MADRID – A high percentage of patients with early arthritis have inflammation of the small joints that can be detected with MRI but not by physical examination.
Results of a cross-sectional study, presented by Dr. Annemarie Krabben at the annual European Congress of Rheumatology, found that 66% of wrist, 27% of metacarpophalangeal (MCP), and 13% of metatarsophalangeal (MTP) joints that were not clinically swollen showed signs of inflammation on MRI. However, inflammation on MRI was present in 92% of wrists, 86% of MCP, and 29% of MTP joints that were clinically swollen.
"You would expect that inflammation on MRI would be present in the clinically swollen joints, but we also saw inflammation in the non-swollen joints," explained Dr. Krabben of Leiden University Medical Center in the Netherlands.
Furthermore, "when you look at the joints with MRI-detected inflammation, a lot of these didn’t have clinical inflammation," she added.
©Leiden University Medical Center
MRI of the wrist shows subclinical inflammation in a patient with early arthritis symptoms.
Clinical joint swelling was absent but signs of bone marrow edema were detected on MRI in 60% of wrist, 53% of MCP, and 78% of MTP joints. If severe MRI-detected edema was considered, joint swelling was absent in 35%, 39%, and 58% of wrist, MCP, and MTP joints, respectively. Joints without clinical swelling showed signs of inflammation on MRI in 61% of wrist, 64% of MCP, and 77% of MTP joints.
The study involved patients with early arthritis who were part of the Leiden Early Arthritis Clinic cohort. This cohort was established in 1993 to detect and treat inflammatory disorders early in the disease state (Rheumatology [Oxford] 2011;50:93-100).
Upon entry into the cohort, patients underwent a physical examination that included 68 tender and 66 swollen joint counts and 1.5 Tesla MRI of the wrist, MCP, and MTP joints. The latter were used to determine the presence and extent of synovitis, bone marrow edema, and tenosynovitis.
In total, 1,790 small joints were examined in 179 patients who had a median duration of symptoms of 15 weeks. Overall, 30% of wrist, 15% of MCP, and 11% of MTP joints were swollen at physical examination and the majority also showed inflammation on MRI.
"There was a lot of subclinical inflammation, especially bone marrow edema, in the nonswollen joints," Dr. Krabben said. Bone marrow edema is linked to erosive disease progression, she observed and suggested that the next step is to see what happens to patients with subclinical inflammation at baseline, and whether this will eventually progress to erosive disease.
The study was supported by the Dutch Arthritis Foundation (Reumafonds), the Netherlands Organization for Health Research and Development, and the Center for Translational Molecular Medicine. Dr. Krabben has received research funding from Reumafonds.