Robert Hemke, Presenter: Nothing to Disclose

Marion van Rossum MD,PhD, Abstract Co-Author: Nothing to Disclose

Janneke Annink, Abstract Co-Author: Nothing to Disclose

Mira van Veenendaal, Abstract Co-Author: Nothing to Disclose

Taco Kuijpers MD,PhD, Abstract Co-Author: Nothing to Disclose

Mario Maas MD, Abstract Co-Author: Nothing to Disclose

To determine the MRI findings in the knee in JIA by using a newly developed literature-based Juvenile Arthritis MRI Scoring System (JAMRIS).

In this prospective cohort study both knees of 29 children (mean age 12 years [range 6-17]) were examined using an open-bore MRI (1.0T).Clinical indications for MRI were: clinical arthritis in ≥ 2 joints or > 6 weeks suggestive for JIA. All patients had a rheumatologic work-up including the ACR-Pedi core-set and bilateral X-rays of the target joints. patients with various clinical activities were included. Imaging protocol consisted of T1, T2 and T2-fatsat sequences in all three anatomical directions. No intravenous contrast was used.  A literature-based MR scoring system was constructed, focused on structural damage, anatomical location of pathology and signal intensity changes. One reader evaluated all studies, blinded to clinical status.   

The examinations were successfully completed by all 29 patients. Synovial hypertrophy was seen in 12 (21%) of the 58 knees. Hydrops of the suprapatellar bursa was seen in 37 (64%) effusion in the lateral recess was seen in 15 (26%), Baker’s cyst in 9 (15%) and effusion anterior to the anterior cruciate ligament (ACL) was seen in 41 (71%) of the 58 knees. Erosions were seen in 3 (5%), subcortical bone marrow edema in 18 (31%) and epiphyseal bone marrow edema in 18 (31%) of the 58 knees. Cartilage lesions were seen in 8 (14%) knees and tendinopathy / internal derangement in 5 (9%) knees. Abnormalities of the infrapatellar fat pad were seen in 44 (76%) of the knees and popliteal lymph nodes in 37 (64%) of the 58 knees.

Effusion anterior to the ACL is a new and common phenomenon observed upon MR imaging of one of the major target joints in JIA patients. Hydrops in the bursa suprapatellaris, abnormalities of the infrapatellar fat pad and popliteal lymph nodes are also common MR findings. Bone erosions and tendinopathy/internal derangement were infrequent. Soft tissue abnormalities were not seen and hence removed from our scoring list.

The new JAMRIS scoring system enables to identify the most common changes in the knee caused by JIA. Correlation with clinical assessment is necessary.

Hemke, R, Rossum, M, Annink, J, Veenendaal, M, Kuijpers, T, Maas, M, MRI Findings in the Knee in Children with Juvenile Idiopathic Arthritis (JIA): Experience with a Newly Developed Juvenile Arthritis MRI Scoring System (JAMRIS).  Radiological Society of North America 2009 Scientific Assembly and Annual Meeting, November 29 - December 4, 2009 ,Chicago IL. http://archive.rsna.org/2009/8001368.html