Juan Molina-Collada ^1,2* Philipp Bosch ³ Eugenio De Miguel ⁴ Wolfgang A Schmidt ⁵ Christian Dejaco ^6,7

• ¹ Gregorio Marañón Hospital, Madrid, Spain
• ² Instituto de Investigación Sanitaria Gregorio Marañón, Madrid, Madrid, Spain
• ³ Medical University of Graz, Graz, Styria, Austria
• ⁴ Servicio de Reumatología, Hospital Universitario La Paz, Madrid, Asturias, Spain
• ⁵ Immanuel Hospital Berlin, Berlin, Baden-Württemberg, Germany
• ⁶ Department of Rheumatology, Bruneck Hospital, Bruneck, Italy
• ⁷ University of Graz, Graz, Styria, Austria

Due to the heterogeneity of clinical manifestations, diagnosing, monitoring, and stratifying risk in large vessel vasculitis (LVV) can be challenging. As a result of technological progress, imaging plays an increasing role in the management of LVV. Ultrasound (US), 18-FDG positron emission tomography/computed tomography (PET/CT), magnetic resonance imaging (MRI), and CT have proven diagnostic value and yielded promising data for the assessment of disease activity in giant cell arteritis (GCA) and Takayasu arteritis (TAK) (1). Since the first description of the use of US in GCA in 1995 (2), numerous studies have confirmed the diagnostic value of imaging for LVV, and the latest 2023 EULAR recommendations(3) reinforce the use of imaging for diagnosis, as well as its potential role in monitoring and assessment of vascular damage.Moreover, imaging was included for the first time in the new 2022 ACR/EULAR classification criteria for GCA(4) and TAK (5). Temporal artery (TA) US carries the same weight as TA biopsy for GCA classification, and evidence of vasculitis by imaging is an absolute requirement for the application of the TAK classification criteria. However, several unmet needs remain, such us investigating the value of imaging composite scores for diagnosing, monitoring and prognosis of LVV, the prognostic value of positive imaging in patients in clinical remission, and the optimal timing for using imaging to detect vessel wall damage. In addition, as technological advances require constant validation of new imaging applications, this field is continuing to evolve. The articles included in the current Research Topic provide new insights and potential applications of imaging in LVV management.Recently, interest has grown in using US to quantify vascular inflammation in GCA, and several US scores have been proposed for diagnosis and monitoring(6-10). However, they require extensive validation before they can be applied in research and clinical practice(3). In the current Research Topic, Conticini et al. investigated the diagnostic accuracy of three scores (Southend halo score, halo count and OMERACT GCA US Score (OGUS)) in 79 patients with suspected GCA. All three scores showed good sensitivity (>70%) and excellent specificity (97%). In particular, for OGUS, a threshold of 0.81 could be employed for diagnostic purposes, although this score was primarily developed for monitoring. Schweiger et al. retrospectively investigated the incidence and predictors (including US determined intima-media thickness (IMT)) of glucocorticoid related side effects in 138 patients with GCA. Chronic kidney disease, fractures, cataracts, dementia, and hypertension were the most frequent events. In multivariable analysis, relapses during follow-up predicted diabetes, likely due to increased glucocorticoid use. However, analytical parameters of inflammation and endothelial dysfunction, including pulse-wave velocity and IMT by US were not linked with adverse events of glucocorticoids.The diagnosis of GCA by US relies on traditional elementary lesions such us the halo sign (inflammatory concentric thickening of the arterial wall). The halo sign is normally determined on a visual basis applying the OMERACT criteria (11). However, there are ongoing efforts to establish cut-offs for the measurement of the arterial wall thickness (IMT) in different territories for diagnostic and monitoring purposes (12)(13)(14)(15). Seitz et al.