning in one case. Bony erosions and deep cartilage destruction were not demonstrated.
MRI of the knee joint identifies early joint changes which are distinct from those in later disease. The presence of these features should alert the radiologist to the possible diagnosis of JIA and post gadolinium DTPA sequences should be performed. Gadolinium DPTA enhancement increases the sensitivity for the detection of inflammatory changes in JIA.