Self-shielded 4.0-T superferric MR magnet

A 4.5-T 30-cm room temperature bore superferric magnet has been demonstrated to produce useful images and spectra. The magnet has a fringe field of less than 1 m and a homogeneous volume of 10-cm diameter at the 10-ppm level. Good images were obtained of various fruit and a cat's head. Two-dimensional chemical shift images were obtained with better than 0.5-ppm resolution in the chemical shift axis. Proton and phosphorus spectra were obtained from a phantom with 0.1-ppm line widths at half height. In vivo phosphorus spectra were obtained from rabbit muscle with line width of better than 0.5 ppm. All data were collected with a 15,000-amp power supply located 2 m off axis and a 80-L/h operating helium liquifier 6 m on axis. These demonstrate that self-shielded superferric magnets produce results comparable to those of conventional superconducting magnets but without siting limitations