Development of a Temperature Variable MRI System using a 1.0 Tesla Yokeless Permanent Magnet

Yasuhiko Terada¹, Katsumi Kose¹, Tomoyuki Haishi²

A temperature variable MRI system was developed using a 1.0 Tesla yokeless permanent magnet. The magnetic field inhomogeneity was evaluated to achieve MR imaging over a wide temperature range (-5 to +45 C). The RMS inhomogeneity in the central 15 mm square cubic area increased from 5 to 18 ppm from 35 to -5 C with decreasing temperature. This inhomogeneity variation was mainly caused by z² and x² terms except the first order inhomogeneity. A plant specimen was imaged at -5 and 5 C to demonstrate the usefulness of the system. The free water signal visualized at 5 C disappeared at -5 C while the structured water signal was still visible at -5 C.