Background: Rapid and reliable diagnostic procedure is crucial to prevent permanent ischemic complications in patients with suspected giant cell arteritis (GCA). Imaging methods, especially colour-Doppler sonography (CDS), are thus becoming increasingly important in the diagnosis of GCA. CDS examination is currently based on the qualitative interpretation of an experienced examiner (presence of a halo sign), which may limit its wider applicability. The data on the frequency and clinical consequences of involvement of cranial arteries other than temporal arteries are scarce.
Objectives: The main objective of the study was to determine the cut-off thickness of the arterial wall of the examined arteries that distinguishes with high diagnostic accuracy between patients with GCA and persons in whom this disease is unlikely. An additional aim of the study was to determine whether involvement of the facial and occipital arteries is associated with specific clinical characteristics in patients diagnosed with GCA.
Materials and methods: This prospective observational study included consecutive individuals referred to the Clinical Department of Rheumatology at the University Medical Centre Ljubljana due to suspected GCA. We systematically collected their demographic, clinical, and laboratory data, performed CDS of the temporal and axillary arteries (which are included in the latest recommendations for imaging diagnostics in GCA) and five additional paired arteries (facial, occipital, common carotid, vertebral, and subclavian). During the CDS examination, we recorded the presence of a halo sign and the maximum intima-media thickness at sites without evident focal thickening or atherosclerotic plaques. To determine the cut-off thickness of the vascular wall, we compared the thickness of the intima-media complex of affected arteries in patients with GCA with the thickness of the intima-media complex in subjects from the control group.
Results: During the 72-month observation period from October 1, 2013, to September 30, 2019, we included 349 patients and identified 248 new cases of GCA; 101 individuals were included in the control group. The halo sign in any of the examined arteries was recorded in 244 (98.4%) patients with a clinical diagnosis of GCA. In 23 (9.3%) patients with GCA, we found the “halo” sign exclusively in (at least) one of the arteries not currently included in the diagnostic imaging recommendations for GCA. The following intima-media thickness cut-off values distinguished with high diagnostic accuracy between inflamed and non-inflamed vessel walls of the examined arteries: temporal, facial, and occipital arteries: ≥ 0.4 mm; common carotid, subclavian, and axillary arteries: ≥ 1.0 mm; vertebral arteries: ≥ 0.7 mm. We confirmed a statistically significant association between vasculitic facial artery involvement, jaw claudication and permanent visual disturbances.
Conclusions: Examination of several different arteries can improve the diagnostic effectiveness of CDS in patients with suspected GCA. The proposed cut-off values for intima-media thickness are highly sensitive and specific. We demonstrated a statistically significant correlation between facial artery involvement and salient clinical characteristics of GCA.
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