Diagnostic yield of facial artery ultrasound in addition to temporal and axillary artery ultrasound for the diagnosis of giant cell arteritis

OBJECTIVES: Ultrasound of the temporal and axillary arteries is recommended as the first-line imaging test for suspected giant cell arteritis (GCA), but the additional diagnostic yield of facial artery ultrasound (facUS) remains unclear. METHODS: In this retrospective study, patients with suspected GCA who underwent standardised ultrasound of the temporal arteries (tempUS) and axillary arteries (axUS) were included if both facial arteries had also been examined. Clinical, laboratory, sonographic and histopathological data were retrieved from the electronic medical records. The diagnostic accuracy of facUS was determined by ROC-curve analysis and 2x2 contingency tables. Patients with and without facial artery involvement were compared by univariate significance tests. RESULTS: Among 69 included patients, 37 were diagnosed with GCA and 32 with other conditions. FacUS-values >0.7 mm were found in 34 patients (26 GCA, 8 non-GCA) and >1.0 mm in 18 patients (17 GCA, 1 non-GCA). When facUS was added to tempUS and axUS, sensitivity increased to 97.3% (+8.1%) but specificity decreased to 65.6% (-18.8%) when a cutoff >0.7 mm was applied. With a cutoff >1.0 mm, diagnostic accuracy changed only marginally. Eleven patients showed negative tempUS but positive facUS results; five of them were ultimately diagnosed with GCA (three of whom had isolated facial artery involvement). CONCLUSIONS: FacUS provides limited additional diagnostic yield when added to temporal and axillary artery imaging in suspected GCA but may be performed in selected patients with strong clinical suspicion and negative temporal ultrasound findings.