Can ultrasound be useful in detection of inactive disease in patients affected by jia? An observational case-control study of 128 subjects

Background: Musculoskeletal Ultrasound (MSUS) is commonly used to detect synovial inflammation in adults affected by inflammatory rheumatisms. MSUS in children is nowadays still a challenge. For this reason MSUS in JIA is still seldom known and used by pediatric rheumatologists. Objectives: To study if grey scale (GSUS) and Power Doppler Ultrasound (PDUS) can better identify subclinical synovitis than physical examination and could be added to Wallace criteria of inactive disease (ID) to better identify JIA patients (pts) on Clinical Remission (CR). Methods: 100 consecutive pts with JIA (age 18mo-25yrs) according to ILAR classification, with ID according to Wallace criteria, and 28 healthy controls were submitted to the MSUS of 42 joints (MCPs, PIPs, wrists, elbows, shoulders, hips, knees, ankles and MTPs). MSUS was performed immediately after clinical evaluation, by 3 trained sonographers (ODL, VR, AS), blinded to clinical findings, who recorded synovial hyperplasia, joint effusion and PDUS. Apparatus used: GE Logiq P5 with an 8-12MHz linear probe and Esaote MyLab 70 with a 6-18MHz linear probe. Intraobserver and interobserver reproducibility of US was assessed. In each joint, synovial hyperplasia/joint effusion were graded as follows: 0=absent, 1=mild, 2=moderate and 3=marked. PDUS was graded as follows: 0=absent, 1=presence of single vessel dot, 2=presence of confluent vessel dots in less than half of the synovial area and 3=presence of confluent vessel dots in more than half of the synovial area. A joint with US synovitis was defined as a joint in which any of the 3 US abnormalities was detectable. PDUS was considered positive in the presence of vessel dots on PDUS images only out of growing cartilage and if it was not a bone nutrition vessel. The US examination technique as well as the definitions and scoring of US features were based on published guidelines provided by the OMERACT in adults. Results: MSUS revealed the presence of 1 or more alterations of the synovial structures (effusion, hyperplasia or positive PDUS) in 23 out of 100 pts who satisfied the clinical criteria of ID according to Wallace definition (23%). 9 pts (39% out of 23 active pts & 9% out of all 100 pts) have only one joint involved. The other 14 pts (61% out of 23 active pts & 14% out of all 100 pts) presented US activity in more than one joint. 43 of the 4200 examined joints were active at US (1,02%). In 17 of these 43 joints (39%) US revealed joint effusion, hyperplasia and PDUS. In 29 joints (67%) there were only two of these US features. No abnormalities were found in healthy controls. Conclusions: Our data confirm the usefulness of US in pediatric joint examination to identify active joints in JIA pts, to set up an appropriate treatment and to define inactive disease in a more accurate way than referring only to Wallace criteria. Further studies are needed to understand if these findings are related to a greater frequency of relapses.