medwireNews: In clinically suspect arthralgia (CSA), erosion detected by magnetic resonance imaging (MRI) in the small bones of the hands and feet does not generally correspond with radiographic erosive disease or local radiographic progression, show the results of a longitudinal imaging study.
Therefore, “MRI-detected erosions in CSA should be regarded with caution to avoid overinterpretation,” suggest Quirine Dumoulin (Leiden University Medical Center, the Netherlands) and fellow study investigators in Rheumatology.
Of the 405 people (mean age 45 years, 76% women) with CSA included in the study, 190 (47%) had MRI-detected erosions in the hands or feet at 2 years’ follow-up. By comparison, 62 (15%) had evidence of radiographic erosions.
While bones with an MRI-detected erosion were significantly more likely than those without to also have a local radiographic-detected erosion (odds ratio [OR]=5.23), the researchers note that radiographic erosions were present in just 3.5% of the 341 bone locations where an MRI-detected erosion was detected.
“As it can be expected that MRIs of the small joints will be increasingly used, it is relevant to comprehend the value of MRI-erosions in CSA-patients,” Dumoulin et al explain.
Between April 2012 and May 2021, the team consecutively recruited people from the Leiden CSA cohort who had recent (<1 year) onset of arthralgia in the small joints that a rheumatologist considered at risk of progression to rheumatoid arthritis (RA).
Bilateral radiography of the hands and feet was performed at enrolment and repeated at 12 and 24 months’ follow-up, or if inflammatory arthritis developed. A Sharp-van-der-Heijde score (SHS) of 1 point or above was used to denote the presence of a radiographic erosion, with at least a 1-point change in SHS used to denote progression.
Unilateral contrast-enhanced 1.5T MRI of the wrist, 2nd–5th metacarpophalangeal (MCP) and 1st-5th metatarsophalangeal (MTP) joints was conducted within 2 weeks of the inclusion visit. This was performed on the most painful or dominant side.
Two independent readers, blinded to the clinical data, scored the MRIs for erosions and subclinical inflammation (synovitis, tenosynovitis, and osteitis). An MRI erosion was defined as being present if the RA MRI score (RAMRIS) for erosion was 1 point or above, which indicated that 1–10% of the bone was eroded. Subclinical inflammation was defined as a mean RAMRIS score of at least 1 point in the equivalent joint, tendon sheath, or bone to that of the MRI-detected erosion.
“MRI-erosions were more prevalent than radiographic erosions,” say the researchers. Of the 9277 bones studied, an MRI-detected erosion was seen in 341 (3.7%), whereas a radiographic erosion was detected in 73 (0.8%).
They note that most MRI-detected erosions occurred in the proximal bones of the wrist (MCP-2 and MCP-3) and foot (MTP-1 and MTP-5), which “have previously been described as RA-specific.”
The presence of subclinical inflammation in the area local to the MRI-detected erosion strengthened the association between erosions being seen on both MRI and radiography, says the team, upping the OR to 6.29.
As for local radiographic progression, this only occurred in 35 (0.4%) of the studied bone locations. The researchers say that the presence of MRI erosions at baseline was not predictive of radiographic progression. Testing positive for anti-citrullinated protein antibody, which was present in 13% of the study population, did not affect the findings.
“This finding underlines for the clinician that an MRI-detected erosion on its own is not reason enough to suspect imminent RA,” suggests the team.
Larger cohort studies with longer follow-up are advisable, the researchers acknowledge. They conclude that, in most cases, MRI-detected erosions do not equate to radiographic disease.
“Therefore, treatment decisions should not be guided solely by the finding of MRI-detected erosions and overinterpretation should be avoided,” the researchers say.
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