4D flow MRI of aortic blood flow parameters in healthy volunteers: Sex- and age-specific analysis

PURPOSE: Four-dimensional (4D) flow MRI enables comprehensive assessment of aortic hemodynamics, but normative values remain limited, especially for Asian populations. This study aimed to establish age- and sex-specific normative values for flow-related parameters in healthy Korean adults. METHODS: Seventy-seven healthy volunteers (aged 20-79 years) underwent 4D flow MRI. Hemodynamic parameters-velocity, viscous energy loss, normalized vorticity, and helicity-were quantified in the ascending aorta (AAo), aortic arch (AoA), and descending aorta (DAo). RESULTS: Significant sex differences were found for velocity in the AAo (p < 0.001) and viscous energy loss across all segments (p < 0.05), while normalized vorticity and helicity showed no sex-related differences. In viscous energy loss, males had higher values than females in the AAo (2.84 ± 1.05 vs 2.22 ± 0.60 mW, p = 0.017), AoA (0.74 ± 0.37 vs 0.42 ± 0.19 mW, p = 0.001), and DAo (4.78 ± 1.82 vs 3.32 ± 1.55 mW, p = 0.002). Most parameters demonstrated age-related declines, especially in the DAo. Strongest correlations with age were seen for velocity (r = -0.725, p < 0.001) and viscous energy loss (r = -0.745, p < 0.001). Positive helicity showed sex-specific aging trends, with the strongest correlations in the DAo for men and the AoA for women. Negative helicity showed the strongest correlation in the DAo in both sexes. CONCLUSIONS: This study established age- and sex-specific normative values for aortic hemodynamic parameters in healthy Korean adults using 4D flow MRI. While sex differences were limited, most flow parameters declined with age.