3D velocity quantification in the heart: Improvements by 3D PC-SSFP

Abstract

Purpose: To test whether a 3D imaging sequence with phase contrast (PC) velocity encoding based on steadystate free precession (SSFP) improves 3D velocity quantification in the heart compared to the currently available gradient echo (GE) approach. Materials and Methods: The 3D PC-SSFP sequence with 1D velocity encoding was compared at the mitral valve in 12 healthy subjects with 3D PC-GE at 1.5T. Velocity measurements, velocity-to-noise-ratio efficiency (VNReff), intra- and interobserver variability of area and velocity measurements, contrast-to-noise-ratio (CNR), and artifact sensitivity were evaluated in both long- and short-axis orientation. Results: Descending aorta mean and peak velocities correlated well (r2 = 0.79 and 0.93) between 3D PC-SSFP and 3D PC-GE. At the mitral valve, mean velocity correlation was moderate (r2 = 0.70 short axis, 0.56 long axis) and peak velocity showed good correlation (r2 = 0.94 short axis, 0.81 long axis). In some cases VNReff was higher, in others lesser, depending on slab orientation and cardiac phase. Intra- and interobserver variability was generally better for 3D PC-SSFP. CNR improved significantly, especially at end systole. Artifact levels did not increase. Conclusion: 3D SSFP velocity quantification was successfully tested in the heart. Blood-myocardium contrast improved significantly, resulting in more reproducible velocity measurements for 3D PC-SSFP at 1.5T. © 2009 Wiley-Liss, Inc.