There has long been interest in performing simultaneous or interleaved multinuclear studies [1-5]. The development of hyperpolarized MRI and MRS has brought remarkable improvement in SNR, and the importance of magnetization management may motivate true simultaneous rather than interleaved multinuclear studies. Quantitative MRI and MRS also provides motivation, though interleaved acquisitions may be sufficient for many applications. This work reports initial results at developing a broadband spectrometer, capable of simultaneous acquisition from multiple nuclei, and supporting array coil acquisition from each nuclei. Results are shown from simultaneous ¹H/²H imaging on a 1.0T scanner, as well as simultaneous ¹H/²H/²³Na spectroscopy on a 4.7T scanner. This should be of particular interest in dynamic experiments where the limited time may not favor ‘conventional’ interleaved experiments [1, 6, 7], or simply as an alternative to the switching required in interleaving.A broadband NMR spectrometer (Fig. 1) was assembled for true simultaneous multinuclear transmit and receive. The pulse sequencer employed a National Instruments PCI-6363 DAQ card to provide analog outputs and digital control. NI LabVIEW was used as the programming environment. Each gradient amplifier used a single Apex PA12A operational amplifier, providing a 10 to 90 rise time to 15 Amps of approximately 200 microseconds. For the spectroscopy experiments, simultaneous hard pulse excitation at multiple frequencies was accomplished using an Analog Devices 9959 DDS, a four channel 500 MSPS DDS with 10 bit amplitude and phase control. For shaped pulses, two independently modulated RF pulses can be generated at two frequencies using an AD9915 DDS controlled by a high speed DIO card (National Instruments PCI-6733). The RF pulses are combined and fed to a conventional broadband amplifier. A triple nuclei coil was assembled from three nested, single band T/R coils. The three frequencies were separated following the RF amplifier using a transmission line duplexing arrangement. Single tuned coils were used for excitation, with the signals split after the amplifier. All signals were directly digitized using an Ultraview 16 bit, 250 MS/s/ch, 4 channel digitizer card (Ultraview Corp, Berkeley, CA). Postprocessing was done offline in Matlab, allowing spectral widths for the three nuclei to be independently selected during reconstruction. For comparison, the same coil was used with a Varian Inova console to acquire single spectra from each nuclei separately. The unused coils were simply open-circuited.Simultaneously excited and acquired ¹H and ²H acquisitions obtained from the spectrometer are shown in Fig. 2. SNR is low due to the long TR of distilled water in the ¹H image, and actually higher in the ²H image (in the central region) due to the lower resolution and thicker slice, a result of the lower Larmor constant for ²H. All parameters were identical except for the output power at each frequency. The ¹H and ²H signals present in each echo were simultaneously digitized by the broadband receiver card. The nominal resolution at ¹H is 120 mm FOV/128 = 0.94 mm. The ²H image, due to the difference in the Larmor constant has a resolution of 0.94x6.5 = 6 mm. Following demodulation, the separated k-space data sets were zero-filled in to a 256x256 matrix prior to reconstruction. Figure 3 compares ¹H, ²³Na and ²H spectra obtained separately from the Varian scanner as reference to simultaneously acquired on our spectrometer. The simultaneously acquired spectra were acquired two ways, with each coil connected to a separate digitizer channel and then with each coil connected through a 4-way combiner, following preamplification, to a single digitizer channel. The latter approach was of interest because if enables arrays to be used at each frequency. When combined, additional preamplification was used on the ²H and ²³Na channels, but not ¹H. We believe this caused the lower SNR on the ¹H channel (the noise floor was below the digitizer noise). However, it was interesting that the SNR on ²H and ²³Na was significantly better than on our Varian scanner, indicating a problem in that scanner. Commonly available electronics hardware now enables construction of custom broadband spectrometers that can support simultaneous multinuclear imaging and spectroscopy. It would be preferable to have separate narrow band power amplifiers rather than one broadband amplifier, but the approach of using a single amplifier proved sufficient and greatly lowers cost and complexity. There are certainly challenges in pulse sequence design that are easier to overcome with sequential acquisition, but this abstract demonstrates the ability to excite and acquire multiple nuclei simultaneously. Because the system has four channels, it will support array detection at multiple frequencies.