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MRI appears to be a sensitive way to follow structural damage in patients with rheumatoid arthritis (RA), with significant advantages over conventional radiography and ultrasound, physicians in California report. NEW YORK (Reuters Health) - MRI appears to be a sensitive way to follow structural damage in patients with rheumatoid arthritis (RA), with significant advantages over conventional radiography and ultrasound, physicians in California report. This means of visualization may also be feasible and cost-effective for an individual practice, with the advent of portable in-office scanners.

According to co-author Dr. John V. Crues III, from Radnet Management in Los Angeles, and associates, better and more frequent imaging studies may detect and monitor bony erosions early in the course of the disease, when more advanced damage can be prevented by early treatment.

MRI examinations were performed using a portable high-resolution scanner (Applause, GE Medical Systems). As the investigators note in the October issue of the Journal of Rheumatology, it requires no magnetic shielding, can be plugged into an ordinary 110 V AC wall adaptor, and is portable when mounted on wheels.

The investigators used the scanner to visualize the second and third metacarpophalangeal joints and wrists. Images were compared with those obtained by standard posteroanterior, lateral, and oblique radiography of the hands and wrist.

One hundred fifty-six patients underwent at least two MRIs, an average of 8 weeks apart. The radiologists observed changes in 50% of follow-up MRI exams, including increased number or size of erosions in 30%, a decrease in size or number in 15%, and a combination of the two in 4%.

The authors followed 632 individual erosions. Increases in size were observed in 14%, decreases in 8%, and both increases and decreases in less than 1%.

In contrast, only one radiographic image follow-up out of 165 revealed a new erosion, and one showed increased size in another.

Dr. Crues and his associates point out that ultrasound may reveal erosions and demonstrate pannus formation, but cannot identify changes in bone marrow. Computed tomography, on the other hand, demonstrates erosions accurately but falls short in its ability to evaluate periarticular soft tissues and bone marrow. High-resolution, multidetector CT is not portable and exposes patients to ionizing radiation.

And although MRI is expensive, it may be cost-effective when considering the costs of disability and advanced treatment, including cytokine blockers, if erosions are not detected early in the course of rheumatic arthritis.

"For these reasons, MRI is the most promising modality for evaluating bony erosive disease," the investigators conclude.

J Rheumatol 2006:33:1957-1967.