Thin film based semi-active resonant marker design for low profile interventional cardiovascular MRI devices

Abstract

The developed RF resonant marker on a clinical grade 5 Fr guiding catheter will enable several interventional congenital heart disease treatment procedures under MRI.

A 20‐gauge active needle design with thin‐film printed circuitry for interventional MRI at 0.55T

“…The mechanical accuracy of the computer numeric control–based electromechanical system showed the fine printing capabilities of the proposed method with ~4 µm resolution (Figure S2B). This technique eliminates the time‐consuming and/or expensive preparations required for alternative microelectromechanical systems‐based fabrication methods 25,39,45,47,49,70 . Moreover, any change in the desired RF antenna geometry can be applied instantaneously by modifying the corresponding part of the software control code without the need for any alterations in the fabrication setup.…”

“…23,24 Semiactive devices (resonant markers) inductively couple with the transmitted RF-energy and excite the surrounding tissue with an amplified flip angle, generating a bright signal on the image. 25,26 Active iMRI devices incorporate electronic components directly connected to the MRI hardware receiver chain to accomplish MRI visibility. 27 RF-receiver coils integrated to the device body can detect nearby hyperintense MRI signal and theoretically exhibit high SNR, allowing unambiguous visualization (profiling) for safe and effective navigation and therapy delivery.…”

“…44 All such characteristics are excessively rigid and impair device miniaturization; indeed, currently there is no commercially available active MRI needle device. Recently, microelectromechanical systems fabrication techniques, including 3D laser lithography, 45,46 aerosol deposition, 47,48 hot embossing, 49 deposition by thermal evaporation, 25 wrapping flexible circuit sheets, 50 and focused beam sputtering, 51 have been used to build RF receiver antenna components as thin-film structures predominantly on planar surfaces. These methods may require detailed preparations and/or a high maintenance infrastructure such as a cleanroom.…”

“…Such needles typically suffer ambiguous tip and shaft visualization, especially at targets such as tissue interfaces and blood vessel margins, which can exhibit magnetic susceptibility artifacts 23,24 . Semi‐active devices (resonant markers) inductively couple with the transmitted RF‐energy and excite the surrounding tissue with an amplified flip angle, generating a bright signal on the image 25,26 …”

Real-Time Control of Active Catheter Signals for Better Visual Profiling During Cardiovascular Interventions Under MRI Guidance

“…It has been shown by several active tracking and imaging coil designs [16], [31], [32], that tuning and/or matching directly at the coil output is also possible. With recent advances in microstructure production, more components could be embedded on the interventional device, such as low profile capacitors [33], [34]. Interface circuits with impedance control have also been demonstrated to reduce RF-induced heating of various interventional active devices [21], [22], [35].…”