Prevalence of Incidentally Identified Thoracic Aortic Dilations: Insights for Screening Criteria

Background: Systematic screening for ascending thoracic aortic aneurysms and dilations does not exist currently with unknown prevalence and diagnostic yields. We evaluated the prevalence of ascending thoracic aortic dilation. Methods: Computed tomography scans including the chest in adult patients carried out during 2016 were reviewed at our institution. Aortic dilation was defined as the ascending thoracic aorta diameter >= 4.0 cm, with sensitivity analyses using height-indexed values and thresholds of 3.5, 4.25, and 4.5 cm. The prevalence of aortic dilation was evaluated by age and sex. Potential diagnostic yield along the continuum of age threshold was calculated by sex. Results: Of the 5662 scans from unique patients, the prevalence of aortic dilation was 2.1% overall, 3.2% for males and 0.9% for females. Patients with aneurysms were significantly older (70.2 +/- 9.9 vs 58.3 +/- 16.4 years, P < 0.001) and more likely to be male (81.0% vs 54.2%, P < 0.001). The highest diagnostic yield of aneurysm >= 4.5 cm in females occurred at the age threshold of >= 73 years, with the yield of 0.5%. The highest diagnostic yield of aneurysm >= 4.5 cm in males occurred at age >= 84 years, with the yield of 5.7%. In males, the diagnostic yields at age thresholds of >= 50, >= 60, and >= 70 years were 1.3%, 1.6%, and 2.2%, respectively. Conclusions: Aortic dilation was identified in 2.8% of individuals with age >= 50 years. In females, aneurysm was uncommon. In males, there was an incremental increase in the diagnostic yield with age. Male patients with age >= 50 years may be the demographic group with a high prevalence of dilation.