Imaging the Earliest Signs of Rheumatoid Arthritis

Magnetic resonance imaging (MRI) and ultrasound (US) can image joint inflammation and damage in rheumatoid arthritis (RA) earlier and more clearly than X-rays, but the largest MRI study to date suggests it can even detect subclinical joint inflammation in patients with clinically suspect arthralgia (CSA), a possible precursor to RA.¹

The study, from the Leiden University Medical Center in the Netherlands, imaged 102 patients with and without clinical arthritis, most of them in their 40s, using MRI. Among the 93 who had CSA, 44% showed signs of inflammation.

Among those patients, 35% (n=10) progressed to clinical arthritis within the four months that followed.¹ Eight were diagnosed with RA, and one each with unspecified arthritis and psoriatic arthritis.

The researchers scored synovitis, tenosynovitis, and bone marrow edema according to the Outcome Measures in Rheumatology Clinical Trials (OMERACT) rheumatoid arthritis MRI scoring system (RAMRIS), after imaging patients with suspected CSA using unilateral MRI of metacarpal (MCP) joints 2-4, wrist, and metatarsal (MTP) joints 1-5. They considered a sum of three or greater of these conditions to be positive for inflammation. Among the CSA patients who progressed to clinical arthritis, the median combined inflammation score was 4.¹

They say the clinical characteristics they studied could not have distinguished clearly between the CSA patients who showed joint inflammation on MRI and those who didn't.

MRI is also used to detect osteitis, inflammation that affects the bone, which also predicts progression of undifferentiated arthritis to RA. The bone erosion in RA results from a combination of osteitis, synovitis, and bone resorption.

Other researchers have found indications that severe synovitis may indicate the bone erosion that produces the crippling damage of RA.² The second of these reports, a small study from Nagasaki University in Japan, reveals that synovitis seen on joints in the hand and wrist by ultrasound correlates with osteitis documented by MRI in those same joints -- and is predictive of bone erosion.²

The team used grey scale (GS) and power Doppler (PD) US to image the hands of 30 patients who fulfilled the 2010 American College of Rheumatology (ACR) classification criteria for RA and who had not yet taken disease-modifying anti-rheumatic drugs (DMARDs), including biologics and glucocorticoids.

The researchers evaluated images of the of articular synovitis and bone erosion in the both wrist and MCP joints using the method proposed by the European League Against Rheumatism (EULAR). When MRI detected osteitis of the identical sites, they also evaluated the affected joints within 3 days using the RA MRI scoring system (RAMRIS).

MRI-proven osteitis appeared in 8.3% of MCP joints and 48.3% of wrist joints, with increased prevalence in the joints where the GS or PD grade of articular synovitis was greater, at 2 or 3.² There is a clear correlation, the authors conclude, between synovitis on ultrasound, osteitis on MRI, and bone erosion.

References:

1.   van Steenbergen HW, van Nies JA, Huizinga TW, et al, Characterising arthralgia in the preclinical phase of rheumatoid arthritis using MRI. Ann Rheum Dis. (2014) Apr 9; 10.136/annrheumdis-2014-205522.  (E-pub ahead of print).
2.   Kawashiri SY, Suzuki T, Nakashima Y, et al., Synovial inflammation assessed by ultrasonography correlates with MRI-proven osteitis in patients with rheumatoid arthritis. Rheumatology (Oxford). (2014) Mar 22. [Epub ahead of print].