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|Year : 2014 | Volume
| Issue : 1 | Page : 57-60
Evaluation of normal abdominal aortic diameters in the Indian population using computed tomography
A Jasper1, G Harshe1, SN Keshava1, G Kulkarni1, E Stephen2, S Agarwal2
1 Department of Radiology, Christian Medical College, Vellore, Tamil Nadu, India
2 Department of Vascular Surgery, Christian Medical College, Vellore, Tamil Nadu, India
|Date of Submission||28-Apr-2013|
|Date of Decision||08-Sep-2013|
|Date of Acceptance||22-Nov-2013|
|Date of Web Publication||14-Mar-2014|
Department of Radiology, Christian Medical College, Vellore, Tamil Nadu
Source of Support: None, Conflict of Interest: None
Objectives: The aim of this study was to establish normal diameters for the suprarenal and infrarenal abdominal aorta measured at T12 and L3 vertebral levels in the Indian population and to study the variation in aortic diameters with age, sex, height, weight, body mass index (BMI), and body surface area (BSA). Materials and Methods: One hundred and forty-two patients who underwent helical contrast-enhanced computed tomography (CT) scans of the abdomen for non-cardiovascular reasons were recruited.. The mean internal diameters of the suprarenal and infrarenal abdominal aorta (maximum anteroposterior and transverse diameter) were measured at T12 and L3 vertebral levels and tabulated according to various age groups for both men and women. Pearson correlation coefficient was used to evaluate the correlation between aortic diameters, height, weight, BSA, and BMI. Results: The mean diameters of the suprarenal and infrarenal abdominal aorta measured at T12 and L3 vertebral levels, in men were 19.0 ± 2.3 and 13.8 ± 1.9 mm and in women 17.1 ± 2.3 and 12.0 ± 1.6 mm, respectively. The aortic diameter progressively increased in caliber with increasing age of the patients and was smaller in women than men. A significant positive correlation was found in men between the suprarenal and infrarenal aortic diameters and weight, BSA, and BMI. In women, this correlation was significant in the infrarenal aorta but not in the suprarenal aorta. Conclusion: We obtained a set of normal values for the abdominal aorta in the Indian population. The aortic diameters correlated with age, gender, and body size of the patients as seen with previously published data in the Western population. A brief comparison of data between Indian and Western population showed that the values obtained were less than published elsewhere and hence, this should be considered while formulating intervention protocols.
Keywords: Abdominal aortic diameter, computed tomography, Indian population
|How to cite this article:|
Jasper A, Harshe G, Keshava S N, Kulkarni G, Stephen E, Agarwal S. Evaluation of normal abdominal aortic diameters in the Indian population using computed tomography. J Postgrad Med 2014;60:57-60
|How to cite this URL:|
Jasper A, Harshe G, Keshava S N, Kulkarni G, Stephen E, Agarwal S. Evaluation of normal abdominal aortic diameters in the Indian population using computed tomography. J Postgrad Med [serial online] 2014 [cited 2020 Feb 26];60:57-60. Available from: http://www.jpgmonline.com/text.asp?2014/60/1/57/128813
| :: Introduction|| |
Knowledge of the normal aortic diameter in Indians would be useful in management of patients presenting with aortic aneurysms. There is paucity of Indian data on the aortic diameter according to which clinical decisions regarding management of aortic aneurysms i.e., whether to follow up the patients, institute medical therapy or to go for surgery can be made. Most of the data available in literature is based on Western demographic data and treatment in India is still guided by the aortic sizes mentioned in them.
Anecdotal discussions and presentations made at various vascular surgery and interventional radiology meetings made it apparent that the diameter of the aorta in the Indian population is smaller than that of the Western population and therefore treatment protocols for intervention are likely to be different. Criteria for management decisions would change if normal aortic diameters vary significantly in Indian population as opposed to elsewhere.
Ours is a preliminary study using computed tomography (CT), attempting to establish normal diameters for abdominal aorta at different vertebral levels in the Indian population and to study the variation in aortic diameter according to age, sex, BSA, height, body weight, and body mass index (BMI).
| :: Materials and Methods|| |
All CT scans of the abdomen were performed using a 6-slice multidetector CT (MDCT) scanner (Brilliance 6, Philips Healthcare, Cleveland, OH, USA). Contrast scans were acquired after an antecubital intravenous injection of 80-100 ml of a nonionic contrast medium containing 300 mg/ml iodine. The injection rate was 1.5-3 ml/s. The helical CT scan was performed with a delay of 20-25 s after starting the injection. Images were reviewed by scrolling on PACS workstation (Centricity 3.31, GE Healthcare, Barrington, IL).
A prospective study was performed after receiving approval from the Institutional Review Board and written informed consent from patients. Consecutive adult patients, above 20 years of age undergoing helical contrast-enhanced CT scans of the abdomen for non-cardiovascular reasons were included.
