A triple tuned coil and front-end for simultaneous multinuclear MR imaging and spectroscopy
Chung-Huan Huang1, Hongli Dong2, Stephen E. Ogier2, Chenhao Sun2, and Steven M. Wright2

1Electrical and Computer Engineering, Texas A&M University, College Station, TX, United States, 2Texas A&M University, College Station, TX, United States


There are several ways to implement simultaneous acquisition for multiple nuclei. A single-port triple tuned coil is the simplest structure and has the best potential for integration into multiband arrays. This abstract demonstrates an approach to acquire three nuclei (1H/23Na/2H) MRS simultaneously by using a home-built broadband spectrometer with a triple tuned coil. The broadband spectrometer front-end is capable of providing separate gains to each of studied nucleus where signal sensitivity variation is large and can reduce data throughput load by using undersampling techniques while still maintaining similar performance as a Varian Inova system.


Simultaneous acquisition of multiple nuclear species is of interest 1-3 for quantitative MRI/MRS and hyperpolarized multinuclear acquisition. Today, most of simultaneous acquisitions are limited to dual nuclei or separate coils are used for different nuclear species which makes the receiver configuration more complex 4,5. Additionally, it is desirable to apply different gains to different nuclei to best use digitizer’s limited dynamic range when performing simultaneous multinuclear acquisition. In this work, a single-port triple tuned coil was designed to test with our broadband spectrometer front-end where the coil can simplify the structure without changing inputs for different nuclei and the front-end allows different gains to be applied at each of signal paths. Moreover, the front-end utilizes one preamplifier where conventional approach may use up to three preamplifiers. This directly decreases the cost and the complexity of multinuclear experiments. Results are shown from single frequency image 1H, 23Na, and 2H with the tripled tuned coil as well as simultaneous 1H/23Na/2H MR spectroscopy on a 4.7 T scanner using undersampling techniques.


A multi-frequency matching and tuning section was designed based on multiple pole circuits 6 where the triple tuned coil was designed as a transmit/receive surface coil based on a butterfly geometry 7 shown in Fig 1. The aim of using this geometry is to provide two modes from the coil, a butterfly mode and a loop mode, but with only a single port so that it can be tested with the proposed broadband front-end. The butterfly mode is only resonant at the 1H frequency, while the loop mode is tuned for the X-nuclei. Having two modes can ease the design on the matching and tuning network because only a double-resonant circuit, a capacitor in series with a parallel combination of an inductor and a capacitor, is necessary for the X-nuclei while a single-tuned circuit is needed for proton. With such configuration, the coil has the ability to provide less coupling and interdependence in tuning over multiple single nuclear coils. Three nuclei images were obtained separately by using a Varian Inova system without switching inputs to demonstrate the convenience when acquiring different nuclei signals.

A broadband NMR spectrometer was assembled previously in Magnetic Resonance Systems Lab in Texas A&M University for true simultaneous multinuclear transmit and receive 2. For this work, the transmit pulses were generated by a separate device from the receive console. Now, NI LabVIEW is used as the programming environment to control the pulse sequencer for up to three RF frequencies in an integrated desktop which greatly simplifies the setup. Simultaneous acquisition front-end for three nuclei were also developed based on a flexible RF filtering front-end 8 to provide separate gains to each of three nuclei with proper filtering and combine filtered signals back into one output channel for digitization. For comparison, simultaneous MR spectra were acquired with the broadband spectrometer while single frequency MR spectra were obtained with the Varian.

