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Objectives The Gout, Hyperuricaemia and Crystal-Associated Disease Network (G-CAN) has developed a calcium pyrophosphate deposition (CPPD) nomenclature project. This systematic literature review constituted its first step and aimed to provide a state-of-the-art analysis of the medical literature of the last 20 years.Methods A systematic literature search was undertaken in the PubMed, Cochrane and Embase databases between 2000 and 2022, restricted to studies on humans and in the English language. Eight reviewers independently and manually extracted labels related to CPPD concepts, according to an a priori list generated by the authors: pathogenic conditions and pathogenic crystal labels, elementary imaging condition elements and asymptomatic and symptomatic condition states. For each concept, labels were analysed to determine their frequency.Results Among the 2375 articles identified, 886 articles were included, of which 394 (44.5%) were case reports and 169 (19.0%) were scoping reviews. Overall, the most common labels used to designate the pathogenic condition were ‘pseudogout’ in 365/783 (46.6%), ‘chondrocalcinosis’ in 207/783 (26.4%) and ‘calcium pyrophosphate deposition disease’ in 181/783 (23.1%) occurrences. The most common abbreviation was ‘CPPD’ in 312/390 (80.0%), but with different meanings. CPPD clinical phenotypes were often described as ‘pseudo-form’ labels.Conclusion Those results demonstrate the heterogeneity of labels used to describe CPPD condition concepts, with wide variation in condition labels in the medical literature. This work provides the rationale and basis to achieve agreement about CPPD technical nomenclature.

Objective To examine factors influencing the kinetics of monosodium urate (MSU) crystal dissolution measured with dual-energy computed tomography (DECT) during follow-up of patients with gout.Methods Patients with a diagnosis of gout with baseline knees and feet DECT scans exhibiting MSU crystal volumes ≥0.1 cm3 and at least one follow-up DECT were included. Spearman’s correlation coefficient was used to search for association between change from baseline MSU crystal volume at 6, 12, 18 and 24 months and serum urate (SU) level. Associations between percentage change from the baseline volume of MSU crystal deposits and explanatory variables were assessed using linear mixed models.Results Sixty-two patients (age 67.3±12.8 years; 53 (85%) males) cumulating 104 follow-up DECT scans were included. Overall, SU target levels (

Objective The objective of this study was to explore the ability of dual-energy computed tomography (DECT) to detect monosodium urate (MSU) crystal deposits in the kidneys and renal artery walls, and uric acid urolithiasis, in patients with gout and chronic kidney disease (CKD).Methods Patients with gout and with stage 2–4 CKD were prospectively included in this cross-sectional study. Patients underwent renal, knee and feet DECT scans. Renal DECT scans were read for MSU-coded lesions in the kidneys, renal artery walls, and urinary tract using different post-processing settings. Characteristics of patients with and without DECT-positive lesions were compared, and the DECT parameters of these lesions were measured.Results A total of 27/31 patients with had renal DECT scans and were included in the analysis (23/27 men, mean (standard deviation) 73 (9) years old, mean eGFR 45.3 mL/min/1.73 m2 (21.0), volumes of MSU in the knees and feet ranging from 0.11 to 475.0 cm3). None of the patients exhibited deposition of MSU crystals in the kidneys. One case of calyceal calculi and one case of ureterolithiasis were observed, wrongly coded as MSU in default post-processing settings for gout but identified as uric acid in the “kidney stone” settings. Five patients had MSU-coded plaques in the renal arteries, which had DECT parameters consistent with early calcified plaques rather than MSU, and had no association with volumes of peripheral MSU deposition.Conclusion DECT is unable to detect genuine monosodium urate crystal deposits in kidneys and renal artery walls, and but can characterize chronic asymptomatic urolithiasis.