The value of ultrasound for monitoring disease activity in giant cell arteritis

Giant cell arteritis (GCA) is the most common primary systemic vasculitis in the elderly. Although the diagnosis of GCA has improved, monitoring its disease activity remains challenging due to the lack of validated tools and biomarkers. The current reliance on assessing symptoms, physical signs, and inflammatory markers during disease follow-up presents limitations, notably the nonspecific nature of GCA-related symptoms and the suppressive impact of IL-6 inhibitors on inflammatory markers. Therefore, recent attention has shifted toward acknowledging imaging as a monitoring tool, particularly ultrasound, given its widespread accessibility, cost-effectiveness, and well-established role in GCA diagnosis. Research on this topic has found that ultrasound characteristics, including the number of affected arterial segments and halo size, are associated with laboratory markers and treatment response, underscoring the ultrasound’s potential as a monitoring tool for GCA. It has also been demonstrated that ultrasound abnormalities progress differently throughout the disease course, depending on the type of arterial involvement, with vessel wall changes in the axillary arteries resolving more slowly than those in the temporal arteries. Nevertheless, there are still no studies comparing the added value of regular ultrasounds for monitoring disease activity to clinical and laboratory monitoring alone; hence, this imaging modality is not yet recommended for patients with GCA in clinical and biochemical remission. This narrative review aims to synthesize the main research findings of key studies addressing the role of ultrasound for monitoring disease activity in GCA, with a focus on the pattern of arterial involvement. It highlights the potential of ultrasound, particularly halo sign assessment, for evaluating disease progression but notes that further validation and standardization of protocols are needed to improve accuracy and enable routine use.