Removable second-order trap for common-mode current suppression in multi-nuclear MRI cabling

Purdue University, West Lafayette IN

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Abstract

PROJECT SUMMARY/ABSTRACT The growing availability of high-field magnetic resonance imaging (MRI) scanners has reignited the pursuit of in vivo metabolomics approaches to investigate human physiology, disease, and treatment. In particular, multinuclear magnetic resonance spectroscopy (MRS) data reveal physiological and biochemical details inaccessible to standard proton-based scans. For example, 13C MRS can elucidate rates of glucose, glycogen, and lipid metabolism, while 31P spectra may profile high-energy phosphates. While the ability to run non-proton sequences is inherent in most clinical and research MRI scanners, the obligatory multinuclear radiofrequency (RF) coil hardware is less readily available and often custom-developed. Operating at both the proton (1H) and second-nucleus Larmor frequencies, dual-tuned RF coils must also include myriad trap circuits along the cabling path to suppress common-mode currents, essential for maintaining signal fidelity and, more importantly, preventing severe surface burns on the patient. Nearly all cable trap implementations for RF coils involve direct soldering to a cable's conductive shield, increasing the risk of introducing a failure mode. A clear opportunity exists for streamlining cable trap deployment with easily-fabricated, non-destructive, removable and reusable designs. This proposal aims to overcome previous manufacturing and cost limitations by designing and providing the community open-source 3D-printable cable traps designs. This work entails developing both single-frequency and multinuclear cable traps, validating their functionality with bench and MRI/MRS experiments, writing an open-source software program to calculate optimal geometric parameters and electrical component characteristics for any given MRS scenario, and providing this new research technology to the community as open-source design and script files. The proposed single-frequency device will generate broadly-applicable technology for proton-based MRI, while the proposed multinuclear device will demonstrate utility with a focus specific to facilitating metabolomics research. Three specific aims outlined to accomplish this work: 1) Design and construct add-on cable traps to provide common-mode current suppression at a single frequency; 2) Design and construct add-on cable traps to simultaneously provide common-mode current suppression at two frequencies; 3) Produce software to calculate geometric and electromagnetic design parameters for end users and release all design files to the research community.