Aortomesenteric angle: A contrast-enhanced computed tomography analysis of respiratory phase and visceral fat impact

Objectives: The objective of this study was to evaluate the relationship between the aortomesenteric angle at end- inspiration and end-expiration and its variation rate with several anthropometric parameters. Material and Methods: Sagittal reconstructed computed tomography (CT) images of 59 patients who underwent contrast-enhanced CT at end-inspiration and end-expiration between 2015 and 2020 were reviewed. All these patients underwent dynamic contrast CT during both inspiration and expiration for adrenal venous sampling purposes. Two experienced radiologists measured the aortomesenteric angle during both end-inspiration and end-expiration, and its variation rate. Pearson's or Spearman's correlation analysis was used to assess correlations between the angle or variation rate and height, weight, body mass index (BMI), visceral fat, subcutaneous fat, and diaphragm motion. Results: The aortomesenteric angle was significantly larger at end-expiration (88.65 +/- 25.15, 95% confidence interval [CI] 82.09-95.20) compared to end-inspiration (62.22 +/- 21.90, 95% CI 56.51-67.93, P < 0.001). The aortomesenteric angles at both end-inspiration and end-expiration correlated significantly with weight, BMI, visceral fat, and subcutaneous fat. The strongest correlation was between aortomesenteric angle and visceral fat at both end-inspiration (r = 0.523, P < 0.001) and end-expiration (r = 0.546, P < 0.001). The variation rate correlated only with diaphragm motion (r = 0.550, P < 0.001). Conclusion: The aortomesenteric angle at end-expiration was significantly larger than at end-inspiration, with the strongest correlation found between the angle and visceral fat.