Dual‐energy CT in gout – A review of current concepts and applications

Abstract

Dual‐energy computed tomography (DECT) is a relatively recent development in the imaging of gouty arthritis. Its availability and usage have become increasingly widespread in recent years. DECT is a non‐invasive method for the visualisation, characterisation and quantification of monosodium urate crystal deposits which aids the clinician in the early diagnosis, treatment and follow‐up of this condition. This article aims to give an up to date review and summary of existing literature on the role and accuracy of DECT in the imaging of gout. Techniques in image acquisition, processing and interpretation will be discussed along with pitfalls, artefacts and clinical applications.

Joint Clinical Consensus Statement of the American College of Foot and Ankle Surgeons® and the American Association of Nurse Practitioners®: Etiology, Diagnosis, and Treatment Consensus for Gouty Arthritis of the Foot and Ankle

“…The diagnosis of gout has traditionally been based on patient history, clinical findings, laboratory, and/or joint aspirate results, with imaging as an adjunct (93). For typical presentations of gout, a clinical diagnosis alone is reasonably accurate but not definitive without crystal confirmation (94,95).…”

“…Advanced images such as dual-energy computed tomography (DECT), MRI, and ultrasound have been useful in visualizing pathology resulting from gout. DECT can identify and quantify monosodium urate (MSU) crystals (93,102), whereas MRI is used to assess inflammation, bone erosion, and cartilage damage in gout (102). Low-quality evidence from 3 observational studies showed that DECT had a sensitivity of 85% to 100% with specificity of 83% to 92% for predicting gout (103).…”

“…Identification of negative birefringent MSU crystals under polarized microscopy is still considered the gold standard for diagnosing gout (8,93,100). Confirmation of MSU crystals in synovial fluid via joint aspiration is highly recommended in cases where classic features are not present to assist in definitive diagnosis (94,112).…”

“…Alternatively, in a study by Swan, a 25% false negative rate was seen in cases of acute gout (113). This may have been secondary to the major limitation associated with joint aspiration, which is the need for proper skills and sufficient joint fluid for testing (93,94) Another barrier to joint aspiration in cases of acute gout is "where the affected joint is inaccessible" (93).…”

Spinal tophaceous gout presenting in a young adult without pain

“…MRI and CT investigations are considered non-specific, but may show homogenous changes on T1 and T2 imaging 11. Likewise, dual energy CT, which is used for identifying appendicular gout, is not ideal for imaging of spinal gout due to poor sensitivity for MSU crystals 12. The gold standard diagnosis is through biopsy of the spine and pathological analysis showing MSU crystals that are negatively birefringent under polarised light 1.…”