Measurement of aortic diameters and detection of asymptomatic aortic aneurysms in a mass screening program using a mobile helical computed tomography unit.

In a mass chest computed tomography (CT) screening using a mobile helical CT unit, we measured the aortic diameter at three segments to confirm standard values and also attempted to detect any asymptomatic aortic aneurysms. The population screened in the present study consisted of 6971 subjects (3847 men and 3124 women, mean age 60.3 +/- 12.1 years). They underwent a plain chest CT to screen for lung cancer and tuberculosis. The diameters of the ascending and descending aorta were measured at the level of the pulmonary artery bifurcation. The abdominal aorta was measured at the level of the celiac bifurcation, and the mean values for each measurement were calculated. In addition, we attempted to determine whether any correlation exists among aortic diameter, age, and indices of body size and investigated the frequency of asymptomatic aortic aneurysms among the general population. The mean aortic diameter of all three segments was significantly larger in men than in women and increased with age. It also correlated significantly with indices of body size (P < 0.01). A total of 11 subjects (0.16%) had asymptomatic aortic aneurysms (3 ascending, 4 descending, and 4 thoracoabdominal). The aortic diameter in each individual case was greater than the mean aortic diameter +3 standard deviations in each age group. Chest CT screening for lung cancer can thus detect asymptomatic aneurysms through simultaneous aortic measurement.