In the development of radio frequency (RF) coils for better quality of the mini-type permanent magnetic resonance imager for using in the small animal imaging, the solenoid RF coil has a special advantage for permanent magnetic system based on analyses of various types.of RF coils. However, it is not satisfied for imaging if the RF coils are directly used. By theoretical analyses of the magnetic field properties produced from the solenoid coil, the research direction was determined by careful studies to raise further the uniformity of the magnetic field coil, receiving coil sensitivity for signals and signal-to-noise ratio (SNR). The method had certain advantages and avoided some shortcomings of the other different coil types, such as, birdcage coil, saddle shaped coil and phased array coil by using the alloy materials (from our own patent). The RF coils were designed, developed and made for keeled applicable to permanent magnet-type magnetic resonance imager, multi-coil combination-type, single-channel overall RF receiving coil, and applied for a patent. Mounted on three instruments (25 mm aperture, with main magnetic field strength of 0.5 T or 1.5 T, and 50 mm aperture, with main magnetic field strength of 0.48 T), we performed experiments with mice, rats, and nude mice bearing tumors. The experimental results indicated that the RF receiving coil was fully applicable to the permanent magnet-type imaging system.
Animals ; Magnetic Fields ; Magnetic Resonance Imaging ; instrumentation ; Magnets ; Mice ; Mice, Nude ; Phantoms, Imaging ; Radio Waves ; Rats

We developed a three-dimensional mini-type permanent magnetic resonance imaging (MRI) device in our lab. The purposes of this study were (1) for further development of MRI technologies, (2) for support of broadening practices of animal test modeling in medical research, and (3) for training more specialists from colleges or universities in the field of MRI. This paper describes the research and development at our lab(s), especially stressing on the design of the main magnet, the gradient coil and the radio frequency coil. In addition, the specific methodologies used in our lab(s) and the related data are emphasized. The 3D MRI technologies have met the needs of using small animals, super thin sections of live animal body and high imaging resolutions. MRI images of mice head and abdominal have been obtained successfully by using the imager that we developed. The imaging results and analyses have also been discussed.
Animals ; Equipment Design ; Imaging, Three-Dimensional ; instrumentation ; Magnetic Resonance Imaging ; instrumentation ; methods ; Mice