This MRI Facility houses a new Siemens 32-channel 3T Skyra (Siemens Healthcare, Germany) and a Philips 32-channel 3T Ingenia (Philips Medical Systems, The Netherlands). Both scanners have wide bores and are equipped with MR-compatible technologies for conducting experiments with human subjects. The Philips system has been used by up to ten labs over the course of five years; it will be phased out later this year and the Siemens will be used for most if not all current and future scanning. In addition to high resolution images of brain anatomy (structural MRI or sMRI), both scanners support functional MRI (fMRI) and diffusion imaging of long-range white matter tracts, and thus adequately support all UNR neuroimaging needs.
"Functional" MRI (fMRI) differs from high-field strength "structural" MRI (sMRI) by its ability to image beyond anatomical detail into the functional workings of the brain, how the brain thinks, and where it all takes place. The specific type of fMRI being utilized in these research projects is known as "BOLD" fMRI, more scientifically known as "neurovascular coupling". As important and exciting as all of this is, there are also other techniques that fall under the general heading of fMRI as well.
Fractional anisotropy (FA), featuring directionally color-coded fiber tracts, can map out deep white matter axonal pathways which connect all of the eloquent sites in the brain identified with the BOLD fMRI. The FA maps can easily be converted into Diffusion Tensor Images (DTI) in which the exquisite neuroanatomy of the connections in the brain are displayed and studied.
MR Spectroscopy (MRS) and Perfusion MRI (pMRI) also fit under the heading of fMRI. MRS deals with in vivo examination of hydrogen spectra in selected regions of brain, while pMRI allows assessment of the amount of blood flowing into and through any portion of brain anatomy.
The Siemens 32-channel 3T Skyra system is fully equipped (as of Fall 2019) for advanced neuroimaging, and in many ways surpasses the capabilities of the Philips Ingenia system. This Siemens system has a fast gradient system that provides high-speed spatial encoding, a 64-channel data acquisition system with digital wireless technology to improve SNR and temporal stability, and a dual-channel RF transmitter system for reduction of dielectric effects, and more flexible RF pulse design. The gradient rise time (200 mT/m/ms), peak gradient strength (45 mT/m per axis), and duty cycle (100% using full gradient strength on all three axes) are the highest specifications in the industry for whole-body systems. Also, the gradients have a balanced geometric design that results in less acoustic noise generation. Every hardware and software option that Siemens offers for neuroimaging is installed on this MRI system. Parallel imaging capabilities in one and two-dimensions enable EPI acquisitions at higher temporal resolution and with less geometric distortion. In addition, a Master Research Agreement with Siemens Healthcare makes available advanced "works-in-progress" pulse sequences for EPI and structural neuroimaging to deal with specific technical challenges.
The Siemens system is equipped with fMRI-presentation hardware, screen and response pads. It is also equipped with a vPixx eye-tracking system. The TRACKPixx3 MRI/MEG is a 2 kHz eye/gaze-tracking solution compatible with MRI and MEG environments. The TRACKPixx3 is versatile, supporting both monocular and binocular tracking with a single mechanical configuration. The TRACKPixx3 does not require a dedicated PC to process eye images and generate gaze information; all image processing is performed within the TRACKPixx3 hardware. Gaze data can be logged within the TRACKPixx3 and retrieved by the testing PC with a simple low-latency USB interface. The TRACKPixx3 video feed can be accessed directly through a console display for real-time visualization and adjustment of the tracker. A scene camera can be connected to the tracker to monitor the experiment. These video feeds can also be accessed through the USB interface for remote control of the TRACKPixx3.
The Philips Ingenia 3.0T system comes with a dStream digital broadband architecture and a channel independent RF technology, which results in an up to 40% more SNR. dStream digitizes the signal right in the coil, eliminating noise influences typical of analog pathways, to capture the MR signal without predistortion or compression. A fiber-optic connection from the coil to the image reconstructor enables lossless broadband data transmission. This Ingenia 3.0T system has a higher order shim function which offers advanced shimming capabilities to obtain improved image quality in field-sensitive applications and techniques such as single-voxel spectroscopy, chemical shift imaging, single-shot EPI and balanced FFE. This Ingenia 3.0T system features high performance whole body, non-resonant, self-shielded gradient technology with new amplifiers that deliver high peak and slew rates for the demanding requirements of the latest and emerging clinical imaging techniques. The Quasar Dual gradient system provides industry leading performance specifications for peak strength and slew rate with a dual mode capability that optimizes advanced applications requiring very high peak mode capabilities. The maximum gradient amplitudes and slew rates corresponding to the dual mode are 80 mT/m, 100 mT/m/ms and 40 mT/m, 200 mT/m/ms respectively. This Ingenia 3.0T system has a multiple RF sources, which adapts the RF signals to suit each individual patient. This results in a faster scan, enhanced image uniformity/consistency, over a broader range of applications. This Ingenia 3.0T system features MultiBand SENSE which allows you to use state-of-the-art acceleration factors in the brain by simultaneously exciting multiple slices. Due to a shorter minimum TR for fMRI, larger anatomical coverage or higher temporal resolution can be used. In the DWI/DTI sequences larger anatomical coverage or higher number of diffusion directions can be acquired. With MultiBand SENSE, fMRI and DTI exams can be performed with high speed and high resolution, simultaneously.
This Ingenia 3.0T system is equipped with a Multi-nuclear spectroscopy (MNS) system, which provide the ability to perform 13C, 31P, 7Li, 23Na, 19F and other nuclei spectroscopy and imaging. The multiple RF amplifiers in this system includes two 18 kW solid-state 1H channel narrowband amplifier and one 4 kW broadband (10-130 MHz) Multi-nuclear amplifier.
This Ingenia 3.0T system has a bore diameter of 60 cm and provides a full-size 50 cm field-of-view. Analog to digital signal conversion on the coil, 70cm bore, multi-transmit, Omega HP Gradients (slew rate 200 mT/m/ms, maximal gradient strength 45 mT/m), unlimited RF channels, fMRI-presentation hardware, screen and response pads.