High-Field 31P Magnetic Resonance Studies for Evaluating Kidney Viability

The application of 31P magnetic resonance (MR) to provide a noninvasive evaluation of renal phosphorus metabolism is well established [7, 13, 14]. In a variety of 31P MR studies of excised or perfused kidneys initial attention has been given to determining the time course of nucleotide (NTP + NDP) depletion (sum of all nucleoside 5’-tri- and diphosphates, primarily ATP and ADP) and intrarenal acidosis during cold and warm ischemia [9]. Within a few minutes depletion of intrarenal NTP was noted, and a rapid onset of acidosis was observed. Previous investigations using low-field 31P MR of the isolated perfused kidney demonstrated sequential changes in phosphate components during ischemia [9]. However, the information provided about the components of different signal groups was insufficient; the renal 31P MR spectra obtained at field strengths lower than 4.7 T did not allow adequate sensitivity and resolution for many of the individual phosphate metabolites, for example, detection of phosphocreatine (PCr), separation of NTP and NDP, resolution of phosphomonoesters (PME) into phosphocholine (PC) and phosphoethanolamine (PE) and of diesters (PDE) into glycerophosphocholine (GPC) and glycerophosphoethanolamine (GPE). Through the use of very high field strengths (>7 T) these problems can be solved, at least for ex vivo studies.