The value of sonography in the detection of bone erosions in patients withrheumatoid arthritis - A comparison with conventional radiography

Objective. The ability to make an early, accurate diagnosis of rheumatoid a rthritis (RA) has become increasingly important with the availability of ne w, expensive, and targeted therapies. However, plain radiography, the tradi tional method of detecting the characteristic bone erosions and an importan t adjunct in establishing a diagnosis of RA, is known to be insensitive,Thi s study compared sonography, a modern imaging technique, with conventional radiography for the detection of erosions in the metacarpophalangeal (MCP) joints of patients with RA. Methods. One hundred RA patients (including 40 with early disease) underwen t posteroanterior radiography and sonography of the MCP joints of the domin ant hand. Twenty asymptomatic control subjects also underwent sonography, E rosion sites were recorded and subsequently compared using each modality. M agnetic resonance imaging (MRI) was performed on the second MCP joint in 25 patients with early RA to confirm the pathologic specificity of sonographi c erosions. Intraobserver reliability of sonography readings was assessed u sing video recordings of 55 MCP joint scans of RA patients, and interobserv er reliability was assessed by comparing 160 MCP joint scans performed sequ entially by 2 independent observers. Results. Sonography detected 127 definite erosions in 56 of 100 RA patients , compared with radiographic detection of 32 erosions (26 [81%] of which co incided with sonographic erosions) in 17 of 100 patients (P < 0.0001), In e arly disease, sonography detected 6.5-fold more erosions than did radiograp hy, in 7.5-fold the number of patients. In late disease, these differences were 3.4-fold and 2.7-fold, respectively. On MRL, all sonographic erosions not visible on radiography (n = 12) corresponded by site to MRI abnormaliti es. The Cohen-kappa values for intra- and interobserver reliability of sono graphy were 0.75 and 0.76, respectively. Conclusion. Sonography is a reliable technique that detects more erosions t han radiography, especially in early Ri, Sonographic erosions not seen on r adiography corresponded to MRI bone abnormalities, This technology has pote ntial in the management of patients,with early RA/inflammatory arthritis an d is likely to have major implications for the future practice of rheumatol ogy.