Thoracic aorta - dilated or not?

Objectives. Knowledge of normal aortic diameters is important in the assessment of aortic disease. The aim of this study was to determine normal thoracic aortic diameters. Design. 77 patients undergoing computed tomography of the thorax were studied. The diameter of the thoracic aorta was measured at three levels in the ascending aorta and at three levels in the descending aorta. The diameter was studied in relation to age, sex, weight and height. Results. We found that aortic diameter is increasing with increasing age. Even sex and BMI influence the aortic diameter but to a lesser extent than age. The upper normal limit for ascending aorta can be calculated with the formula D( mm) = 31 + 0.16(star)age and for descending aorta with the formula D(mm) = 21 + 0.16(star)age. Thus a 20-year-old person has an upper normal limit for ascending aorta of 34 mm and an 80-year-old person has a limit of 44 m. Conclusions. The thoracic aortic diameter varies with age, sex and body weight and height. The strongest correlation can be seen with age. Age should therefore be taken into consideration when determining whether the thoracic aorta is dilated or not.