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.
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.
Study Type
OBSERVATIONAL
Enrollment
150
Dual-energy scanner examinations stored in the PACS (medical imagery) at Lariboisière Hospital are to be analyzed retrospectively and prospectively
Hôpital Lariboisière - Service d'Imagerie OstéoArticulaire, Viscérale et Vasculaire
Paris, France
RECRUITINGHôpital Lariboisière - Service de Rhumatologie
Paris, France
RECRUITINGHôpital Bichat - Service de Rhumatologie
Paris, France
RECRUITINGSoft tissue tophus description
Description of soft tissue tophus in terms of location, size, density at high and low energy
Time frame: 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
Time frame: 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).
Time frame: The day of the CT examination
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.
Time frame: 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
Time frame: 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)
Time frame: The day of the CT examination
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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).
Time frame: 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)).
Time frame: 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.
Time frame: The day of the CT examination