Left and right ventricular kinetic energy using time-resolved versus time-average ventricular volumes.

Area of Science:

• Cardiovascular Imaging
• Biomedical Engineering
• Medical Physics

Background:

• Four-dimensional flow (4D flow) magnetic resonance imaging (MRI) enables quantitative assessment of blood flow dynamics.
• Kinetic energy (KE) calculations are crucial for understanding ventricular function.
• Segmentation methods, time-resolved (TR) versus time-averaged (TA), can influence these calculations.

Purpose of the Study:

• To compare the effects of TR and TA ventricular segmentation on 4D flow MRI kinetic energy (KE) calculations.
• To evaluate differences in KE measurements between healthy volunteers and cardiac patients.
• To assess interobserver variability in KE calculations.

Main Methods:

• 4D flow MRI data were acquired at 3.0T in 10 healthy volunteers and 5 cardiac patients.
• Right (RV) and left (LV) ventricular KE were calculated using both TR and TA segmentation methods.
• Differences and interobserver variability were analyzed using Bland-Altman analysis.

Main Results:

• Time-averaged (TA) segmentation consistently resulted in higher KE values compared to time-resolved (TR) segmentation.
• These differences were more pronounced during systole and in the left ventricle (LV).
• Interobserver variability for LV KE was greater with TR than TA segmentation.

Conclusions:

• While qualitatively similar, TA segmentation leads to higher ventricular KE values than TR segmentation in 4D flow MRI.
• The choice of segmentation method impacts KE calculations, particularly during systole and for the LV.
• These findings have implications for the standardization and interpretation of 4D flow MRI-derived hemodynamic parameters.