Diagnostic imaging of gout: comparison of high-resolution US versus conventional X-ray

Abstract

The aim was to compare X-ray and ultrasound (US) in diagnosing gout. In a prospective study, 105 consecutive patients with clinical suspicion of gout underwent conventional X-ray und high-resolution US in order to help in arriving at a definite diagnosis. X-ray findings suggestive of gout included soft-tissue opacifications with densities between soft tissue and bone, articular and periarticular bone erosions, and osteophytes at the margins of opacifications or erosions. US findings suggestive of gout included bright stippled foci and hyperechoic soft-tissue areas. Fifty-five patients had a definite diagnosis of gout (102 involved sites), 31 patients were diagnosed as having another disease (59 involved sites), and 19 patients were excluded from the study because a definite diagnosis could not be established. X-ray suggested gout with a sensitivity of 31% (32/102) and a specificity of 93% (55/59), whereas US suggested gout with a sensitivity of 96% (98/102) and a specificity of 73% (43/59). US was much more sensitive than conventional X-ray but less specific. Our data show that US often provided additional diagnostic information in patients with clinical suspicion of gout when laboratory findings and X-ray results were negative or inconclusive and should therefore be used in these cases.

Is ultrasound changing the way we understand rheumatology? Including ultrasound examination in the classification criteria of polymyalgia rheumatica and gout.

“…Important advances in gout management have recently been made: the development not only of modern imaging techniques [32][33][34][35] that have the ability to recognize gout better and earlier, but also of potent new drugs, including biologic agents. These advances emphasize the need for robust gout classification criteria that need to have acceptably high specificity to ensure that enrolment in trials testing new therapies is targeting patients with definite gout [36].…”

Musculoskeletal ultrasonography in gout

“…Joint effusion is a frequent finding in gout and the presence of hyperechoic spots within effusion may be suggestive for the disease, being related to the presence of crystals aggregates. These aggregates have less than 1 mm and, during the examination, when pressing the probe on the surface of the examined structure, they float inside the joint realizing a characteristic "snowstorm appearance" [34,35]. Using US it is possible to identify joints with effusion and to perform US-guided aspiration with the aim of identifying crystals at synoval fluid analysis, which is considered the gold standard for the diagnosis [9].…”

“…Using US it is possible to identify joints with effusion and to perform US-guided aspiration with the aim of identifying crystals at synoval fluid analysis, which is considered the gold standard for the diagnosis [9]. Synovial hypertrophy and hypervascularisation can be also detected and, even though they are non specific findings, the possible presence of hyperechoic spots or cloudy areas in the synovium are strongly evocative for gout [34]. The presence of power Doppler signal indicates, as well as in the other forms of arthritis, active inflammation.…”

The place of musculoskeletal ultrasonography in gout diagnosis

“…Comparing US with x-ray findings, the erosions suggestive for gout are detected more often by US [25,26] proven to be a moderately specific (69%) but with a low sensitivity imaging method (24%) [27]. The main limitation of the method are the lack of clear criteria for differentiation the gout erosions from erosions of other inflammatory arthritis (RA, spondyloarthritis, etc).…”

“…The erosions are Fig 1. a) Longitudinal scan of the first metatarsophalangeal (MTF) joint-acute gout, gray scale: fluid and proliferated synovium with few hyperechoic spots; b) acute gout-hypervascularised proliferated synovium; c) intercritical gout, second MTF joint -small quantity of transonic fluid and proliferated synovium; note the double contour of the hyaline cartilage; d) longitudinal scan of the tibialis anterior tendon-intratendinous hyperechoic deposits with alteration of the fibrillar structure and tenosynovitis; e) and f) transversal scan of the tibialis anterior tendon, gray scale and color Doppler-hyperechoic deposits, tenosynovitis and hypervascularisation. usually more deeper and destructive comparing with RA [14,27] but only the association of erosions with findings suggestive for MSU deposits confer higher specificity.…”