Q: Explain the challenges overcome to put a technology of this capability in place.
A: [Explaining several types of challenges]

Magnet -- Production of a 7T whole-body superconducting magnet was a challenge for the magnet manufacturers. We believe the first system with ultra high field magnet was the 8T magnet at Ohio State University in 1998. 7T followed at University of Minnesota in 1999. Currently there are about twenty-two 7T systems operating in the world plus the OSU 8T and a 9.4T at University of Illinois at Chicago.
Transmit homogeneity of the radiofrequency (RF) field -- An MRI uses radiofrequency similar to local radiostations. Producing a homogeneous RF excitation at 7T is a challenge due to the higher frequency used at 7T (300 MHz). This corresponds to a wavelength smaller than the human brain. The solution appears to be the use of arrays of transmitter coils in similar fashion to the arrays of receivers commonly used in clinical scanners today.

Magnetic shielding -- The magnet is not self shielded as 1.5T and 3T scanners for clinical use are. Due to the high field strength the spread of the magnetic field higher than 5 Gauss would be quite large. Therefore, the scanner is placed in a 440 ton (400 metric ton) six sided steel box that forms the largest part of the MR examination room. The box is made of annealed, high-silicon steel plates, 16 inches thick at the center of the room closest to the magnet, tapering to 8 inches thick at the head and foot ends of the box. This magnetic shield brings down the 5 Gauss lines to a manageable size, about 30 feet by 60 feet. Due to the large forces exerted by the magnet on the box, the magnet must be perfectly centered in the box and the box is constructed to 1/8 inch tolerance. The steel erector was Richard Lee of Shreveport, LA (whom I believe you have already contacted) who is a contractor of Imedco America, Inc. of Noblesville, IN who designed the shield in concert with the magnet manufacturer, Magnex Scientific, Inc.

Vibration -- The Baltimore Metro runs underground in front of this new building - and a station is directly across from the building. Also there is a large amount of vehicle traffic on the 2 streets adjacent to the building. Due to vibrations from these two sources, the entire MR examination room was placed on air springs manufactured by Hammond Kinetics of Dublin, Ohio. These 26 air springs will be inflated when the construction is complete and will lift the examination room, with the 440 ton shield, 35 ton magnet and all interior finishes (1.25 million pounds total) about 1/4 inch off their supports. Optical sensors in three locations sense the position of the room and controllers adjust the pressure in the air springs to keep the room level. This system will completely isolate the MR scanner from outside vibrations.

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