Definitions of elementary ultrasound lesions in Takayasu arteritis: a study from the OMERACT Ultrasound Working Group.

Objective: To systematically assess the evidence on the use of ultrasonography (US) for the detection of vascular inflammation in Takayasu arteritis (TAK), with a focus on evaluating existing scoring systems and identifying elementary sonographic lesions for diagnosis, disease monitoring and outcome prediction.

Methods: A systematic literature review (SLR) was conducted using PubMed, EMBASE, the Cochrane Library and Epistemonikos from their inception until 15 March 2024. Only original research articles evaluating the diagnostic accuracy, outcome prediction or monitoring ability of US in TAK, with a minimum sample size of 15 patients, were included. Data extraction was performed independently by two reviewers. Study quality was assessed using the Quality Assessment of Diagnostic Accuracy Studies-2 tool for diagnostic studies and the Quality In Prognosis Studies tool for prognostic studies.

Results: 21 studies met the inclusion criteria. Three of them proposed a US scoring system for TAK, while the remainder focused on reporting elementary lesions. The common findings included increased intima-media thickness (IMT), stenosis, occlusion, aneurysm and increased contrast enhancement. All studies evaluated the common carotid arteries, with less frequent assessment of other vascular territories such as the subclavian and common femoral arteries and the abdominal aorta. Although increased IMT and contrast enhancement of the arterial wall correlated with clinical measures of disease activity, heterogeneity of lesion definitions and measurement thresholds, along with small sample sizes and moderate-to-high risk of bias, limits the generalisability of the findings.

Conclusions: This SLR highlights the current lack of a fully validated US scoring system for TAK and underscores the need for standardised definitions of elementary sonographic lesions.