Magnetic resonance scanner Siemens MAGNETOM 7T
In summer 2007, a third magnetic resonance scanner was installed at the Institute. Its magnet with an open bore of 60-centimeter inner diameter produces a field of 7 tesla — which is 140,000 times stronger than the magnetic field of planet earth. With covers, it is roughly 3.6 meters long and weighs more than 34 metric tons. The cryostat holds approximately 1,750 liters of liquid helium to cool the superconducting coil of niobium-titanium alloy permanently to 4,2 kelvins. For shielding, the magnet is installed within an iron box of 10 × 5.7 × 5.7 meters weighing 362 tons. Outside this iron shield, the stray field is efficiently reduced, and the 0.5 millitesla contour is well-contained within the elliptical building housing the scanner.
Two gradient systems are available for spatial encoding—a whole-body system producing up to 45 milliteslas per meter with a minimal ramp time of 225 microseconds or, alternatively, a head-gradient set capable of generating gradients of 80 millitesla per meter within 200 microseconds. The resonance frequency for hydrogen imaging is 300 megahertz. Thirty-two radiofrequency channels are available for receiving magnetic resonance signals. A special feature is the installation of an array of 8 independent transmit channels, which are sufficiently broad banded for magnetic resonance with most biologically relevant nuclei other than hydrogen.