Cardiac and respiratory motion extraction for MRI using pilot tone-a patient study

Area of Science:

• Cardiovascular Imaging
• Medical Signal Processing
• Magnetic Resonance Imaging (MRI)

Background:

• Accurate monitoring of respiratory and cardiac motion is crucial for high-quality cardiovascular MRI.
• Existing methods for motion artifact reduction and signal extraction can be complex or invasive.
• Pilot Tone (PT) is an integrated system within MRI coils for signal generation.

Purpose of the Study:

• To evaluate the accuracy and reliability of cardiac and respiratory signals derived from Pilot Tone (PT).
• To compare PT's performance against established methods like ECG and BioMatrix (BM) respiratory sensors.
• To assess PT's potential for real-time motion monitoring in cardiovascular MRI.

Main Methods:

• Twenty-three patients undergoing cardiovascular MRI were scanned using a real-time (RT) cine sequence.
• Pilot Tone (PT) signals were extracted and processed retrospectively for cardiac and respiratory information.
• Synchronous recording of ECG and BioMatrix (BM) respiratory sensor data for comparative analysis.

Main Results:

• PT demonstrated a strong positive correlation (0.95 ± 0.09) with image-derived respiratory motion, outperforming BM (0.72 ± 0.24).
• PT cardiac signal trigger jitter was a median of 21.8 ms, with mean absolute difference in cardiac cycle duration <5% for 21/23 patients.
• No significant dependence of PT delay or jitter on patient BMI or cardiac cycle duration was observed.

Conclusions:

• Pilot Tone (PT) is a reliable method for extracting both respiratory and cardiac signals in cardiovascular MRI.
• PT offers a promising, non-invasive alternative for real-time motion monitoring during clinical scans.
• The findings support the integration of PT for improved image quality and diagnostic accuracy in cardiac MRI.