Age-Related Vascular Changes Affect Turbulence in Aortic Blood Flow

Figures

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  Figure 1. Schematic overview of hemodynamic analysis using 4D Flow MRI. 4D Flow MRI acquires the turbulence and velocity data from the magnitude and phase images, respectively. Regional analyses were performed in four different anatomical regions (AAo, ascending aorta; DAo, descending aorta; SAA, suprarenal abdominal aorta; IAA, infrarenal abdominal aorta).

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  Figure 2. Schematic description of global and regional analysis of flow velocity and TKE. (A) Global velocity and TKE analysis. A time point for Vmax, whole was chosen to analyze peak Vavg, whole and peak Vmax, whole. Peak TKEtotal, whole was separately assessed in different time frame with the velocity parameters. (B) Regional velocity and TKE analysis. Depending on the region of analysis, separate time frames for Vmax were selected to assess peak Vavg and Vmax in each aortic segment. Separate time frames for each aortic segement were also selected for estimating regional peak TKEtotal. Note that Vmax, IAA and TKEtotal, IAA were omitted from (B) for clarity.

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  Figure 3. Graphical summary of velocity and TKE parameters in each subject group. Velocity and TKE mapping of a representative subject of each group are shown, with the mean ± SD of the group. Upper panel shows the regional average velocity (without parentheses, m/s) and maximum velocity (within parentheses, m/s). Bottom panel shows the regional peak total TKE (without parentheses, mJ) and the regional peak maximum TKE (within parentheses, J/m3). Data are analyzed as described in Figure 2. Red solid lines indicate the region boundaries. *Indicates significant difference with p < 0.001 compared to the young group.

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  Figure 4. Scatter plot of the relationship between regional peak total TKE and maximum Reynolds number. Pearson correlation coefficient, r, between the regional peak total TKE and the maximum Reynolds number were calculated for each region. Red solid line indicates the regression line. r and p in each plot indicate the Pearson product-moment correlation coefficient and statistical significance. Note that the peak total TKE in the whole aorta (TKEtotal, whole) was plotted against the Reynolds number in the ascending aorta (Remax, AAo) as the Reynolds number is highest in the ascending aorta (as shown in Table 2).