From the Guidelines
Dual-energy CT (DECT) is a highly valuable tool for diagnosing gout, particularly in cases where conventional diagnostic methods are inconclusive, as it offers excellent sensitivity and specificity for detecting monosodium urate deposits in joints and soft tissues. According to the most recent and highest quality study, the 2018 updated European League Against Rheumatism evidence-based recommendations for the diagnosis of gout 1, DECT is recommended for use in patients with atypical clinical features and in whom crystal identification is not feasible. DECT works by utilizing two different energy levels to distinguish urate crystals from calcium and other tissues, allowing for accurate identification of monosodium urate deposits in joints and soft tissues. The procedure is non-invasive and takes only minutes to perform, with the patient simply lying on the CT table while the scanner obtains images of the affected areas.
Some of the key benefits of using DECT for gout diagnosis include:
- Excellent sensitivity (80-90%) and specificity (83-93%) for detecting gout, even in early disease stages or during intercritical periods when patients are asymptomatic
- Ability to detect urate deposits before they become clinically apparent and help differentiate gout from other arthritides like pseudogout or rheumatoid arthritis
- Non-invasive and quick procedure with minimal radiation exposure
- Valuable for evaluating disease burden, monitoring treatment response, and guiding management decisions in patients with suspected or established gout
While joint aspiration with polarized microscopy remains the gold standard for gout diagnosis, DECT offers significant advantages when aspiration is difficult, inconclusive, or refused by the patient. The main limitations of DECT include cost and potential false positives from artifacts. However, the benefits of DECT make it a highly recommended tool for diagnosing gout, particularly in cases where conventional diagnostic methods are inconclusive.
From the Research
Role of Dual Energy Computed Tomography (DECT) in Diagnosing Gout
- DECT allows for non-invasive detection of monosodium urate (MSU) crystal deposits and has become incorporated into the routine clinical evaluation for gout 2, 3, 4.
- The technique has a high sensitivity (90-100%) and a high specificity (83-89%) for diagnosing gout 2.
- DECT enables the direct visualization of sodium urate deposition, disease activity, and monitoring of tophaceous gout 2.
- A positive DECT scan is one of the 2015 ACR/EULAR classification criteria for gout 2, 4.
- DECT can quantify urate burden and potentially avoid invasive diagnostic procedures 5.
Advantages of DECT in Gout Diagnosis
- Non-invasive alternative to synovial fluid aspiration 6.
- Useful in diagnosing cases of gout where synovial fluid fails to demonstrate monosodium urate crystals 6.
- Can detect extra-articular MSU deposition in soft tissue and identify axial MSU deposition in gout patients with non-specific back pain 5.
- Correlates with high coronary calcium scores and elevated Framingham cardiovascular risk 5.
Clinical Applications of DECT
- Guiding the management of patients with suspected gout and monitoring the effectiveness of urate-lowering medical therapy 4.
- Aiding in the understanding of articular and extra-articular MSU deposition, including the role of vascular MSU deposition on cardiovascular health 5.
- Evolving role for DECT in the evaluation of gout after an institution's routine adoption of the technology for this purpose 3.