Bulk magnetic susceptibility shifts in nmr studies of compartmentalized samples: use of paramagnetic reagents

Ksimon ‐.C. Chu, Yan Xu, James A. Balschi, Charles S. Springer

Research output: Contribution to journalArticle

310 Scopus citations

Abstract

The bulk magnetic susceptibility (BMS) shift of a nuclear resonance frequency caused by a paramagnetic compound is of importance in in vivo NMR, both magnetic resonance spectroscopy and magnetic resonance imaging. However, since it is a rather complicated phenomenon, it has been the source of many misinterpretations in the literature. We have reworked and organized the theory of the BMS shift. This includes accounting for the important effects of local susceptibility. We have conducted experiments on phantom samples in order to illustrate the principles involved. Our phantoms consist of capillaries and coaxial cylinders. They simulate the situations of blood vessels oriented parallel and perpendicular to the magnetic field and the interstitial spaces surrounding them. In most of our experiments, the paramagnetic compound was one of several different hyperfine shift reagents for cation resonances. These were chosen to cover a range of potencies, in both magnitude and sign, of the shifts they produce. However, we also used a reagent which was incapable of inducing a hyperfine shift and thus could cause only a BMS shift. Although we report only 23Na spectra in this paper, the latter samples simulate the cases where one observes the water 1H resonance in experiments employing hyperfine shift reagents for cations. There have been a number of such investigations recently reported in the literature. The principles considered in this paper allow us to offer new interpretations for the results of several experiments published in the last few years.

Original languageEnglish (US)
Pages (from-to)239-262
Number of pages24
JournalMagnetic Resonance in Medicine
Volume13
Issue number2
DOIs
StatePublished - Feb 1990

ASJC Scopus subject areas

  • Radiology Nuclear Medicine and imaging

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