Towards contact-free motion sensing technique at low-field MRI using beat pilot tone

To improve the image quality in low field, the conventional method is to repeat scanning many times, and finally increase the SNR by averaging multiple imaging data. Unfortunately, long scan time can make images highly susceptible to motion artifacts. A recent contact-free motion detection technology Beat Pilot Tone (BPT) improves the sensitivity compared with Pilot Tone (PT) and is not limited by Larmor frequency. We introduce BPT in a 0.25T low-field MRI system, and successfully reduce the motion artifacts while improving SNR by binning the continuously acquired data into different motion states in image domain and k-space via BPT signal.