Diameters of the thoracic aorta throughout life as measured with helical computed tomography

Objective: The use of helical computed tomography is well established in the evaluation of the thoracic aorta. Nevertheless, normal diameters and their changes during adult life according to this method are not available. We planned to set up normal diameters for the thoracic aorta of adults obtained by helical computed tomography. Methods: Seventy adults, 17 to 89 years old, without any signs of cardiovascular disease were investigated with helical computed tomography, Aortic diameters were measured at seven predefined thoracic levels. Results: Aortic diameters (mean +/- SD) were 2.98 +/- 0.46 cm at the aortic valve sinus, 3.09 +/- 0.41 cm at the ascending aorta. 2.94 +/- 0.42 cm proximal to the innominate artery, 2.77 +/- 0.37 cm at the proximal transverse arch, 2.61 +/- 0.41 cm at the distal transverse arch, 2.47 +/- 0.40 cm at the isthmus, and 2.43 +/- 0.35 cm at the diaphragm. Men had slightly longer diameters than did women. All diameters increased with age. There was no influence of weight, height, or body surface area. After normalization to the diameter at diaphragmatic level, no statistically significantly influential factor could be detected. Conclusions: This study delineates normal intrathoracic aortic diameters for helical computed tomography, including relationships with sex and age. Pathologic dimensions of the aorta should preferably be provided as percentiles or z scores.