7T Human

GE Healthcare Discovery MR950 7T Human MRI

Supported by the State of Wisconsin, a GE high-field, actively shielded, 7T whole-body imaging system is installed and has been operational at the MCW CIR since July 2014.

This 7T scanner enhances shared use of the centralized MRI resources, enriches ongoing and promotes new research, fosters a cooperative and interactive research environment, and stimulates multidisciplinary approaches to imaging research. MCW has provided a strong institutional commitment to the 7T imaging facility and its maintenance.

Overview

The GE 7T MR950 system is a 90-cm bore, investigational human research MRI system. It uses the latest 7T actively shielded magnet technology, which substantially reduces the footprint of our 7T system. Only two other systems using this technology are currently available at the University of Minnesota and the University of Iowa.

Our system acquired its first human images in June 2014. This system is housed in the Department of Biophysics in the MACC Fund Building and is part of the Daniel M Soref Imaging Research Facility.

The GE MR950 platform utilizes state-of-the-art gradient, receiver, and RF transmission technology.  This system is capable of performing 8-channel transmission and 32-channel signal reception.

We currently are equipped with the following hardware on this system:

  • Nova Medical 32-channel head (Rx)
  • Nova Medical 2-channel head (Tx/Rx)
  • Noval Medical 8-channel head (Tx)

The following hardware has been ordered or will be available by summer 2016:

  • Resonance Research ultra-high order shim insert (up to fifth-order spherical harmonic shimming)

Additional Details

Magnet design and shim subsystem. The MR950 contains a 7T actively shielded magnet and superconducting shims manufactured by Varian (Magnex); weighs 38 tons (excluding cryogens); and has a clear bore size of 900 mm, with first-, second-, and third-order superconducting shims. The resistive shim subsystem has a total of six zero- and first-order shim coils and two second-order shim coils with 4-A maximum current shim drivers (amplifiers). The magnet enclosure/facade and patient-handling subsystem include a dockable (removable, mobile) table, vibration isolation, acoustic damping, and a physiological acquisition controller.

Gradient system. The gradient system includes an XRMb gradient coil driven by eXtreme gradient driver (XGD) amplifiers (1600 V and 600 A). The gradient coil cooling system is capable of extracting more than 25 kW of heat from the coils. The gradient system provides a maximum amplitude per axis of 50 mT/m, a maximum slew rate per axis (T/m/sec) of 200 T/m/sec, and full eddy current compensation including Bo and cross-terms.

RF amplifier. For exciter, receiver, and power RF subsystems, the transmitter is configurable from 70 to 300 MHz for 1 H imaging and multinuclear imaging/spectroscopy experiments. The RF power amplifier comprises 10×1-kW modules and is configurable as 2×4-kW or 8×1-kW Tx channels. The receiver has the high linearity of an MR750 receiver system, supporting imaging and spectroscopy of 1H, 31P, 23Na, and 13C with an X-nucleus and 1H decoupler kit. Provided are 32 independent 1-H receivers and a 32-channel receiver coil.

Host computing platform, reconstruction engine, and software. Version 23.0-based software will include all commercially available pulse sequences, spectroscopy, and imaging options, nominally equivalent in form and function to the MR750 platform.

 


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