ASSESSMENT OF INSITU RENAL-TRANSPLANT VIABILITY BY P-31-MRS - EXPERIMENTAL-STUDY IN CANINES

In 14 in situ canine renal transplants, intracellular phosphorus metab olites were evaluated by phosphorus-31 magnetic resonance spectroscopy (P-31-MRS), performed using surface coils to investigate the usefulne ss of this technique for assessing renal viability in situ. Group I co ntrol kidneys (n = 5) were autografts, as were Group II (n = 5) kidney s: the latter group were subjected to surgically induced vascular isch emia and thrombosis. Group III kidneys (n = 4) were rejecting allograf ts. Renal flow and function, as measured by Tc-99m-DTPA, and findings on histologic examination were correlated with P-31-MRS spectra. Group I kidneys showed excellent viability on both Tc-99m-DTPA studies and biopsy evaluation, and their P-31-MRS-derived ratios of phosphomonoest ers/inorganic phosphate (PME/P(i)) and adenosine triphosphate/P(i) (AT P/P(i)) were high (1.32 +/- 0.23 and 0.90 +/- 0.36, respectively). In contrast, Group II kidneys demonstrated poor flow and function, histol ogic evidence of severe ischemia from venous and arterial thrombosis, and significantly (P < 0.005) less viability than controls, as monitor ed by P-31-MRS PME/P(i) (0.58 +/- 0.30) and ATP/P(i) (0.20 +/- 0.13) r atios. Group III kidneys also demonstrated poor flow and function with Tc-99m-DTPA, and the associated histologically injury was noted to be caused by accelerated rejection and severe vascular damage. PME/P(i) (0.24 +/- 0.22) and ATP/P(i) (0.10 +/- 0.01) ratios were also signific antly (P < 0.005) less than those in controls, reflecting nonviability . The P-31-MRS-derived PME/P(i) and ATP/P(i) ratios enable a qualitati ve noninvasive assessment of blood flow-dependent renal viability, but with currently used localization techniques the differentiation betwe en severe ischemia and severe acute rejection was not possible.