A versatile multinuclear probe designed for in vivo NMR spectroscopy: Applications to subcutaneous human tumors in mice

We describe a versatile NMR probe that is designed for a variety of in vivo spectroscopic studies on small animals in vertical wide‐bore magnets. Replaceable brackets enable the coils to be exchanged readily in order to observe ¹H, ¹³C, ³¹P, and other nuclei, and to carry out double‐resonance experiments. Two solenoidal coil designs are described and applied to observe ³¹P, ¹³C, and ¹H natural abundance spectra of subcutaneously implanted human tumors in mice. For ³¹P and ³¹C observation with ¹H decoupling, a concentric coil arrangement was employed with a broadband inner coil and the outer coil tuned to ¹H at 400 MHz. A single coil tuned to 400 MHz was used to observe ¹H resonances. A thin copper foil design was found to be superior with respect to S/N and resolution to previously described Faraday shields used to shield the NMR signals originating from nontumor tissues. ³¹P spectra of in vivo tumor tissue were compared to spectra of in vitro perfused tumor cells of the same origin. Tumor tissue in vivo exhibited much higher levels of inorganic phosphate and phosphocreatine. Signals from [¹³C₂]glucose and its major metabolite, [¹³C₂]lactate, were readily observed and monitored in an unobstructed region of the ¹³C spectra of tumor tissue in vivo following the injection of [¹³C₂]glucose in adjacent tissues. A ¹H spectrum of tumor tissue, characterized by five broad resonances, was observed with excellent water suppression. © 1988 Academic Press, Inc.