What is the role of MRI of the hand in the evaluation of rheumatoid arthritis (RA)?

Updated: Mar 28, 2019
  • Author: Ian Y Y Tsou, MBBS, FRCR; Chief Editor: Felix S Chew, MD, MBA, MEd  more...
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Answer

MRI provides images with good delineation of soft-tissue changes, cartilaginous defects, and osseous erosions associated with RA. In particular, the ability to detect synovial hypertrophy and pannus formation before the onset of bony erosions has become more valuable with the advent of disease-modifying antirheumatic drugs. The drugs, which retard the progression of RA, are most effective in the early stages of disease. [3, 4, 8, 9, 10]  MRI has been shown to be more sensitive to early changes in RA, and in the appropriate clinical setting, it is more accurate than plain radiography in the diagnosis of RA.

Signal intensity of the inflamed synovial lining may vary markedly on T1- and T2-weighted images. An inflamed synovial lining usually demonstrates low signal intensity on T2-weighted images, and the images may be even darker if hemosiderin or a predominantly fibrous component is present within the lining. Tenosynovitis resulting from inflammation is seen as high–signal-intensity fluid on T2-weighted sequences; see the image below.

Coronal fine-section gradient echo MR image demons Coronal fine-section gradient echo MR image demonstrates multiple erosions in the carpal bones and bases of the metacarpals, with pannus formation around the distal ulna.

The intravenous (IV) administration of a gadolinium-based contrast agent allows better distinction of inflammatory soft-tissue changes and can help differentiate pannus from eburnation. In addition, rapid enhancement of proliferative inflammatory synovium has been reported, compared to minimal signal change in healthy soft tissue and bone. Fat suppression and fast dynamic scanning have also been used to increase the sensitivity of synovial imaging. [13, 14, 15]

Gadolinium-based contrast agents have been linked to the development of nephrogenic systemic fibrosis (NSF) or nephrogenic fibrosing dermopathy (NFD). These diseases have occurred in patients with moderate to end-stage renal disease after being given a gadolinium-based contrast agent to enhance MRI or magnetic resonance angiography (MRA) scans. NSF/NFD are debilitating and sometimes fatal diseases. Characteristics include red or dark patches on the skin; burning, itching, swelling, hardening, and tightening of the skin; yellow spots on the whites of the eyes; joint stiffness with trouble moving or straightening the arms, hands, legs, or feet; pain deep in the hip bones or ribs; and muscle weakness.

MRI is clearly superior to radiography in the early detection of bone erosions. MRI is more sensitive to bone marrow edema. Bright lesions on T2-weighted images often do not correspond to findings on radiographs or T1-weighted images. These lesions are believed to represent potentially reversible pre-erosive changes. [16, 17] See the images below.

Axial proton-density weighted MR image at the leve Axial proton-density weighted MR image at the level of the radio-carpal joint shows extensive tenosynovitis involving the dorsal extensor and volar flexor tendons, with fluid in the tendon sheaths.
Axial T2-weighted fat-suppresed MR image at the le Axial T2-weighted fat-suppresed MR image at the level of the carpal bones shows diffuse synovial hypertrophy over the dorsal aspect (arrows), with a heterogenous appearance and adjacent fluid. Fluid is also present in the dorsal extensor tendon sheaths.
Axial T1-weighted MR image of the wrist before and Axial T1-weighted MR image of the wrist before and after gadolinium administration shows diffuse contrast enhancement in the areas of synovial hypertrophy and thickening, over both the dorsal and volar aspects.

Routine use of MRI in evaluating rheumatoid arthropathy in the hands and wrist has been limited by the relatively high cost, the difficulty in positioning disabled patients, and the inability to image several joints simultaneously.

Olech et al evaluated the sensitivity and specificity of MRI in detecting erosions, bone edema, and synovitis in the metacarpophalangeal and wrist joints for RA by comparing scans of bilateral hands and wrists of 40 healthy subjects with those of 40 RA patients using 0.2 T extremity-MRI. A total of 3,360 bones were evaluated, and patients with RA were found to have significantly more erosions, as well as higher scores for bone edema and synovitis. Although age had a significant effect on the number of erosions in both groups, age became insignificant in RA patients when disease duration was factored in. The number of erosions correlated with positive rheumatoid factor and higher C-reactive protein values. Bone marrow edema was the most specific MRI lesion for RA, with 65% sensitivity and 82.5% specificity. [18]

In a study by Lisbona et al, subclinical inflammation was identified by MRI in 96.4% of patients with RA who had achieved sustained clinical remission. Significantly higher scores of bone marrow edema were observed after sustained remission in patients with progression of erosions, as compared to patients with no erosion progression. According to the authors of the study, persistence of higher scores of BME may explain the progression of bone erosions in patients with persistent clinical remission. [19]

According to one study, using MRI with maximum intensity projection (MIP) images, together with palpation, makes detailed evaluation of synovitis of the hand in RA easy. The researchers concluded that MIP images may predict further joint damage because they allow semiquantitative estimation of the degree of thickening of the synovial membrane. [20]

Contrast-enhanced MRI with maximum intensity projection (MRI-MIP) has been found to be a useful imaging technique to evaluate synovitis in hands with RA. [21]


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