Modeling and In Vitro Measurement of a Compact Antenna for Intravascular Catheter Tracking and Imaging System

Abstract

Technological advancements in tracking and imaging have necessitated the development of a compact and efficient antenna for instrumental devices. Currently, intravascular coils have low-quality resolution and limited functionalities, which demand magnetic resonance (MR) antennas with improved sensitivity, quality factor, high-resolution imaging, versatility, and safety. This article presents a miniature antenna for an intravascular device in an MR imaging (MRI) system that offers a high-quality factor, a high signal-to-noise ratio (SNR), precise visibility, orientation with respect to the B0 field, a low specific absorption rate (SAR), and the smallest volume. The optimization of the antenna was carried out using both the finite-element method and the finite-difference time-domain method. Additionally, a fabricated prototype was integrated into an electrophysiological (EP) catheter model. The performance of the fabricated prototype was evaluated in a saline solution and heart to measure the reflection coefficient both in bent and flat conditions. The MR antenna exhibit satisfactory performance with a quality factor of 28 and an SNR of 58, indicating optimum sensitivity and high-quality imaging. Furthermore, the effect of the metallic and nonmetallic surfaces of the catheter on the proposed antenna is analyzed. The catheter-integrated MR antenna creates a homogeneous magnetic field and maintains persistent visibility of the catheter during MRI. The sum of B1 field strengths ( Σ B1) and average B1 field in the region of interest (ROI) was improved by approximately 61% and 12%, respectively. Finally, safety considerations were taken into account when analyzing the performance of the MR antenna.