title: Hybrid monopole/loop coil array for human head MR imaging at 7T.
abstract: The monopole coil and loop coil have orthogonal radiofrequency (RF) fields and thus are intrinsically decoupled electromagnetically if they are laid out appropriately. In this study, we proposed a hybrid monopole/loop technique which could combine the advantages of both loop arrays and monopole arrays. To investigate this technique, a hybrid RF coil array containing 4 monopole channels and 4 loop channels was developed for human head MR imaging at 7T. In vivo MR imaging and g-factor results using monopole-only channels, loop-only channels and all channels of the hybrid array were acquired and evaluated. Compared with the monopole-only and loop-only channels, the proposed hybrid array has higher SNR and better parallel imaging performance. Sufficient electromagnetic decoupling and diverse RF magnetic field (B1) distributions of monopole channels and loop channels may contribute to this performance improvement. From experimental results, the hybrid monopole/loop array has low g-factor and excellent SNR at both periphery and center of the brain, which is valuable for human head imaging at ultrahigh fields.
authors.affiliation: Key Laboratory of Nuclear Radiation and Nuclear Energy Technology, Institute of High Energy Physics, Chinese Academy of Sciences, Beijing 100049, China ; Beijing Engineering Research Center of Radiographic Techniques and Equipment, Beijing 100049, China ; State Key Laboratory of Brain and Cognitive Science, Beijing MRI Center for Brain Research, Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101, China.
authors.forename: Xinqiang
authors.initials: X
authors.lastname: Yan
authors.affiliation: Key Laboratory of Nuclear Radiation and Nuclear Energy Technology, Institute of High Energy Physics, Chinese Academy of Sciences, Beijing 100049, China ; Beijing Engineering Research Center of Radiographic Techniques and Equipment, Beijing 100049, China.
authors.forename: Long
authors.initials: L
authors.lastname: Wei
authors.affiliation: State Key Laboratory of Brain and Cognitive Science, Beijing MRI Center for Brain Research, Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101, China ; China and Beijing Institute for Brain Disorders, Beijing 100053, China.
authors.forename: Rong
authors.initials: R
authors.lastname: Xue
authors.affiliation: Department of Radiology and Biomedical Imaging, University of California San Francisco, San Francisco, California 94158, USA ; UCSF/UC Berkeley Joint Graduate Group in Bioengineering, San Francisco, California 94158, USA.
authors.forename: Xiaoliang
authors.initials: X
authors.lastname: Zhang
keywords: Hybrid; RF coil; array; decouple; loop; monopole; parallel imaging; ultrahigh field MRI