Ultrasound compared to Computed Tomography in identifying thoracic aortic aneurysms in patients with Giant Cell Arteritis

Objectives The objectives of this study were to evaluate the correlation and agreement between ultrasound and computed tomography (CT) in measuring ascending aorta diameter in patients with giant cell arteritis (GCA) and to investigate the development of new ascending aortic aneurysms in patients with newly diagnosed GCA. Methods To achieve the primary objective, we performed a cross‐sectional study including GCA patients evaluated with both ultrasound and CT of the ascending aorta within 6 months of each other. For the second objective, patients with baseline aortic imaging at GCA diagnosis were followed prospectively with new aortic imaging at the end of the follow‐up. A cut‐off of ≥ 40 mm defined an aneurysm in both the ascending and the descending aorta. Results The cross‐sectional study included 140 patients with a total of 169 comparable CT and ultrasound scans and a mean disease duration of 47.8 months (95% CI 42.1‐53.5). A strong positive correlation, as measured by Spearman's rho (r = 0.801, p < 0.001), and a strong agreement, as indicated by an intraclass correlation coefficient (ICC) of 0.849 (p < 0.001), were found between ultrasound and CT. In the prospective follow‐up study, 40 patients were included. Seven (17.5%) developed aneurysms in the ascending aorta in a mean follow‐up time of 54 months (95% CI 43.7‐64.6); all of them suffered large vessel (LV) involvement (2 patients with LV‐GCA and five patients with mixed‐GCA). Conclusion A strong correlation and agreement were observed between ultrasound and CT measurements in assessing the diameter of the ascending aorta in patients with GCA. Ultrasound may be a valuable tool for longitudinal monitoring and screening for aneurysm development. Notably, about 18% of patients developed aortic aneurysms over a mean follow‐up of 4.5 years, underscoring the critical need for regular aortic screening in this population.