Structural and functional fetal cardiac imaging using low field (0.55 T) MRI

Area of Science:

• Medical Imaging
• Cardiovascular Imaging
• Fetal Medicine

Background:

• Clinical 0.55T MRI scanners offer potential for fetal cardiac imaging.
• Optimizing imaging sequences is crucial for overcoming low field strength limitations.

Purpose of the Study:

• To assess the feasibility of a 0.55T MRI scanner for comprehensive fetal cardiac imaging.
• To optimize MRI sequences for fetal cardiac structure and function assessment.

Main Methods:

• Optimized balanced steady-state free precession (bSSFP) and phase contrast (PC) sequences using in utero studies.
• Acquired optimized bSSFP, PC, and half-Fourier single-shot turbo spin-echo (HASTE) sequences in 21 late gestation fetuses.
• Performed blood flow measurements in umbilical vein, descending aorta, and superior vena cava using PC sequences and retrospective gating.

Main Results:

• Optimized bSSFP sequences showed a 1.6-fold SNR increase and improved contrast at 0.55T.
• PC sequences achieved increased SNR and reduced scan time, enabling successful blood flow measurements.
• Reconstructions and great vessel segmentations were of good quality, with fetal cardiac structures and vessels consistently visualized.

Conclusions:

• 0.55T MRI is a feasible option for fetal cardiac examination.
• Strategic optimization of sequence parameters effectively compensates for reduced SNR at low field strength.
• The study demonstrated the robustness and reproducibility of low-field MRI for fetal cardiac imaging.