# Low-complexity decoupling of multi-frequency arrays for magnetic resonance imaging and spectroscopy using operational amplifiers

> **NIH NIH R21** · TEXAS ENGINEERING EXPERIMENT STATION · 2020 · $171,220

## Abstract

PROJECT SUMMARY/ABSTRACT
The broad objective of this proposal is to develop a new approach to the design of array coils for multi-
nuclear imaging and spectroscopy. The approach will avoid the use of resonant circuits for impedance
matching and for providing ‘preamplifier decoupling’ using specialized low-impedance preamplfiiers.
Instead, the proposal uses high-impedance, low-noise, operational amplifiers to operate series tuned coils
at multiple frequencies. Only one capacitive element is envisioned on each coil, which is relatively non-
specific, but will compensate for the reactance of the coil. Standard techniques can enable that one circuit
element to compensate at multiple frequencies, enabling one array coil element to be used at multiple
frequencies.
The motivation for this project, broadly speaking, is the rapidly increasing utilization of MRI and MRS of
nuclei other than hydrogen. In virtually every case of non-1H acquisitions, it is desirable to also be able to
image hydrogen, and often in simultaneous or interleaved fashion. Simultaneous multi-nuclear MRI and
MRS has been suggested since the earliest days of the field, and is recently reemerging due to the
development of hyperpolarized MR, high-field magnets, and the increasing availability of multi-channel
broadband receivers. Hyperpolarized MRI is enabling spectroscopic imaging of other nuclei, in turn
providing a wealth of emerging opportunities to characterize in vivo metabolic events. However, the short
lifetime of the polarization is driving the need for array coils to provide imaging acceleration. Multi-
frequency array coils are extremely complex using current technology. The approach presented here will
lower the cost and complexity of array coil design, removing an entry barrier to research in multi-nuclear
MRI and MRS.
The specific goal of this project is to investigate and optimize the interface of RF coil arrays to low-noise
preamps to implement this new multi-frequency array design method. Three aims are defined; first to
evaluate the noise figure of each of several interface approach, second to assess the decoupling provided
by the best approaches from aim 1, and then third to compare coil arrays built using conventional
approaches to a multi-frequency array built using the best performing approach from aims 1 and 2. All
design procedures will be built into MATLAB scripts and made publicly available, along with all specifics of
the test arrays used in this project to assist other researchers to design multi-frequency arrays.

## Key facts

- **NIH application ID:** 9951055
- **Project number:** 5R21EB028516-02
- **Recipient organization:** TEXAS ENGINEERING EXPERIMENT STATION
- **Principal Investigator:** Steven M Wright
- **Activity code:** R21 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2020
- **Award amount:** $171,220
- **Award type:** 5
- **Project period:** 2019-07-01 → 2022-04-30

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/9951055

## Citation

> US National Institutes of Health, RePORTER application 9951055, Low-complexity decoupling of multi-frequency arrays for magnetic resonance imaging and spectroscopy using operational amplifiers (5R21EB028516-02). Retrieved via AI Analytics 2026-05-23 from https://api.ai-analytics.org/grant/nih/9951055. Licensed CC0.

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