Magnetic resonance imaging with respiratory gating: techniques and advantages

Area of Science:

• Medical Imaging
• Biophysics

Background:

• Respiratory motion is a significant artifact source in thoracic and abdominal MRI.
• Effective respiratory gating is crucial for high-quality imaging in these regions.

Purpose of the Study:

• To evaluate practical approaches for respiratory gating in MRI.
• To assess methods for signal acquisition, gating sequences, and examination time reduction.
• To determine the impact of gating on image quality and relaxation time measurements.

Main Methods:

• Compared three respiratory signal acquisition devices; a displacement transducer belt was most effective.
• Implemented two pulse-gating modes and combined cardiac-respiratory gating.
• Evaluated spin-conditioned vs. triggered gating modes using phantoms and volunteers.

Main Results:

• Spin-conditioned respiratory gating outperformed triggered gating.
• Examination time increased by 30-50% with voluntary breath holds, vs. 200-400% with uncontrolled breathing.
• Respiratory gating substantially reduced variability in relaxation time measurements for displaced organs.

Conclusions:

• Respiratory gating is a practical technique to enhance contrast and spatial resolution in MRI of the chest and abdomen.
• Spin-echo images, especially with short repetition times, benefit significantly from respiratory gating.
• Gating improves the reliability of quantitative MRI measurements affected by motion.