A low field NMR imager for clinical use

Abstract

The essential design features of a vertical field 0.08 T, 3.4 MHz NMR proton imager are described. The machine was constructed in-house following successful clinical trials with a prototype 1.7 MHz imager. Based on a four-coil air-cored resistive electromagnet, the machine acquires single-slice 128*128 pixel images in about 4 min using an interleaved saturation recovery, inversion recovery sequence, where spin echoes are formed by gradient reversal. The image formation technique is spin warp. Since its installation in the Aberdeen Royal Infirmary in early 1983, over 4000 patients have have scanned. Images are presented to illustrate its performance.