Ultrasound for diagnosis and follow-up of chronic axillary vasculitis in patients with long-standing giant cell arteritis

AIMS: To assess intima-media thickness (IMT) changes measured by ultrasound in axillary arteries of giant cell arteritis (GCA) patients over time and to calculate an ultrasound cut-off value for the diagnosis of chronic axillary artery involvement in patients with longstanding GCA. METHODS: Ultrasound of both axillary arteries was performed in 109 GCA patients at time of diagnosis and at several follow-up visits and in 40 healthy controls (HCs). IMT determined at the prospective follow-up visit was compared between GCA patients with (axGCA) and without (non-axGCA) vasculitis of axillary arteries at baseline, as well as with HCs. Changes in IMT were depicted. Receiver operating characteristics were performed for cut-off calculations. Inter-/intra-rater agreement was evaluated using stored images and intraclass correlation coefficient (ICC). RESULTS: Seventy-three patients were in the axGCA and 36 in the non-axGCA group. Pathological IMT of axillary arteries (axGCA) declined in the first 18 months of treatment by −0.5 mm, (range −2.77 to 0.50), independent of age and gender. Median IMT, after median disease duration of 48 months (16–137), was 0.90 mm (0.46–2.20) in axGCA and 0.60 mm (0.42–1.0) in the non-axGCA group pooled with HCs. An IMT of 0.87 mm was highly specific (specificity 96%, sensitivity 61%) for diagnosis of chronic axGCA. Intra-rater and inter-reader agreement of ultrasound images were good [ICC 0.96–1.0 (three readers) and 0.87, respectively]. CONCLUSION: Pathological IMT of the axillary artery declined under treatment. An IMT of 0.87 mm is highly specific for diagnosis of chronic vasculitis of axillary arteries in long-standing GCA patients.