Evidence for a different anatomic basis for joint disease localization in polymyalgia rheumatica in comparison with rheumatoid arthritis

Abstract

Objective. The anatomic basis for joint disease localization in polymyalgia rheumatica (PMR) is poorly understood. This study used contrast-enhanced and fat suppression magnetic resonance imaging (MRI) to evaluate the relationship between synovial and extracapsular inflammation in PMR and early rheumatoid arthritis (RA).Methods. Ten patients with new-onset PMR and 10 patients with early RA underwent dynamic contrastenhanced MRI and conventional MRI of affected metacarpophalangeal (MCP) joints. Synovitis and tenosynovitis were calculated based on the number of enhancing voxels, initial rate of enhancement, and maximal enhancement of gadolinium diethylenetriaminepentaacetic acid (Gd-DTPA). Periarticular bone erosion and bone edema were scored according to the OMERACT (Outcome Measures in Rheumatology Clinical Trials) scoring system in both groups. The degree of extracapsular Gd-DTPA enhancement was assessed in both conditions using semiquantitative scoring.Results. No significant differences were seen in the volume of synovitis (P ‫؍‬ 0.294), degree of flexor tenosynovitis (P ‫؍‬ 0.532), periarticular erosions (P ‫؍‬ 0.579), or degree of bone edema (P ‫؍‬ 0.143) between RA and PMR joints. However, despite comparable degrees of synovitis, the proportion of MCP joints showing extracapsular enhancement was higher in the PMR group (100%) than in the RA group (50%) (P ‫؍‬ 0.030). One PMR patient, but none of the RA patients, had bone edema at the capsular insertion.Conclusion. Despite degrees of synovitis and tenosynovitis comparable with those in RA, PMR-related hand disease is associated with prominent extracapsular changes, suggesting that inflammation in these tissues is more prominent than joint synovitis, which is common in both conditions. This suggests that the anatomic basis for joint disease localization differs between RA and PMR.

Magnetic resonance imaging in the assessment of metacarpophalangeal joint disease in early psoriatic and rheumatoid arthritis

“…Other studies have also reported on MRI erosions occurring more commonly in RA than PsA (23). However, we have noted that MRI erosions were as common in polymyalgia rheumatica (PMR)-related small joint synovitis as RA (24). Further research with longitudinal cohorts is needed to establish the true diagnostic and prognostic value of these findings.…”

Perspectives and unmet needs in polymyalgia rheumatica. Providing the fundamental framework for the development of new treatment regimes in polymyalgia rheumatica

“…The spatial resolution of fluorine-18-fluorodeoxyglucose (FDG) PET/CT studies and the short timespan between the PET and CT imaging does not always allow rigorous co-localization of FDG uptake and anatomical structures. However, periarticular uptake patterns in shoulders and hips of PMR patients (Figure 2), different from uptake patterns in RA patients, has been described and could reflect the extracapsular pattern found in MR studies (47,51,52). The pelvic girdle also shows localized FDG uptake adjacent to greater trochanter, ischial tuberosity, in front of hip joint/pectineus muscle and at ventral edges of the pubic bone reflecting either bursitis or enthesitis (47,52).…”

Polymyalgia rheumatica

“…Ultralyd og MR undersøkelser kan vise bursitter i naer relasjon til de store ledd (22). Ved MR-undersøkelse av perifere ledd er det gjort funn som tyder på at PMR har en annen type leddaffeksjon enn RA (23). Akuttfaseparametrene er forhøyet med forhøyet SR og CRP hos de aller fleste, og ofte er det lette utfall i leverfunksjonsprøvene.…”