Difficult diagnosis of gout: the benefit of dual energy computed tomography, initial experience in routine clinical practice

Abstract

Gout, one of the most common inflammatory arthritides in humans, is still difficult to diagnose in challenging situations, when fluid for arthrocentesis or an apparent tophus are absent and, for example, an infection as differential diagnosis has to be ruled out. Dual energy computed tomography (DECT) is an established tool for detection and characterisation of uric acid stones in the urinary tract and has recently been used to detect and display urate deposits. Our first experiences with DECT as a diagnostic tool in routine clinical practice show, that DECT is a promising imaging technique which allows the detection of monosodium urate deposits and benefits the routine diagnosis of tophaceous gout particularly in diffuse soft tissue swelling of the limbs, without the possibility of needle aspiration. However, DECT does not seem suitable to detect dissolved urate crystals, neither in vitro nor in vivo.

Relationship between structural joint damage and urate deposition in gout: a plain radiography and dual-energy CT study

“…The linear relationship between erosion size and DECT MSU crystal deposition suggests that the resolution of DECT may not be sufficient to identify very small, microscopic areas of MSU crystal deposition associated with small erosions. Recent comparisons of DECT scanning and microscopic analysis have shown that colour-coded DECT scanning identifies areas of densely packed MSU crystals, but has lower sensitivity for sites where MSU crystals are less dense 21 22. The incomplete relationship between structural joint damage and DECT MSU crystal deposition may also be partly related to the DECT settings selected for this study.…”

Dual-energy computed tomography has limited sensitivity for non-tophaceous gout: a comparison study with tophaceous gout

“…Lockmann et al showed that DECT did not detect MSU crystals in a sample of white synovial fluid containing a high concentration of these crystals by polarized light microscopy (i.e. “gout milk”) [ 25 ]. In the pathologic examination conducted by Melzer et al, tophi with a density throughout most of their volume below 150 Hounsfield units were not color-coded by the DECT imaging software, thereby limiting the sensitivity of DECT for low-density tophi [ 24 ].…”