Vascular ultrasound (US) is now recommended by EULAR as the first line investigation in acute Giant Cell Arteritis (GCA), provided there is appropriate equipment and expertise available. Advances in equipment and techniques can detect characteristic sonographic findings. If these are present in the context of a suggestive clinical history and examination, it allows for a diagnosis of GCA without the need to progress to temporal artery biopsy (TAB). This has multiple advantages. Clinically US has increased sensitivity compared to TAB, as a larger area can be examined, minimising the effect of skip lesions. It can also provide information on blood flow characteristics. As well as being clinically reliable, it is well tolerated by patients with no side effects or radiation involved. It is becoming more widely available in the clinic setting, but more needs to be done to improve access across the country.
Timing of Ultrasound in GCA is very important. The sensitivity and specificity reduces quickly after the introduction of glucocorticoids, so scans should ideally be performed within a few days of starting treatment. Glucocorticoids cannot safely be delayed in suspected GCA whilst awaiting investigation, which should be taken into account when interpreting results. As well as diagnosis, vascular US may also be utilised in the follow-up of patients with GCA. With the introduction of new treatments such as tocilizumab, objective measures of determining disease activity, such as C-reactive protein, cannot be used. In this instance, persistent or re-occurring positive US findings can help monitor treatment response. With advances in cross-sectional imagining, the proportion of GCA patients with extra-cranial involvement is thought to be higher than previously recognised. In evidence to suggest that additional US of axillary arteries would be a useful screening tool, and increase the diagnostic yield of US for LV-GCA. For US to be reliably established as the primary investigation of choice, a standardised framework must be employed. This is outlined in this talk. We suggest interested clinicians develop experience in specialist GCA clinics, obtain access to appropriate machines, transducers and settings and practice with mentorship from specialist GCA clinicians/sonographers.
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