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Four 31P NMR spectroscopy parameters were measured non-invasively in the liver of 11 healthy pigs and 9 pigs with CCl4-induced liver disease: (i) absolute molar concentration of phosphorous metabolites; (ii) pH based on the chemical shift of the P(i) peak; (iii) T1 of the peaks in the 31P NMR spectrum; and (iv) changes in ATP, P1 and phosphomonoester after fructose administration. Liver disease was verified by histology and blood chemistry. The concentration of ATP decreased from 3.0(2.8-3.1) to 2.0(2.0-2.4) mM (median and quartiles) when liver disease was induced (p < 0.05). The concentration of phosphodiesters (PDEs) decreased from 14.8(11.4-19.5) to 8.7(7.4-11.6) mM (p < 0.05). pH increased by 0.1 unit. T1 relaxation times for the gamma-, alpha- and beta-ATP peaks increased from 320(249-471) to 577(506-638) ms (p < 0.01), from 765(611-786) to 906(820-1058) ms (p < 0.05) and from 402(327-509) to 579(543-743) ms (p < 0.01), respectively, while T1 for the PDE peak decreased from 2204(1909-2404) to 1758(1502-1894) ms (p < 0.05). In the healthy animals injection of fructose was followed by a reduction of ATP (beta-ATP). In diseased livers this reduction was significantly smaller. In conclusion, it was possible non-invasively to show differences between healthy and diseased livers in all NMR parameters evaluated. This means that 31P NMR spectroscopy may have a potential as a non-invasive diagnostic method for studying liver disease.

The homogeneity of the magnetic field of an Oxford 85/310HR magnet was optimized with the use of passive shims (i.e., pieces of steel) and room-temperature electronic shims. Both the characteristics of the passive shims and the current settings for the room-temperature electronic shims were calculated with the goal of minimizing field inhomogeneities as assessed by Fourier analysis of data from circular field plots. The measurement techniques, the methods of data analysis, and the techniques employed in correcting the magnetic field are presented. Difficulties and constructive approaches are suggested in these descriptions. The final results show a field of excellent homogeneity over a 10-cm-diameter spherical volume, with a peak-to-peak variation of 3.2 ppm, which is better than the manufacturer's expected specification of 5 ppm. A water-filled sphere of 10 cm diameter gave a half-height linewidth of 0.14 ppm after a small amount of additional touch-up shimming. The field homogeneity as corrected is much improved over its original state, allowing the acquisition of improved spectra from samples of a size several centimeters in each linear dimension. Thus the field homogeneity is more useful for in vivo spectroscopy, the purpose for which the magnet was intended.