High-Resolution Imaging With a Miniaturized Dual-Channel iMRI Antenna for Interventional Applications

The development of compact, multichannel antennas for interventional devices has become essential due to advancements in imaging technology. Currently, interventional micro-coil and interventional magnetic resonance imaging (iMRI) antennas have poor imaging resolution and limited capabilities, necessitating dual-channel iMRI antennas with improved imaging performance, radio frequency safety, sensitivity, and versatility. In this article, a compact dual-channel antenna for iMRI at 128 and 298 MHz is presented, offering dual-band characteristics, improved imaging performance, lower specific absorption rates (SARs), reasonable decoupling performance, precise visibility, and a smaller volume. The proposed dual-channel iMRI antenna was miniaturized and optimized using meandered strips in the radiating patch and ground plane, along with a shorting pin and tuning and matching capacitors. Effective decoupling between the two antennas within a limited space was achieved by adding long strips and capacitors. Ex vivo measurements of the reflection and coupling coefficients were performed using an iMRI antenna integrated with an electrophysiological (EP) catheter in the heart and a saline solution. Dual-channel iMRI antennas integrated with catheters exhibit homogeneous B<inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$_{1}^{-}$ </tex-math></inline-formula> field distributions and maintain persistent catheter visibility during 3 and 7 T MRIs. The single channel B<inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$_{1}^{-}$ </tex-math></inline-formula> field strength (<inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\Sigma B_{1}^{-}$ </tex-math></inline-formula>) and average B<inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$_{1}^{-}$ </tex-math></inline-formula> field exhibit notable improvement of about 68% and 15%, respectively, and the dual channel improved by approximately 85% and 57% at 128 MHz. Finally, safety concerns were also considered when evaluating the performance of the dual-channel iMRI antenna.