As the trend to diagnose and control rheumatoid arthritis in the early stages gains ground with rheumatologists, gadolinium-enhanced MRI of RA can play a vital role in an aggressive treatment process, according to a study in the August 2000 issue of Radiology.
A multidisciplinary team from Jichi Medical School in Tochigi-ken, Japan conducted a prospective study to assess the effectiveness of MRI for diagnosing early-stage rheumatoid arthritis (RA) and found that it was particularly helpful in helping other clinicians separate RA from other conditions with joint manifestations.
The study population consisted of 50 patients, ranging in age from 19 to 74 years, who presented with persistent pain in three or more joint areas. X-rays could not confirm their polyarthralgia was RA (Radiology, August 2000, Vol. 216:2, pp.569-575).
MR scans were performed on a 1.5-tesla superconducting magnet equipped with a circular surface coil 20 cm in diameter (MRT 200 FX/II, Toshiba, Tokyo). Multiple coronal images of the hands were obtained by using a fat-suppressed, T1-weighted spin-echo sequence. Contrast-enhanced images were obtained after bolus injection of 0.1 mmol/kg gadopentetate dimeglumine (Magnevist, Schering, Berlin).
Based on the results, 27 patients were classified as having RA and 21 were diagnosed with non-RA conditions such as osteoarthritis, reactive arthritis, or arthritis related to a viral condition. MR showed a sensitivity of 96%, a specificity of 86%, and an accuracy of 94%. In the three false positives, the patients were reassessed as having cryoglobulinemia, osteoarthritis, and transient arthritis related to a virus.
In comparison, clinical and radiographic follow-up found RA in 26 patients, and other joint diseases in 22 patients. Traditional x-rays had a sensitivity of 69%, a specificity of 96%, and accuracy of 81%. RA diagnosis based on the American Rheumatism Association (ARA) classification criteria yielded a sensitivity of 77%, a specificity of 91%, and an accuracy of 74%.
"As compared with the diagnostic performance achieved with the traditional [x-ray] format…use of the MR imaging criterion revealed [13] additional patients with true RA," the authors wrote. "In six patients with false-negative results based on the [ARA] classification tree, the correct diagnosis of RA was established by using the MR imaging."
Although RA is a systemic disease, the authors said they chose to focus on the joints in the hands because they are the earliest and most often affected areas.
By Shalmali Pal
AuntMinnie.com staff writer
August 23, 2000
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