The use of magnetic resonance imaging (MRI)-detected inflammation and joint damage in the diagnosis of rheumatoid arthritis is recommended by a European League Against Rheumatism imaging task force. This recommendation is based on the sensitivity of MRI and not on specificity. Knowledge of the prevalence of MRI-detected features in symptom-free persons, however, is pivotal when considering MRI for diagnostic purposes.
From November 2013 to December 2014, 196 symptom-free persons of different ages were recruited from the general population. Inclusion criteria were no history of inflammatory arthritis, no joint symptoms during the previous month, and no clinically detectable arthritis on physical examination. Contrast-enhanced MRIs of the dominant metacarpophalangeal (MCP), wrist, and metatarsophalangeal (MTP) joints were obtained using a 1.5T scanner and scored by 2 readers for synovitis, bone marrow edema, tenosynovitis, and erosions. For analyses at the joint level, MRI-detected inflammation was considered present if both readers scored the image as positive.
Of 193 persons scanned (ages 19-89 years), only 28% had no single inflammatory feature and 22% had no erosions. Primarily low-grade features were observed. All MRI features were positively correlated with age (P < 0.001). Preferential locations for synovitis were MCP2, MCP3, the wrists, and MTP1. Bone marrow edema was frequently present in MCP3, the scaphoid, and MTP1. Tenosynovitis was infrequent, except for in the extensor carpi ulnaris. Preferential locations for erosions were MCP2, MCP3, MCP5, the distal ulna, MTP1, and MTP5. Tables with age-, location-, and inflammation type-dependent frequencies were constructed. Simultaneous colocalized presence of synovitis, bone marrow edema, tenosynovitis, or erosions occurred.
MRI-detected inflammation and erosions are prevalent in symptom-free persons from the general population, especially at older ages and at preferential locations.