DECT Scans Unable to Detect Gout Nephropathy

Tristan Pascart, MD, PhD

Credit: Research Gate

New research has found that dual-energy computed tomography (DECT) is unable to detect genuine MSU crystal deposits in kidneys and renal artery walls but can characterize chronic asymptomatic urolithiasis.¹

“DECT has been extensively demonstrated to identify MSU crystal deposition around joints but its ability to detect MSU crystals in the kidneys and vessel walls is unclear. Optimizing DECT post-processing default settings improves the specificity of MSU deposit detection. The ability of DECT to effectively characterize the chemistry of kidney stones, and in particular to distinguish uric from non-uric stones, has been well demonstrated.² The objective of this study was to explore whether DECT can detect MSU crystal deposits in the renal medulla or cortex and renal artery walls, and uric acid urolithiasis, in patients with gout and chronic kidney disease (CKD),” lead investigator Tristan Pascart, MD, PhD, professorDepartment of Rheumatology, Lille Catholic University, Saint-Philibert Hospital, ETHICS laboratory, Lille, EA, France, and colleagues wrote.¹

Pascart and colleagues conducted a cross-sectional study including patients with gout and stage 2-4 CKD to undergo renal, knee and feet DECT scans. They used different post-processing settings to read renal DECT scans for MSU-coded lesions in the kidneys, renal artery walls, and urinary tract. They compared characteristics of patients with and without DECT-positive lesions and measured the DECT parameters of these lesions.

The investigators included 27 participants with gout and DECT scans in their analysis, with a mean age of 73 years old (standard deviation [SD], 9), a mean eGFR of 45.3 mL/min/1.73 m² (SD, 21.0), and MSU volumes in the knees and feet ranging from 0.11 to 475.0 cm³.¹

Pascart and colleagues did not observe any MSU crystal deposition in the kidneys on DECT scans. They did observe 1 case of calyceal calculi and 1 case of ureterolithiasis that were wrongly coded as MSU in default post-processing settings for gout but identified as uric acid in the “kidney stone” settings. They found that 5 patients had MSU-coded plaques in the renal arteries, which had DECT parameters consistent with early calcified plaques instead of MSU, and which had no association with peripheral MSU deposition volumes.

“This study shows that despite promising abilities, DECT was not able to detect evidence of gout nephropathy, even in patients with extensive MSU crystal deposition around the joints which were expected to be at risk of also presenting deposits in the renal tissue. Caution is warranted when DECT identifies MSU-coded plaques in renal arteries, unrelated to the general MSU crystal burden, which are most probably miscoded due to calcified plaques. As expected, kidney DECT scans were able to detect and characterize uric acid urolithiasis in people with gout and CKD,” Pascart and colleagues wrote.¹
The investigators stressed the importance of using optimized settings in “gout mode” on DECT scans, pointing out that default settings tended to inaccurately classify uric acid kidney stones as MSU.

REFERENCES

1. Pascart T, Dauphin E, Yokose C, et al. The role of renal dual-energy computed tomography in exploring the gouty kidney: the RENODECT study. Ann Med. 2025;57(1):2458783. doi:10.1080/07853890.2025.2458783

2. Pascart T, Budzik JF. Dual-energy computed tomography in crystalline arthritis: knowns and unknowns. Curr Opin Rheumatol. 2022;34(2):103–110. doi: 10.1097/BOR.0000000000000863.