Those with large abdominal masses distorting the aorta and preventing accurate measurement of aortic diameters, those with known cardiovascular risk factors like Marfan's syndrome, Ehler-Dahnlos syndrome, vasculitis, those with significant cardiac disease, and other congenital aortic anomalies were excluded. The maximum anteroposterior diameter and the maximum transverse diameter (internal diameters) of the suprarenal and infrarenal abdominal aorta were measured at T12 and L3 vertebral levels[ [Figure 1] using the software available in the CT console and the mean values were obtained.
|Figure 1: Sagittal reconstruction of the abdominal aorta on a contrastenhanced computed tomography (CT) abdomen with the corresponding axial CT sections at T12 and L3 vertebral levels|
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Image acquisition and interpretation
Statistical analysis was performed using a computer software package (Statistical Package for Social Sciences (SPSS) 16.0). The correlation between height, weight, BMI, and body surface area (BSA) and aortic diameter was analyzed using the Pearson correlation coefficient. The DuBois formula (BSA = 0.007184 × W 0.425 × H 0.725 ) was used to calculate the BSA. Independent sample t-test was used to compare the aortic diameters in men and women. All analyses were done at 5% significance.
| :: Results|| |
The mean age was 46.4 ± 12.3 in men and 45.4 ± 13.7 in women [Table 1]. Fifty-three percent of the subjects were men. The mean diameters of the suprarenal and infrarenal abdominal aorta for all men and women are given in [Table 2]. There was a significant positive correlation between the age of the patient and the average aortic diameter in the supra and infrarenal aorta measured at T12 and L3 vertebral levels in both men and women
At all vertebral levels, there was a significant difference in the average diameter of the aorta in men and women (P < 0.001), however, the difference was not significant when all the age groups were considered separately [Table 3].
|Table 3: Mean abdominal aortic diameters of the various age groups measured on axial CT sections|
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The mean BSA was 1.65 m 2 in men and 1.49 m 2 in women. In men, there was significant positive correlation between BSA and aortic diameter in the supra and infrarenal abdominal aorta. In women, a significant positive correlation was seen between BSA and the infrarenal abdominal aortic diameter only [Table 4] and [Figure 2]a and b.
|Table 4: Correlation between BSA and aortic diameter in males and females|
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A positive correlation was seen between height and the suprarenal and infrarenal aortic diameters in men and women, however, it was of significance statistically only in women for the infrarenal aorta.
A significant positive correlation was seen between the aortic diameter at T12 level which corresponds to the suprarenal aorta and the weight and BMI in men. In women, although there was a positive correlation it was not statistically significant. Infrarenal aortic diameters correlated positively with weight and BMI in both men and women.
| :: Discussion|| |
The 2010 guidelines for the diagnosis and management of aortic disease recommends imaging modalities that do not involve ionizing radiation, like magnetic resonance imaging, which can replace CT in the appropriate clinical scenario.  Our subjects were undergoing CT scans of the abdomen for other indications and were not subjected to additional ionizing radiation for the purpose of this study.
In our study, the mean diameter of the suprarenal abdominal aorta in men (measured at T12 vertebral level) was 19 ± 2.3 mm and in women was 17.1 ± 2.3 mm. The mean diameter of the infrarenal aorta measured at L3 level was 13.8 ± 1.9 mm in men and 12.0 ± 1.6 mm in women. Values of 16-18 mm in women and 19-21 mm in men were the normal reference values for infrarenal aortic diameters in Australia.  Average infrarenal abdominal aortic diameters in patients from the Framingham Heart Study in men were 19.3 and 16.7 mm, respectively.  In a study in the Turkish population by Sariosmanoglu et al., which measured aortic diameters in 596 patients, the mean subdiaphragmatic aortic diameter was 18 ± 3 mm in females and 19 ± 4 mm in males. At the bifurcation level, the mean aortic diameter was 15 ± 3 mm in females and 16 ± 4 mm in males.  A necropsy study of 645 subjects aged 19-97 years, in Brazil by da Silva et al., showed that the mean diameter of the infrarenal aorta in men and women was 1.7 cm and in those more than 70 years was 1.8-2.0 cm.  A Swedish population-based MRI study in men and women more than 70 years obtained values for the upper limit of normal aortic diameter as 3.0 cm in men and 2.7 cm in women.  The observed abdominal aortic diameters in our study were less than that obtained in the various studies available in the Western population.
A difference of 1.9 mm in the suprarenal and 1.8 mm in the infrarenal aortic diameters (P-value <0.05) was seen between men and women. This gender difference is similar to that of previous studies. ,,,, With increasing age, there was a progressive increase in mean aortic diameters in both men and women in both the suprarenal and infrarenal aorta. Almost all the previous studies which took age into consideration while measuring aortic diameters found a similar correlation. ,,,
This study was limited by the number of subjects included in our study. However, the correlation with age, gender, and BSA that we obtained were comparable with previously published larger studies. ,, As this was performed in a single center, it may not be representative of the varying ethnic and racial groups in our country. A larger population-based multicentric study, ideally in normal subjects would be beneficial in obtaining more representative values.
| :: Acknowledgement|| |
We would like to thank Ms. Tunny Sebastian, Lecturer, Department of Biostatistics, CMC Vellore for her contribution to the statistical analysis and Dr. Pradeep John Promod for his editorial assistance.
| :: References|| |
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[Figure 1], [Figure 2]
[Table 1], [Table 2], [Table 3], [Table 4]
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