Maximum intensity projection as a tool to diagnose early rheumatoid arthritis.

In this study, we investigated the usefulness of contrast-enhanced MRI with maximum intensity projection (MIP) as a convenient tool for detecting early rheumatoid arthritis (RA). A total of 21 patients with undiagnosed arthritis of the hands at the initial visit were enrolled in a prospective study over a 1-year period. The number of swollen joints found during physical examination at this first visit, the results of serological tests and the number of synovitis joints diagnosed on MIP images were compared between the RA group and non-RA group. Of the 21 patients, 17 (81%) from the initial study who were followed up for an additional 1 year entered this study. Of these, 5 met the conditions for diagnosis of RA during follow-up, and 12 did not. MIP images were used to review the arthritis of RA patients, and a significant difference was found in the number of synovitis inflammations detected with MIP images when compared with findings after physical examinations. The two criteria of positive CARF and/or anti-CCP antibody and symmetrical synovitis in bilateral hands on MIP images allowed the prediction of RA with 100% sensitivity and 75% specificity. Thus, MIP is a useful tool for making early diagnosis of RA because it yields clear visualization even with just one image.