Halo Sign Vanishing Time After Steroids Outbreak in GCA Patients

Giant cell arteritis (GCA) is a rare disease characterized by vasculitis of the large arterial trunks targeting the thoracic aorta and its dividing branches, affecting adults over the age of 50. Vasculitis lesions cause thickening of the arterial wall, visible on temporal artery biopsy (TAB) or vascular imaging (echo-Doppler, angio-CT, angio-MRI, 18FDG PET-CT). This is a severe disease that can lead to blindness. Early diagnosis is essential, so that steroids therapy can be started as soon as possible to prevent complications. Doppler ultrasonography of the temporal arteries provides rapid, non-invasive diagnostic support. However, the recommendations do not specify how soon temporal artery Doppler should be performed after steroids treatment, except that the halo sign would disappear after about 5 days on steroids. Sensitivity seems to be better when the examination is performed early, but the time taken for the halo sign to disappear is unknown. The investigator suggests that the disappearance of the temporal artery halo sign in GCA patients is observed earlier than D14 of steroids treatment usually reported in the literature. He speculates that the sensitivity of the temporal artery Doppler decreases as early as D3 of steroids treatment, and that beyond D7 it is not useful to perform this examination as its sensitivity becomes too low.