Results and Discussion

The triple tuned coil was simultaneously tuned to better than -24 dB at 1H/23Na/2H. Single nuclear excited and acquired images with the Varian are shown in Fig. 2, demonstrating that the coil is able to acquire multinuclear images without switching inputs. Simultaneous MRI images were not obtained due to limitations on the broadband spectrometer, i.e. shaped RF pulse generation is presently limited to two channels. However, simultaneous MRS were carried out with the broadband spectrometer with a pulse and acquire sequence to show the capability of simultaneous multinuclear acquisition. Fig 3. compares 1H, 23Na and 2H spectra obtained by the single excitation with the Varian as a reference to simultaneous acquisition acquired by our broadband spectrometer. The broadband spectrometer presents a lower SNR at 1H and we believe this may due to a wide bandwidth of the digitizer (700 Mhz), resulting in out of band noise aliasing down to Nyquist region. However, all three nuclei present comparable SNRs between single and simultaneous acquisition.


This study allows us to apply a single-port triple tuned coil when performing simultaneous acquisition with flexible RF filtering front-end in the broadband spectrometer. This greatly simplifies the structure of the receiver and eases the tuning over separated coils as well as reducing experiment setup time for acquisition of multiple nuclei. More importantly, single frequency images and simultaneous MRS with the proposed structure provide an approach to simultaneous multinuclear imaging. There are certainly challenges to design a multiband array coils, but this abstract initially presents the ability to acquire multiple nuclei simultaneously by utilizing one input channel of the digitizer where others are available for multiband arrays.


No acknowledgement found.


1. S. E. Ogier, et al. RF Power Considerations for Simultaneous Multi-Nuclear MRI/MRS. 25th ISMRM (2017).

2. S. E. Ogier, et al. A Broadband Spectrometer for Simultaneous Multinuclear Magnetic Resonance Imaging and Spectroscopy. 24th ISMRM (2016).

3. M.R. Smith, et al. In Vivo Imaging and Spectroscopy of Dynamic Metabolism Using Simultaneous 13C and 1H MRI. IEEE TBME. 59, 45-49 (2012).

4. M. Meyerspeer, et al. Simultaneous and interleaved acquisition of NMR signals from different nuclei with a clinical MRI scanner. MRM. 76, 1636-1641 (2016).

5. H. Kovacs, et al.. Parallel NMR spectroscopy with simultaneous detection of 1H and 19F nuclei. Magnetic Resonance in Chemistry 54, 543-543 (2016).

6. B.L Beck. Double-Tuned Surface Coils. in eMagRes. (2011).

7. P. Cao, et al. (1) H-(13) C independently tuned radiofrequency surface coil applied for in vivo hyperpolarized MRI. MRM. 76, 1612-1620 (2016).

8. C. Huang, et al. Flexible RF Filtering Front-End For Simultaneous Multinuclear MR Spectroscopy. in 2018 40th IEEE(EMBC) 1368-1371 (2018).


Figure 1. Single-port triple tuned coil geometry (left) and physical photograph top view (right). The triple tuned coil is a transmit/receive coil with one single feeding cable. Proton is fed at bottom of center conductor which results in a butterfly mode (blue arrows). X-nuclei are fed at bottom of rim conductor which generates a loop mode (red arrow). In this way, proton is decoupled from the X-nuclei since fields will be orthogonal at ROI. For X-nuclei, dual resonant circuits are used to generate two poles for 23Na and 2H decoupling.

Figure 2. Diagram of imaging phantom (Left) with varying concentration of 23Na and 2H. Only tube 2 contains 50 % distilled water and is aligned with center conductor. 1H (middle left), 23Na (middle right), and 2H (right) images were obtained by using a single frequency GRE sequence with the single-port triple tuned coil and a Varian Inova System. Due to low signal intensity of 23Na image, 16 averages were applied to 23Na while 1H and 2H were 1 average, respectively. The images present a convenient approach to acquire multinuclear MRI with the triple tuned coil without a need to switching inputs.

Figure 3. Comparison of single and simultaneous acquisition spectra for 1H/23Na/2H. All spectra are normalized to its peak with phase correction. Single acquisitions were performed using a Varian Inova system (left column) whereas simultaneous acquisitions were obtained using the home-built broadband spectrometer (right column). All three nuclei SNRs present comparable values between two systems.

Proc. Intl. Soc. Mag. Reson. Med. 27 (2019)