Descriptive Analysis of Dual-energy Computed Tomography Exams of Adult Patients With Gout

Study Overview
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Brief Summary
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The main objective is to describe urate deposits (especially in terms of distribution and volume) in soft tissues and bone, and joint erosions and destruction, in adult patients with gout.

Detailed Description
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Gout is the result of hyperuricemia, itself a consequence of a disorder of purine metabolism. This hypuricemia can lead to the deposition of sodium urate crystals in the soft tissues. It is the deposition of sodium urate crystals in and near the joints that causes an intense local inflammatory reaction with episodes of acute joint pain, swelling and functional disability. In the long term, uratic concretions in the soft tissues (tophus) occur, the joints are destroyed (uratic arthropathies), the kidneys also (gouty nephropathy). Dual-energy CT (Computed Tomography) is a relatively recent technique that allows the identification of certain materials through the analysis of the difference in attenuation of the material exposed to two different X-ray spectra. This technique identifies the crystalline component of tophus.

Official Title
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Descriptive Analysis of Soft-tissue Urate Deposits, and Bone and Joint Destruction in Dual-energy Computed Tomography Exams of Adult Patients With Gout

Conditions
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Gout

Intervention / Treatment
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* Diagnostic Test: Dual-energy computed tomography


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Age greater than or equal to 18 years old; Patient with a gout according to ACR (American College of Rheumatology) criteria; Affiliated with a social security scheme. Dual-energy scanner examinations stored in the PACS at Lariboisière Hospital Exclusion Criteria: Pregnant or breastfeeding woman.

Ages Eligible for Study
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Minimum Age: 18 Years

Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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No

Study Plan
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How is the study designed?
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Arms and Interventions

| Intervention/Treatment |
| --- |
|Diagnostic Test: Dual-energy computed tomography|Dual-energy scanner examinations stored in the PACS (medical imagery) at Lariboisière Hospital are to be analyzed retrospectively and prospectively|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Soft tissue tophus description | Description of soft tissue tophus in terms of location, size, density at high and low energy | The day of the CT (computed tomography) examination | 
| Distribution of urate deposits | Distribution of urate deposits in soft tissues and bone, and joint erosions and destruction | The day of the CT examination | 
| Descriptive analysis of joint erosions and destruction | Descrition of joint erosions and destruction :erosion size (mm) and location (joint), joint destruction (space narrowing, joint collapse, joint ankylosis). | The day of the CT examination | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Correlation of the descriptive parameters on dual-energy CT with clinical data | to correlate the descriptive parameters on dual-energy CT with clinical data, including disease history and therapeutic management, and serum urate level. | The day of the CT examination | 
| Variations in tophaceous burden | To study the variations in tophaceous burden according to the choice of technical parameters for deposit analysis.The parameters of dual energy analysis (threshold, optional filter to remove noise, gradients of dual-energy) change the quantitative value provided by the manufacturer. This outcome will be the urate volume obtained at different parameters | The day of the CT examination | 
| Link between tophus and erosions | To analyze the relationships between bone erosion scores and urate volume (correlation between quantitative values) | The day of the CT examination | 
| Reproducibility of a scoring system | To develop and evaluate the reproducibility of a scoring system for tophaceous load and structural damage using a dual energy CT. We will try to developp a scoring system combining the tophus load (total tophus volume) and the erosion score (total erosion score). | The day of the CT examination | 
| Bone mineral density | To evaluate the bone mineral density at the distal radius and correlate it with tophaceous load and joint structural damage. A region of interest at the distal radius (one centimeter above the joint space) will be placed using the computer mouse to obtained the bone mineral density (in Hounshield unit, mean bone mineral density within the ROI (Region Of Interest)). | The day of the CT examination | 
| Tophus texture | To evaluate tophus texture. The texture of the tophus will be approached qualitatively (homogeneous/heterogeneous) and according to its density (Hounsfield unit) and to the percentage of tophus color-coded by the dual energy analyse. | The day of the CT examination |