Ultrasound halo count in the differential diagnosis of atherosclerosis and large vessel giant cell arteritis

Abstract

Objective To determine the diagnostic discriminant validity between large vessel giant cell arteritis (LV-GCA) and atherosclerosis using ultrasound (US) intima-media thickness (IMT) measurements. Methods We included 44 patients with LV-GCA and 42 with high-risk atherosclerosis. US examinations of the axillary, subclavian, and common carotid arteries (CCA) were systematically performed using a MylabX8 system (Genoa, Italy) with a 4–15-MHz probe. IMT ≥ 1 mm was accepted as pathological. Results The LV-GCA cohort included 24 females and 20 males with a mean age of 72.8 ± 7.6 years. The atherosclerosis group included 25 males and 17 females with a mean age of 70.8 ± 6.5 years. The mean IMT values of all arteries included were significantly higher in LV-GCA than in atherosclerosis. Among LV-GCA patients, IMT ≥ 1 mm was seen in 31 axillary, 30 subclavian, and 28 CCA. In the atherosclerotic cohort, 17 (38.6%) had IMT ≥ 1 mm with axillary involvement in 2 patients, subclavian in 3 patients, carotid distal in 14 patients (5 bilateral), and isolated carotid proximal affectation in 1 case. A cutoff point greater than 1 pathological vessel in the summative count of axillary and subclavian arteries or at least 3 vessels in the count of six vessels, including CCA, showed a precision upper 95% for GCA diagnosis. Conclusion The IMT is higher in LV-GCA than in atherosclerosis. The proposed US halo count achieves an accuracy of > 95% for the differential diagnosis between LV-GCA and atherosclerosis. The axillary and subclavian arteries have higher discriminatory power, while carotid involvement is less specific in the differential diagnosis.

Giant cell arteritis: Diagnostic difficulties

“…Atherosclerosis is a common pathology in the GCA patient age group, and results in an IMT increase [12]. Various studies have used different IMT cutoff points, yet there is no defined consensus to date [13][14][15][16][17][18]. Giant cell arteritis on the axillary artery ultrasound is characterized by the specific "slope sign" -the nature of increased IMT thickness transition to normal thickness [19].…”

Circulating PD-1hiCXCR5- and CXCR5+ CD4 T cells are elevated in patients with newly diagnosed Giant Cell Arteritis and predict relapse

“…The IMT was measured in the longitudinal view in the wall distal to the US probe and in the area with greatest wall thickness without an atherosclerotic appearance. The cutoff values for IMT, measured from the luminal side of the intima to the adventitia, were: ≥0.34mm for the frontal and parietal branches, ≥0.42mm for the common trunks of the temporal arteries, and ≥1mm for the axillary, subclavian and carotid arteries [20–23]. We defined a CDUS as positive when at least one artery showed a halo sign and its thickness was equal to or greater than the established cut-off point.…”

“…Patients with isolated involvement of the carotid arteries were excluded to improve the diagnostic validity of the study. An increased IMT in carotid arteries namely lacks the specificity for GCA compared with atherosclerosis as recently shown [23]. Upon diagnosis, patients were classified into US defined phenotypes: cranial (C) large vessel (LV) or mixed (Mx).…”

“…³0.34mm for the frontal and parietal branches, ³0.42mm for the common trunks of the temporal arteries, and ³1mm for the axillary, subclavian and carotid arteries [20][21][22][23]. We defined a CDUS as positive when at least one artery showed a halo sign and its thickness was equal to or greater than the established cut-off point.…”