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

PURPOSE

To measure the effects of using time-resolved (TR) versus time-averaged (TA) ventricular segmentation on four-dimensional flow-sensitive (4D flow) magnetic resonance imaging (MRI) kinetic energy (KE) calculations.

MATERIALS AND METHODS

Right (RV) and left (LV) ventricular KE was calculated from 4D flow MRI data acquired at 3.0T in 10 healthy volunteers and five subjects with cardiac disease using TR and TA segmentation. KE was calculated from the mass of blood within the ventricles multiplied by the velocities squared. Differences in TR and TA KE and interobserver variability were quantified with Bland-Altman analysis.

RESULTS

In healthy volunteers, peak systolic RV KE (KE ) were 4.89 ± 1.49 mJ using TR and 5.53 ± 1.62 mJ using TA segmentation (P = 0.016); peak systolic LV KE (KE ) were 3.29 ± 0.96 mJ and 4.16 ± 1.26 mJ (P = 0.005). Peak diastolic KE were 3.33 ± 0.90 mJ (TR) and 3.61 ± 1.12 mJ (TA) (P = 0.082), while peak diastolic KE were 4.90 ± 1.49 mJ and 5.31 ± 1.59 mJ (P = 0.044). In patient volunteers, peak systolic KE were 4.34 ± 3.78 mJ using TR and 4.88 ± 3.98 mJ using TA segmentation (P = 0.26); peak systolic KE were 4.39 ± 4.21 mJ and 4.36 ± 3.84 mJ (P = 0.91). Peak diastolic KE were 3.34 ± 2.08 mJ (TR) and 4.05 ± 1.12 mJ (TA) (P = 0.08), while peak diastolic KE were 4.34 ± 5.11 mJ and 4.06 ± 3.47 mJ (P = 0.75). Interobserver differences in KE were greater for TR than TA calculations; bias ranged from 3 ± 30% for TA peak systolic KE to 36 ± 30% for TR peak diastolic KE .

CONCLUSION

Although qualitatively similar, KE values calculated through TA segmentation were consistently greater than TR KE, with differences more pronounced during systole and in the LV.

LEVEL OF EVIDENCE

2 J. Magn. Reson. Imaging 2017;45:821-828.