Magnetization transfer attenuates metabolite signals in tumorous and contralateral animal brain: In vivo observations by proton NMR spectroscopy

Tumorous and contralateral rat brain was examined by in vivo single voxel proton NMR spectroscopy. Magnetization transfer (MT) experiments cause attenuation of various metabolite signals. Selective saturation of immobile metabolites was achieved by pulsed RF preirradiation. The method is compared with continuous wave MT generation. In contralateral tissue, MT attenuation is detected for both the CH₃ and the CH₂ protons of (phospho-)creatine (Cr + PCr) and for a signal at 3.44 ppm ascribed to taurine. Significant attenuation is also observed for a signal at 3.78 ppm that is commonly ascribed to the αCH proton of glutamate and glutamine (Glx); however, no effect is observed for the γCH₂ protons of Glx. Within implanted F98 glioma tumors, only the CH₃ signal of Cr + PCr shows significant MT attenuation. Although the MT effect detected for lactate in the tumors fails to reach significance, a significant effect is observed for the lactate signal acquired during 3 to 9 min postmortem.