Complete and partial ureteral obstruction: evaluation of renal effects with P-31 MR spectroscopy and Tc-DMSA scintigraphy

Phosphorus-31 magnetic resonance (MR) spectroscopy was used to study the effects of partial and complete ureteral obstruction on the porcine kidney; results were compared with renal tubular function as determined with technetium-99m dimercaptosuccinic acid (DMSA) scintigraphy. Twenty-seven pigs were used: nine as sham-operated controls, six with partial ureteral obstruction, and 12 with complete ureteral obstruction. P-31 MR spectra and Tc-DMSA scintiscans were obtained weekly over 3 weeks. Partial obstruction caused no significant change in P-31 MR spectra, whereas Tc-DMSA scintiscans showed a 74% decrease in tubular function by the end of 3 weeks. Complete obstruction caused a 43% reduction in the mean adenosine triphosphate (ATP) to inorganic phosphate (Pi) ratio, which paralleled the 96% decrease in Tc-DMSA uptake over 3 weeks. The difference in ATP/Pi ratios between control and completely obstructed kidneys was significant (P less than .01) at 2 and 3 weeks after ligation. These results indicate that radionuclide Tc-99m DMSA uptake is very sensitive to the pathophysiologic changes in renal tubular function, while the organ average cellular bioenergetic state (ATP/Pi) is not as strongly affected.