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

Area of Science:

• Cardiovascular Imaging
• Magnetic Resonance Imaging
• Hemodynamics

Background:

• Accurate 3D velocity quantification in the heart is crucial for diagnosing cardiovascular conditions.
• Current gradient echo (GE) based phase contrast (PC) sequences have limitations in cardiac imaging.
• Steady-state free precession (SSFP) sequences offer potential advantages for cardiac MRI.

Purpose of the Study:

• To evaluate a novel 3D phase contrast steady-state free precession (PC-SSFP) sequence for cardiac velocity quantification.
• To compare the performance of 3D PC-SSFP against the established 3D phase contrast gradient echo (PC-GE) technique.
• To assess improvements in velocity measurements, efficiency, reproducibility, and image quality.

Main Methods:

• A 3D PC-SSFP sequence with 1D velocity encoding was implemented and compared to 3D PC-GE at 1.5T.
• 12 healthy subjects were scanned, with measurements performed at the mitral valve and descending aorta.
• Evaluated parameters included velocity measurements, velocity-to-noise-ratio efficiency (VNR(eff)), observer variability, contrast-to-noise-ratio (CNR), and artifact sensitivity.

Main Results:

• Good correlation of mean and peak velocities was observed between 3D PC-SSFP and 3D PC-GE in the descending aorta.
• At the mitral valve, moderate to good correlation for mean and peak velocities was found, with better reproducibility for 3D PC-SSFP.
• Significant improvement in CNR was noted for 3D PC-SSFP, particularly at end systole, without increased artifact levels.

Conclusions:

• 3D PC-SSFP is a viable and effective technique for cardiac velocity quantification.
• The improved blood-myocardium contrast of 3D PC-SSFP leads to more reproducible velocity measurements.
• This sequence represents a significant advancement for 3D cardiac MRI, especially at 1.5T.