Magnetic Resonance Imaging with a Multichannel Optically Pumped Magnetometer

Ultra-low field (ULF) magnetic resonance imaging (MRI) is a promising method for anatomical imaging with various advantages over conventional MRI such as low cost and low weight. Previously, multichannel parallel ULF MRI was realized only with multichannel superconducting quantum interference devices (SQUIDs), but the cryogenic operation is a serious drawback. We aim to develop a more practical parallel ULF MRI based on a multichannel optically pumped magnetometer (OPM) and multiple flux transformers. The OPM is the most sensitive cryogen-free magnetic sensor in a broad range of frequencies from kHz to MHz. In this talk, we describe the basic principle and the design of our ULF MRI system. We also present our recent progress on the reduction of crosstalk between sensing channels and the development of a single-module multichannel OPM.