LOCALIZED P-31 MR SPECTROSCOPY OF THE TRANSPLANTED HUMAN KIDNEY IN-SITU SHOWS ALTERED METABOLISM REJECTION AND ACUTE TUBULAR-NECROSIS

The purpose of this study was to investigate the function of transplan t kidneys in situ, and to detect pathologic changes, using volume-sele ctive phosphorous NMR spectroscopy (P-31 MRS). Localized P-31 MR spect ra were obtained from 37 patients using a whole-body MR scanner with a combination of surface coils, adiabatic excitation pulses, and a modi fied image-selected in vivo spectroscopy (ISIS) sequence. Seventeen pa tients with pathologic changes after renal transplant were compared wi th a control group of 20 patients with no evidence of transplant dysfu nction. The transplant kidneys with rejection reaction showed higher r atios of inorganic phosphate (P-i) to adenosine triphosphate-alpha (AT P-alpha) than the normal control group (.4 +/- .16 compared with .22 /- .11, P = .01) and reduced pH. The spectra of transplant kidneys wit h tubular necrosis had lower phosphomonoester (PME)/phosphodiester (PD E) ratios than the control group (.65 +/- .35 compared with .96 +/- .5 , P = .04), The pathologies of rejection and tubular necrosis could be differentiated from each other by pH (6.93 +/- .1 in rejection versus 7.14 +/- .19 in tubular necrosis, P = .04), Preliminary results indic ate that localized image-guided P-31 MR spectroscopy of transplant kid neys in situ can detect rejection reactions and acute tubular necrosis noninvasively, providing an incentive for further research.