An anatomical explanation for good-prognosis rheumatoid arthritis

Abstract

Although most patients with rheumatoid arthritis (RA) have persistent progressive disease there is a heterogeneity of outcome in early disease. An acute presentation of disease is one of the best predictors of a good outcome. On the basis of magnetic resonance imaging (MRI) studies, it has been suggested that there are two types of inflammatory joint disease, one with an intrasynovial location with a poor prognosis and one with an extrasynovial location which generally has a good prognosis. We wondered whether the good prognosis subset of RA was due to a different primary location of pathology. Untreated patients with RA were selected at presentation to the early arthritis clinic to represent the extremes of acute onset good-prognosis RA (GPRA) or insidious onset poor-prognosis RA (PPRA). 30 patients who fulfilled the American College of Rheumatology criteria for RA and 30 controls were studied by imaging; the latter group did not receive gaddiniumdiethylenetriamine penta-acetic acid contrast. RA patients were selected on the basis of their clinical presentation—22 patients with PPRA and eight patients with GPRA (onset of 24 h). MRI was done with a 1·5 T Gyroscan ACS NT (Philips Medical Systems) within 1 week of presentation to the clinic (table) with image acquisition by a surface coil. The clinicians responsible for patients’ care were unaware of the MRI findings at clinical follow-up. Coronal T1weighted spin echo coronal pulse sequences, T2-weighted turbo spin echo SPIR coronal pulse sequences (T2 fat suppressed), a single 10 mm thick single Spoiled Gradient Echo dynamic subtraction gadolinium-DTPA sequence, and a T1 SE post gadolinium-DTPA sequences of metacarpophalangeal joints 2–5 of the dominant hand were done. Films were scored under masked conditions independently by two musculoskeletal radiologists with consensus opinion in the event of disagreement. Soft tissue inflammation was scored as synovial where maximum in the