Distribution pattern of MRI abnormalities within the knee and wrist of juvenile idiopathic arthritis patients: signature of disease activity.
OBJECTIVE
The aim of this study in clinically active juvenile idiopathic arthritis (JIA) was to assess the frequency and distribution pattern of synovitis as hallmark of disease and additional soft-tissue and bony abnormalities on MRI in the knee and wrist as two target joints.


METHODS
MRI datasets of 153 clinically active JIA patients (110 with knee and 43 with wrist involvement) were evaluated independently by two readers for the presence of literature-based imaging features: "synovial hypertrophy," "bone marrow changes," "bone erosions," "tenosynovitis" (only in the wrist), and "cartilage lesions" (only in the knee) in accordance with validated definitions and scoring locations.


RESULTS
Synovial hypertrophy was most frequently observed--both in the knee and in the wrist (61.8-65.1% of cases). For the knee, the most frequently involved locations were the cruciate ligaments (46/183 locations [25.1%] affected with synovial hypertrophy) and medial patella (18/62 locations [29.0%] with bone marrow changes). Cartilage lesions and bone erosions were rare (5.5-7.3% of cases). For the wrist, most frequently involved were the radiocarpal joint (21/64 locations [32.8%] with synovial hypertrophy), lunate (7/46 locations [15.2%] with bone marrow changes), and capitate or triquetrum (6/28 locations [21.4%] with bone erosions). Tenosynovitis was a common wrist-specific feature (46.5% of cases). MRI showed no abnormalities in a subgroup of patients with clinically active knee (23.6%) and wrist (16.3%) involvement.


CONCLUSIONS
The distribution pattern of MRI abnormalities in the knee and wrist of active JIA patients provides a practical tool to detect a signature of JIA disease activity in target joints.
1 Department of Radiology (G1-215), Academic Medical Center, University of Amsterdam, Meibergdreef 9, 1105AZ Amsterdam, The Netherlands.
Charlotte M
CM
Nusman
Robert
R
Hemke
Dieneke
D
Schonenberg
Koert M
KM
Dolman
Marion A J
MA
van Rossum
J Merlijn
JM
van den Berg
Taco W
TW
Kuijpers
Mario
M
Maas
D000293:Adolescent; D001171:Arthritis, Juvenile / Q000473:pathology*; D002648:Child; D005260:Female; D006801:Humans; D007719:Knee Joint / Q000473:pathology*; D008279:Magnetic Resonance Imaging; D008297:Male; D014955:Wrist Joint / Q000473:pathology*