An analysis of the first relapse in giant cell arteritis using ultrasonography

Objectives: To compare the nature of the first relapse of giant cell arteritis to baseline disease using ultrasonography Methods: Patients with suspected new and relapsing giant cell arteritis between January 2017 and December 2023 underwent protocolised ultrasonography to examine the superficial temporal and axillary arteries plus other areas as clinically indicated. The nature of disease was categorised as affecting superficial temporal, axillary or mixed disease. Patients where other arteries were needed for diagnosis or relapse were categorised separately. Patients with clinically and sonological evidence of polymyalgia rheumatica were distinctly categorised. Results: 66 patients were included. At diagnosis and first relapse, 48/66 and 20/66 patients respectively had superficial temporal artery involvement. At diagnosis and first relapse, 23/66 and 40/66 respectively patients had axillary artery involvement. Patients without superficial temporal artery disease at diagnosis did not relapse in the superficial temporal artery. 7/66 patients suffered a polymyalgia rheumatica relapse. 5 of those 7 had superficial temporal arterial involvement at diagnosis. Conclusion: This is the first study that reports on the nature of relapsing giant cell arteritis using sonological appearances. Relapsing disease is more common in the extracranial arteries and may be mistaken for polymyalgia rheumatica. True polymyalgia rheumatica relapses are uncommon. Relapses in patients with giant cell arteritis should be assessed using ultrasonography and should include the imaging of the axillary artery.