Thin film based semi-active RF marker desing for interventional MRI devices

Abstract

Compared to the other imaging modalities Magnetic Resonance Imaging (MRI) system has many advantages. There is a great demand to carry out interventional cardiovascular procedures under MRI scanner. However, the lack of visible markers and MRI compatible interventional instruments and devices, is the main problem for realizing clinical applications with MRI guidance. In order to provide widespread usage of MRI for endovascular operations, commercial catheters and guidewires must be manufactured by considering many performance criteria including visualization, miniaturization, exibility and safety. In this thesis, clinical grade biocompatible polymers and metals were used to manufacture clinical grade MRI compatible RF markers. Proposed RF marker was deposited on a non planar biocompatible catheter surface by physical vapor deposition (PVD) technique using cylindrical laser cut shadow masks, which kept the overall device pro le low. The presented fabrication approach is highly reproducible, and versatile, allowing variation of micro coils, capacitors, and conducting layer designs that are crucial for tuning the speci c resonant frequency of a RF marker. In adddition to aforementioned work, an orientation independent simulation model was developed and validated to obtain a reliable method for evaluating the designed RF marker structures in a MRI environment. Finite Element Method (FEM) simulations were carried out for di erent RF coil designs to make the computational analysis of their electrical and magnetic characteristics in COMSOL Multiphysics program.|Keywords : Semi active RF marker, RF coil, RF receiver antenna, thin lm based techniques, RF heating, FEM simulations, congenital heart diseases.