Asymmetrical Planar Folded Dipole Antennas for Human Body MRI at 7 T

This study presents a new asymmetrical planar folded dipole (APFD) coil, tailored for 7 T human body magnetic resonance imaging (MRI). Compared to traditional fractionated dipole (FD) antennas, the APFD coil is designed to enhance transmit efficiency, homogeneity, and specific absorption rate (SAR) management. Through rigorous numerical simulations and experimental validations, the APFD coil has exhibited superior transmit field uniformity and efficiency. Moreover, it has achieved a remarkable decrease in peak SAR<inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$_{10\,\text {g}}$ </tex-math></inline-formula> values, reducing them by up to 31%. Imaging results from in vivo torso scans demonstrate the coil’s effectiveness, providing expanded imaging area coverage and consistent illumination of anatomical structures, along with good channel decoupling. These advancements are targeted at overcoming the electromagnetic (EM) challenges at radio frequencies inherently posed in ultrahigh-field (UHF, <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\ge 7$ </tex-math></inline-formula> T) MRI, presenting a viable option for safer and more efficient human body imaging. Although further research is necessary to evaluate its clinical applicability across various anatomical areas and patient demographics, the APFD coil represents a step forward in radio frequency (RF) coil technology, opening new possibilities for improved diagnostic capabilities and patient care in UHF MRI.