DESTIN, FLA. — The advent of disease-modifying drugs has made magnetic resonance imaging an indispensable tool for diagnosing and monitoring patients with rheumatoid arthritis, Charles G. Peterfy, M.D., said at a rheumatology meeting sponsored by Virginia Commonwealth University.
MRI already is the tool of choice for use in clinical trials. Now it's time for clinical practice to incorporate this superior technology, said Dr. Peterfy, a radiologist specializing in musculoskeletal imaging, and chief medical officer of Synarc Inc., which specializes in radiology services for clinical trials. Radiographs have a number of shortcomings. Not only are they relatively insensitive for predicting disease progression and bone erosion, they are not accurate for measuring cartilage loss or for visualizing the synovium.
MRI can provide information on synovitis, tendonitis, and bone edema (or osteitis), all of which improve the predictive accuracy, particularly the negative predictive value. “The absence of these findings on MRI is a very powerful predictor that this patient is not going to progress,” Dr. Peterfy said at the meeting, also sponsored by the International Society for Clinical Densitometry.
MRI of synovitis correlates with histopathology, Doppler ultrasound, PET imaging and “has been found to be more sensitive than clinical examination for swelling and tenderness,” he said.
There are MRI techniques that allow the visualization of preerosive osteitis, which is key because osteitis can progress very rapidly, said Dr. Peterfy, who also is on the advisory board for MagneVu, the maker of portable MRI units. According to one study, baseline osteitis can predict functional disability at 6 years. A number of studies have demonstrated that MRI detects erosions earlier than x-rays, said Dr. Peterfy. In fact, one study demonstrated the ability of baseline MRI to predict bone erosions as much as 2 years later.
The development of a semiquantitative scoring system—such as the Rheumatoid Arthritis MRI Score (RAMRIS) developed by the European League Against Rheumatism-Outcome Measures in Rheumatoid Arthritis Clinical Trials (EULAR-OMERACT)—should help standardize the use of MRI to monitor the progression of RA. This system incorporates erosions, osteitis, and synovitis to assess disease changes. The group recently published an MRI atlas intended to improve the performance and generalizability of the MRI scoring system (Ann. Rheum. Dis. 2005;64 [suppl. 1]:i3-i55).