Rheumatoid arthritis: what do MRI and ultrasound show

Abstract

Rheumatoid arthritis is the most common inflammatory arthritis, affecting approximately 1% of the world's population. Its pathogenesis has not been completely understood. However, there is evidence that the disease may involve synovial joints, subchondral bone marrow as well as intra- and extraarticular fat tissue, and may lead to progressive joint destruction and disability. Over the last two decades, significant improvement in its prognosis has been achieved owing to new strategies for disease management, the emergence of new biologic therapies and better utilization of conventional disease-modifying antirheumatic drugs. Prompt diagnosis and appropriate therapy have been recognized as essential for improving clinical outcomes in patients with early rheumatoid arthritis. Despite the potential of ultrasonography and magnetic resonance imaging to visualize all tissues typically involved in the pathogenesis of rheumatoid arthritis, the diagnosis of early disease remains difficult due to limited specificity of findings. This paper summarizes the pathogenesis phenomena of rheumatoid arthritis and describes rheumatoid arthritis-related features of the disease within the synovium, subchondral bone marrow and articular fat tissue on MRI and ultrasound. Moreover, the paper aims to illustrate the significance of MRI and ultrasound findings in rheumatoid arthritis in the diagnosis of subclinical and early inflammation, and the importance of MRI and US in the follow-up and establishing remission. Finally, we also discuss MRI of the spine in rheumatoid arthritis, which may help assess the presence of active inflammation and complications.

Keywords: early arthritis; imaging; magnetic resonance imaging; rheumatoid arthritis; ultrasonography.

Fig. 1

MRI, T1 TSE (time spin echo) FS (fat saturation) CM (contrast medium), A. axial plane; B. coronal plane: synovitis, erosions and inflammatory cysts in the radio-carpal, midcarpal, carpo-metacarpal and metacarpophalangeal joints

Fig. 2

Ultrasound: synovitis in the PIP (proximal interphalangeal) 2 joint

Fig. 3

MRI, T1 TSE FS CM, axial plane: midcarpal joint synovitis, tenosynovitis of the flexors and 4^th compartment of extensor tendons

Fig. 4

Ultrasound, longitudinal view of tenosynovitis of the extensor carpi ulnaris tendon

Fig. 5

Subacromial bursitis in MRI, T1 TSE FS CM

Fig. 6

Ultrasound: gastrocnemius-semimembranous bursitis

Fig. 7

MRI, bone marrow edema in the distal radius

Fig. 8

Hand and wrist DCE-MRI: A. ROI covers the MCP 2 joint; B. white curve shows signal from the bone, and an orange one shows signal intensity (perfusion) from vessels of the inflamed synovium

Fig. 9

Quantifying inflammation in the radiocarpal joint with the use of the vascularity index

Fig. 10

Ultrasound, increased echogenicity and vascularization of the Kager’s fat pad

Fig. 11

MRI: A. coronal T1 TSE FS CM; B. axial T1 FS: metatarsophalangeal (MTP) 1 and MTP 5 synovitis and erosions

Fig. 12

Ultrasound, longitudinal view of the radiocarpal and middcarpal joints: synovitis and erosions

Fig. 13

Cervical spine: A. CT and MRI; B. sagittal T1-weighted image; C. sagittal T2-weighted image; D. axial T2-weighted image: dens erosions, vertical subluxation (basilar invagination), multilevel instability with a tendency to C4-C6 kyphosis and spinal cord compression