The hemodynamic parameters from 4D flow datasets have shown promising diagnostic value in different cardiovascular pathologies. However, the behavior of these parameters can be affected when the 4D flow data are corrupted by respiratory motion. The purpose of this work was to perform a quantitative comparison between hemodynamic parameters computed from 4D flow cardiac MRI both with and without respiratory self-gating. We considered 4D flow MRI data from 15 healthy volunteers (10 men and 5 women, 30.40 ± 6.23 years of age) that were acquired at 3T. Using a semiautomatic segmentation process of the aorta, we obtained the hemodynamic parameters from the 4D flow MRI, with and without respiratory self-gating. A statistical analysis, using the Wilcoxon signed-rank test and Bland–Altman, was performed to compare the hemodynamic parameters from both acquisitions. We found that the calculations of the hemodynamic parameters from 4D flow data that were acquired without respiratory self-gating showed underestimated values in the aortic arch, and the descending and diaphragmatic aorta. We also found a significant variability of the hemodynamic parameters in the ascending aorta of healthy volunteers when comparing both methods. The 4D flow MRI requires respiratory compensation to provide reliable calculations of hemodynamic parameters.
Phase-contrast in areas with a significant fat signal is subject to chemical shift artifacts where the fat signal interferes with the neighboring water signal. The purpose of this work is to present a novel three-point Dixon method that preserves the phase information in water and fat images and combines this method with phase-contrast to obtain water-fat concentration and velocity images from a single acquisition. We validate our method using a numerical phantom and MRI acquired in volunteers. Phase-contrast three-point Dixon and standard methods showed equivalent results comparing different ROIs of the PDFF using NRMSE.
Phase-contrast in areas with a significant fat signal is subject to chemical shift artifacts where the fat signal interferes with the neighboring water signal. The purpose of this work is to present a novel method that combines phase-contrast with T2*-IDEAL water-fat separation to obtain water-fat concentrations and velocity images from a single acquisition. We validate our method using a numerical phantom with different combinations of water-fat concentrations, velocity, and noise, and MRI of a 2D axial section of the neck acquired in volunteers. PDFF comparisons showed a significant agreement between phase-contrast T2*-IDEAL and standard methods.
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