Modeling and In Vitro Measurement of a Compact Antenna for Intravascular Catheter Tracking and Imaging System
Shahzeb Hayat, Abdul Basir, Hyoungsuk Yoo
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 functionality, which demand magnetic resonance (MR) antennas with improved sensitivity, quality factor, high-resolution imaging, versatility, and safety. This paper presents a miniature antenna for an intravascular device in a magnetic resonance imaging (MRI) system that offers a high-quality factor, high signal-to-noise ratio (SNR), precise visibility, orientation with respect to the B <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0</sub> field, low specific absorption rate, and the smallest volume. The optimization of the antenna was carried out using both the finite element method and the finite difference time domain. Additionally, a fabricated prototype was integrated into an electrophysiological 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 SNR of 58, indicating optimum sensitivity and high-quality imaging. Furthermore, the effect of the metallic and non-metallic 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 <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">B</i> <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">1</sub> field strengths (Σ <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">B</i> <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">1</sub> ) and average B <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">1</sub> field in the region of interest was improved by approximately 61% and 12%, respectively. Finally, safety considerations were taken into account when analyzing the performance of the MR antenna.