LOS ANGELES, California, and ODENSE, Denmark—Magnetic resonance imaging (MRI) is more accurate than conventional radiography for monitoring response to rheumatoid arthritis (RA) therapy and for predicting which patients with early RA are likely to have disease progression despite methotrexate (MTX) treatment, according to new pilot studies from two research groups. Both used small, portable, in-office MRI equipment to image joints in the wrists and hands, and both research groups urge prompt validation of this approach in larger clinical trials.^1,2

These studies call into question some current treatment guidelines. "Current recommendations that patients should be followed with periodic radiographs should be reconsidered, since radiographic detection of erosions will not occur until significant damage has occurred, precluding the benefits of early treatment," write Timothy S. Chen, MD, and colleagues in The Journal of Rheumatology.¹

MRI More Sensitive Than X-ray for Seeing Changes in Bone Erosions

Timothy S. Chen, MD, and colleagues at Radnet Management in Los Angeles, California, report that high-resolution, in-office MRI (using the Applause^R 0.2 Tesla portable scanner) with an average follow-up time of 8 months in 246 patients with inflammatory arthritis detected changes in bony erosions in 124 (50%) patients, whereas follow-up with conventional radiography detected in only one of 165 patients (0.8%). All of these patients were being treated with aggressive disease-modifying antirheumatic drugs (DMARDs).

"Our study was designed to compare the sensitivity of MR versus conventional radiography in detecting changes in sizes of erosions over a relatively short time frame, as detection of changes may be of value in guiding recently advanced pharmacotherapy," Dr. Chen writes.

The patients in this study had either rheumatoid or psoriatic arthritis. The study documented changes in the size and number of bone lesions involving the second and third metacarpophalangeal (MCP) joints and wrists, evaluated with in-office MRI vs radiographs. The researchers found no MRI-detectable changes in 50% of examinations, an increase in the size or number of erosions in 30%, a decrease in the size or number of erosions in 15% [Figure], and both increases and decreases in erosions in 4%.

Figure. Decrease in erosion size. A. A large erosion is seen involving the radial aspect of the left third MC head (arrow) on February 9, 2004. The patient wa started on a TNF-α inhibitor. B. After 9 months on the TNF-α inhibitor the erosion is significantly smaller (arrow) on November 3, 2004. Reprinted from Chen TS, et al. J Rheumatol 2006; August 1, 2006, Epub ahead of print. Used with permission of The Journal of Rheumatology.

 

"In-office, high-resolution MRI is significantly more sensitive in detecting changes in erosions in patients undergoing treatment for RA than projection radiography, supporting MRI as an effective tool for following bone injury in patients with RA treated with DMARD," the authors write. They note that considerable work remains to be done on validating and standardizing this approach, especially with small field-of-view, in-office scanners.

They add, "[W]ith the increased recognition of the association of structural bone damage with disability in patients with RA and the efficacy of methotrexate (MTX) and TNF-α [tumor necrosis factor- α] inhibitors in controlling the progression of bone injury, accurate measures of erosive disease have garnered increased interest."

RA Patients Without Baseline MRI Erosions Unlikely to Develop Irreversible Joint Damage in 1 Year

A related office-based study by H. M. Lindegaard, MD, and colleagues at Odense University Hospital, Odense, Denmark, showed that patients with early RA who had MRI-detectable erosions at baseline in the MCP or wrist bones were significantly more likely than patients who did not have such lesions to develop x-ray–detectable erosions within 1 year.²

All 24 patients in this study had joint symptoms for <1 year at baseline and were treated with MTX beginning at 75 mg/week and titrating to a maximum of 20 mg/week in increments of 2.5 mg/wk every 6 weeks. Patients were examined clinically every 6 weeks. Conventional radiography of hands and wrists and MRI of the dominant wrist and MCP joints were done at baseline, 6 months, and 12 months. MRI was done using a 0.2 Tesla Artoscan^R dedicated extremity, low-cost MRI unit and required about 45 minutes per patient.

At 1 year, x-ray progression of lesions was apparent in five of 24 patients, there were 15 new MRI erosions in eight patients, and one of the 21 baseline erosions was no longer visible.

"In bones with MRI erosions at baseline, the relative risk of having radiographic bone erosions by the 1-year follow-up was 12.1, compared with bones without baseline MRI erosions," the researchers report. They point out that x-ray "is not effective in identifying future 'nonprogressors'—that is, patients without increasing joint damage who may therefore not require maximally aggressive treatment" and suggest that, since only 15% of patients without baseline MRI erosions developed x-ray erosions after 1 year, this subgroup might be spared the costs and risk of "maximally aggressive treatment."

References

1. Chen TS, Crues JV, Ali M, Troum O. Magnetic resonance imaging is more sensitive than radiographs in detecting change in size of erosions in rheumatoid arthritis. J Rheumatol. August 1, 2006. [Epub ahead of print]
2. Lindegaard HM, Vallo J, Horslev-Petersen K, et al. Low-cost, low-field dedicated extremity magnetic resonance imaging in early rheumatoid arthritis: a 1-year follow-up study. Ann Rheum Dis. 2006; 65:1209-1212. [Epub ahead of print]