THU0318 A prospective comparative study of three methods of assessment of the knee joint in juvenile idiopathic arthritis: Clinical examination, ultrasound and MRI. (a newly developed knee mri scoring system)

Abstract

Background Juvenile Idiopathic Arthritis (JIA) is the main cause of chronic arthritis in children, and it can lead to joint damage and disability. Detecting early articular involvement in JIA is therefore of crucial importance to prevent cartilage and bone damage in these young patients. Since 2004 we have undertaken a prospective study of children with newly diagnosed JIA with knee involvement, and we noted that, not infrequently, knees deemed clinically normal had appreciable effusion on ultrasound (US). Objectives We wished to prospectively compare agreement between clinical, US and MRI assessments of the knee joints in children with JIA, and to develop an MRI scoring system that allows assessment of disease activity and progression in children with JIA and compare it with US examination. Methods Three hundred and thirty one knees from 48 children, affected by JIA with knee arthritis, were assessed clinically and ultrasonographically on the same day, using a semi-quantitative scoring system from 0 to 3 for swelling and effusion, respectively. A subgroup of these children (25) with a total of 40 knees had matching MRI scans obtained within 0 to 14 days from clinical and US examinations. For those, US and MRI scans (T2 weighted images) were scored 0-3 for effusion, synovial hypertrophy, bone oedema and bone erosions, using our newly developed knee MRI scoring system. An open 0.2 Tesla scanner without administration of gadolinium was used. Results A moderate agreement for effusion was found between the 331 knees assessed clinically and ultrasonographically (K 0.54). Out of the 260 knees without swelling, 30 (11.5%) had mild to moderate effusion on US (Table). In the subgroup of 40 knees that had matching US and MRI scans it was demonstrated a good agreement for effusion (K 0.66) and a moderate agreement for synovial hypertrophy (K 0.47) between the two methods of assessments. The inter-observer reliability for US was very good for effusion (K 0.87), and good for synovial hypertrophy (K 0.68). The intra-observer reliability for MRI was good for effusion (K 0.73) and very good for synovial hypertrophy (K 0.85). Moreover, US tends to be more sensitive than MRI at detecting joint effusion (US scored on average 0.08 higher on the scoring system than MRI), maybe due to the lower sensitivity of MRI as T2 weighted images rather than contrast with gadolinium was used. Conclusions A significant number of knee joint effusions are missed on clinical examination. Therefore US of this joint should be used as an adjunct to clinical examination to avoid under-diagnosis, especially when joint injections are being considered, when clinical examination is negative and symptoms are equivocal for active arthritis, at follow-up to assess treatment’s efficacy. We have developed a reproducible scoring system for MRI of the knee. US appeared to be more sensitive than MRI at detecting effusions, however this is probably due to the absence of using gadolinium in MRI. It does however highlight the benefits of MSUS in paediatric rheumatol...

Diagnostic Utility of Ultrasound Versus Physical Examination in Assessing Knee Effusions

“…Only one study on this topic was found in the literature review and was presented in conference abstract form. 36 Additional study is also needed about what size effusion should change clinical management. Previous studies have shown that ultrasound and MRI can detect knee effusions of 1-4 mL.…”

EULAR-PReS points to consider for the use of imaging in the diagnosis and management of juvenile idiopathic arthritis in clinical practice

“…Several studies compared US with MRI in the detection of inflammation, particularly at the knee 13 14 33 34. These studies have shown MRI to be better in detecting knee inflammation than US (mean detection rate 1.20-fold, range 0.63–1.56-fold) and in particular MRI was better than US in differentiating pannus from effusion 13.…”

Diagnostic Accuracy Study of the Pediatric‐Specific Ultrasound Scoring System for the Knee Joint in Children With Juvenile Idiopathic Arthritis

“…Prior studies have evaluated the performance of the MSUS against physical examination, laboratory markers of inflammation, or both [33][34][35] as well as agreement between clinical, US, and MRI assessments in the knee joints of children. 36 However, inference of the validity of the MSUS for JIA based on these studies is problematic. These prior studies did not use 1) validated US definitions of synovitis and its elementary components, [37][38][39] nor did they use 2) standardized and reliable acquisition imaging protocols and scoring systems for the MSUS.…”

“…In JIA, studies that support the validity of the MSUS as an imaging biomarker are scarce. Prior studies have evaluated the performance of the MSUS against physical examination, laboratory markers of inflammation, or both 33–35 as well as agreement between clinical, US, and MRI assessments in the knee joints of children 36 . However, inference of the validity of the MSUS for JIA based on these studies is problematic.…”