AN EXTERNAL REFERENCE FOR IN-VIVO QUANTIFICATION OF H-1 SPECTROSCOPY

We studied the validity of using an external signal reference for abso lute quantification of brain metabolites, We chose cyclohexane as the signal standard; An expression of a perturbed magnetic field in diamag netic cylindrical materials was first obtained by using a method of eq uivalent magnetic charges. Broadening of the spectrum in this perturbe d magnetic field was then computed, We performed phantom studies. We m easured the full width at half maximum (FWHM) of the cyclohexane and t he signal ratio (SR) between water and cyclohexane in spheres of two d ifferent diameters, and in cylinders of various diameters and lengths. The observed FWHM and SR in the small cylinders had large variations in distribution, whereas those in the spheres and in the large cylinde rs had small variations, Specifically, in a cylinder with a diameter > 5 cm and with a length >10 cm, the variation of the SR was <1.0%. The diameter and the length of the cylinder preferably are large when a cy lindrical material is adopted as an external signal standard. Copyrigh t (C) 1996 Elsevier Science Inc.