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Contactless cardiac gating at 0.55T using high-amplitude pilot tone with interference cancellation (HAPTIC)
Bilal Tasdelen1, Ecrin Yagiz1, Baran R Cinbis1
1Ming Hsieh Department of Electrical and Computer Engineering, University of Southern California, Los Angeles, California, USA.
Magnetic Resonance in Medicine
|April 14, 2025
Summary
Contactless cardiac gating at 0.55T is now possible using HAPTIC, a novel pilot tone (PT) method. This technique overcomes limitations of previous PT methods at lower field strengths, enabling easier MRI workflows.
Area of Science:
- Medical Imaging
- Biophysics
- Cardiovascular Technology
Background:
- Current pilot tone (PT) methods struggle to detect subtle cardiac motion at low magnetic field strengths (<1.5T).
- Accurate cardiac gating is crucial for MRI, but existing methods can be cumbersome or unavailable on lower-field systems.
Purpose of the Study:
- To develop and validate a contactless cardiac gating technique using pilot tone at 0.55T.
- To overcome the limitations of existing PT methods in detecting weak cardiac signals at lower field strengths.
Main Methods:
- A novel method called HAPTIC (High-Amplitude Pilot Tone with Interference Cancellation) was developed.
- HAPTIC utilizes high-amplitude PT for improved sensitivity and External Dynamic InTerference Estimation and Removal (EDITER) for noise reduction.
- Performance was assessed in healthy volunteers and patients with arrhythmia, comparing HAPTIC gating to electrocardiogram (ECG).
Main Results:
- HAPTIC successfully extracted cardiac PT signals at 0.55T with low gating jitter (<9 ms).
- The technique demonstrated robust tracking of cardiac and respiratory phases during real-time MRI.
- Feasibility was shown for accurate cardiac gating even in patients with cardiac arrhythmia.
Conclusions:
- HAPTIC enables the first demonstration of contactless cardiac gating at 0.55T using any PT variant.
- This innovation can simplify clinical workflows and offers a solution for mid- and low-field MRI scanners lacking integrated physiological monitoring.
