7T PROTON RESONANT FREQUENCY SHIFT & R2* IN FROZEN EXVIVO RENAL TISSUE

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This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. ntroduction Image-guided cryoablation is a minimally invasive therapy for renal cancer. To this end, MR parameters of frozen tissue have been measured with ultrashort TE MR imaging on a low field interventional system [1,2], but understanding of the contribution of the proton resonant frequency shift to the observed phase changes have been limited by the SNR of the frozen tissue at low field. Aims The purpose of this study was to measure the MR parameters of frozen tissue (PRF shift and R2*) on a high field spectrometer. Methods Freshly excised kidney samples were imaged with the Varian INOVA 300 MHz NMR system. Tissue temperature was decreased to 30¿C in steps. To calculate 1H frequency shift with temperature, the baseline frequency was subtracted from the 1H frequency at every temperature. The R2* was calculated from the linewidth.