A Composite Four-Channel Receive Coil Designed for a 50 mT Mobile Breast MRI Scanner

Low-cost mobile breast magnetic resonance imaging (MRI) systems are of great significance for promoting early screening of breast diseases. However, the low <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${B}_{{0}}$ </tex-math></inline-formula> magnetic field strength of the mobile MRI system and the <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${B}_{{0}}$ </tex-math></inline-formula> direction perpendicular to the human body usually make the design of breast coils difficult. To address these problems, we propose a composite four-channel breast receive coil that consists of breast subcoils and axillary tail subcoils in a 50 mT breast MRI scanner. Breast subcoils were designed as cap-shaped to reduce signal loss caused by extreme <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${B}_{{1}}$ </tex-math></inline-formula>-field inhomogeneity at the breast root. And axillary-tail subcoils were oriented geometrically orthogonal to the breast subcoils, compensating for the imaging void at the axillary tail of the breast subcoil. To solve the decoupling problem of the composite four-channel receive coil, a simulation model of ultralow field decoupling radio frequency (RF) circuit was constructed based on S-parameter analysis. By employing numerical modeling of decoupling components, the challenge of the difficult decoupling of LC components was effectively solved. Phantom imaging results show that the resolution of the 50 mT breast MRI can reach 0.8 mm, with optimal reception and interchannel decoupling performances. In vivo breast imaging results show that the proposed breast coil can observe the whole breast and cardiac silhouette, without signal loss at the breast root. In summary, the four-channel composite breast receive coil proposed in this article will effectively overcome the limitations of 50 mT breast MRI, promoting the application of mobile MRI devices in breast disease screening.