Aortic size assessment by noncontrast cardiac computed tomography: normal limits by age, gender, and body surface area.
OBJECTIVE
To determine normal limits for ascending and descending thoracic aorta diameters in a large population of asymptomatic, low-risk adult subjects.


BACKGROUND
Assessment of aortic size is possible from gated noncontrast computed tomography (CT) scans obtained for coronary calcium measurements. However, normal limits for aortic size by these studies have yet to be defined.


METHODS
In 4,039 adult patients undergoing coronary artery calcium (CAC) scanning, systematic measurements of the ascending and descending thoracic aorta diameters were made at the level of the pulmonary artery bifurcation. Multiple linear regression analysis was used to detect risk factors independently associated with ascending and descending thoracic aorta diameter and exclude subjects with these parameters from the final analysis. The final analysis groups for ascending and descending thoracic aorta included 2,952 and 1,931 subjects, respectively. Subjects were then regrouped by gender, age, and body surface area (BSA) for ascending and descending aorta, separately, and for each group, the mean, standard deviation, and upper normal limit were calculated for aortic diameter as well as for the calculated cross-sectional aortic area. Also, linear regression models were used to create BSA versus aortic diameter nomograms by age groups, and a formula for calculating predicted aortic size by age, gender, and BSA was created.


RESULTS
Age, BSA, gender, and hypertension were directly associated with thoracic aorta dimensions. Additionally, diabetes was associated with ascending aorta diameter, and smoking was associated with descending aorta diameter. The mean diameters for the final analysis group were 33 +/- 4 mm for the ascending and 24 +/- 3 mm for the descending thoracic aorta, respectively. The corresponding upper limits of normal diameters were 41 and 30 mm, respectively.


CONCLUSIONS
Normal limits of ascending and descending aortic dimensions by noncontrast gated cardiac CT have been defined by age, gender, and BSA in a large, low-risk population of subjects undergoing CAC scanning.
Departments of Imaging, CSMC Burns & Allen Research Institute, Cedars-Sinai Medical Center, University of California at Los Angeles, USA.
Arik
A
Wolak
Heidi
H
Gransar
Louise E J
LE
Thomson
John D
JD
Friedman
Rory
R
Hachamovitch
Ariel
A
Gutstein
Leslee J
LJ
Shaw
Donna
D
Polk
Nathan D
ND
Wong
Rola
R
Saouaf
Sean W
SW
Hayes
Alan
A
Rozanski
Piotr J
PJ
Slomka
Guido
G
Germano
Daniel S
DS
Berman
D000328:Adult; D000367:Age Factors; D000368:Aged; D000369:Aged, 80 and over; D001011:Aorta / Q000473:pathology*; D001013:Aorta, Thoracic / Q000000981:diagnostic imaging*; D001018:Aortic Diseases / Q000000981:diagnostic imaging* / Q000209:etiology; D001027:Aortography / Q000379:methods*; D001830:Body Surface Area; D002114:Calcinosis / Q000000981:diagnostic imaging; D003324:Coronary Artery Disease / Q000000981:diagnostic imaging; D003920:Diabetes Mellitus / Q000000981:diagnostic imaging; D005260:Female; D006801:Humans; D006973:Hypertension / Q000000981:diagnostic imaging; D016014:Linear Models; D008297:Male; D008875:Middle Aged; D012016:Reference Values; D018570:Risk Assessment; D012307:Risk Factors; D012737:Sex Factors; D012907:Smoking / Q000009:adverse effects; D014057:Tomography, X-Ray Computed