Assessment of Abdominal Aorta Diameter on Contrast-enhanced Computed Tomography: A MDCT-based Observational Study

Introduction: Average size of the abdominal aorta is less than 3 cm which variates with time. The increase in abdominal aortic dimensions more than 3 cm can result in the presence of ectasia which can further convert into an aneurysm. The expansion rate can also lead to aortic dissection and rupture. Its increasing dimensions can influence to give rise to numerous other abdominal aortic conditions and be fatal due to the aortic wall stress. Monitoring the variation in the abdominal aorta is now possible with the various advancements in imaging techniques including Computed Tomography (CT). Aim: To measure the Anteroposterior (AP) and Right-Left (RL) diameters of the abdominal aorta on Contrast-enhanced Computed Tomography (CECT) abdomen and to analyse its variation with age and gender. Materials and Methods: A cross-sectional observational study was conducted in the Department of Radiodiagnosis at KS Hegde Charitable Hospital, Deralakatte, Mangaluru, Karnataka, India. The duration of the study was 11 months, from April 2020 to March 2021. A total of 81 patients referred for CECT abdomen divided into two age groups of 20-40 years and 41- 80 years. The scan was performed using 16-slice Multidetector Computed Tomography (MDCT). On the reconstructed axial images, the abdominal aortic diameters were measured at the level of T12-L1. The non parametric Mann-Whitney U test was used to compare the RL and AP diameters with respect to age groups. Unpaired t-test was used to compare the RL and AP diameters with respect to gender. Paired t-test was used to compare AP diameter on contrast and non contrast scans. Results: The mean age of study participants was 47±14.83 years and were divided into two age groups between 20-40 years and 41-80 years. Out of the 81 cases, 31 (38%) were in the age group of 20-40 and 50 (62%) were in the age group of 41-80 years. There was a significant increase in the AP and RL abdominal aortic diameter with age (p-value <0.001) and also males were found to have significantly higher abdominal aorta diameter than females (p-value <0.001) in both the age groups of 20-40 and 41-80 years. Also, the abdominal aorta diameter measurements on Non Contrast Computed Tomography (NCCT) and CECT abdomen showed no notable difference. Conclusion: The present study concluded that, there was a remarkable variation in the diameter of the abdominal aorta with age and gender. Besides, the abdominal aorta diameter measurements on NCCT and CECT abdomen showed no notable difference.