Ultrasonography of the metacarpophalangeal and proximal interphalangeal joints in rheumatoid arthritis: a comparison with magnetic resonance imaging, conventional radiography and clinical examination

Abstract

Signs of inflammation and destruction in the finger joints are the principal features of rheumatoid arthritis (RA). There are few studies assessing the sensitivity and specificity of ultrasonography in detecting these signs. The objective of the present study was to investigate whether ultrasonography can provide information on signs of inflammation and destruction in RA finger joints that are not available with conventional radiography and clinical examination, and comparable to the information provided by magnetic resonance imaging (MRI). The second to fifth metacarpophalangeal and proximal interphalangeal joints of 40 RA patients and 20 control persons were assessed with ultrasonography, clinical examination, radiography and MRI. With MRI as the reference method, the sensitivity, specificity and accuracy of ultrasonography in detecting bone erosions in the finger joints were 0.59, 0.98 and 0.96, respectively; they were 0.42, 0.99 and 0.95 for radiography. The sensitivity, specificity and accuracy of ultrasonography, with signs of inflammation on T1-weighted MRI sequences as the reference method, were 0.70, 0.78 and 0.76, respectively; they were 0.40, 0.85 and 0.72 for the clinical examination. With MRI as the reference method, ultrasonography had higher sensitivity and accuracy in detecting signs of inflammation and destruction in RA finger joints than did clinical and radiographic examinations, without loss of specificity. This study shows that ultrasonography has the potential to improve assessment of patients with RA.

Figure 1

Signs of destruction on ultrasonography in the fourth proximal interphalangeal joint: early RA. MRI and conventional radiography revealed no signs of destruction in the joint. A bone erosion (arrow) is visualized with ultrasonography in (a) the longitudinal and (b) the transverse planes. MRI, magnetic resonance imaging; RA, rheumatoid arthritis.

Figure 2

Signs of destruction and inflammation on ultrasonography and MRI in second metacarpophalangeal joint: established RA. Thin arrows indicate an erosive change; thick arrows indicate synovitis. Ultrasonography in the (a) longitudinal and (b) the transverse planes shows both signs of destruction (grade 2) and inflammation (grade 3). Axial T1-weighted magnetic resonance images were obtained (c) before and (d) after contrast administration (grade 3 synovitis). Additionally, a coronal T1-weighted magnetic resonance image (e) before contrast administration visualizes the same bone erosion as shown in panels c and d. The coronal magnetic resonance image of the second metacarpophalangeal joint (panel e) is additionally covered by a grid illustrating division of the assessed joints into quadrants: proximal radial, proximal ulnar, distal radial and distal ulnar. MRI, magnetic resonance imaging; RA, rheumatoid arthritis.

Figure 3

Signs of synovitis on ultrasonography and MRI in fourth proximal interphalangeal joint: early RA. Arrows indicate an area with synovitis. Ultrasonography in (a) the longitudinal plane from the dorsal aspect shows signs of synovitis (grade 4). Axial T1-weighted magnetic resonance images were obtained (b) before and (c) after contrast administration (grade 3 synovitis). MRI, magnetic resonance imaging; RA, rheumatoid arthritis.