John Rowland Mallard

Human whole-body NMR tomographic imaging: normal sections

Abstract In this paper we demonstrate the kind of images that can be produced by a nuclear magnetic resonance (NMR) tomographic section imager from healthy human subjects. Details of the instrumentation and imaging techniques can be found elsewhere (Hutchison et al., 1980; Edelstein et al., 1980), but a brief description of the imaging method is given here. Our imaging machine is based on a four-coil, air-cored electromagnet manufactured by the Oxford Instrument Company. It produces a magnetic field of 0.04 T and a consequent NMR frequency of 1.7 MHz for the hydrogen protons of body tissues. Our machine uses the NMR signals from hydrogen protons in water and in fat. The machine produces two kinds of image. The first uses proton density as the imaging parameter, and the second uses proton spin-lattice relaxation time (T1). T1 in wet tissues depends essentially on the relative proportions of free and bound water within the tissue under examination; tissues with more free water have longer relaxation times (...

A low field NMR imager for clinical use

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.