Effect of hydration and dehydration on technetium-99m CO2 DADS renal studies in normal volunteers.

Ten normal volunteers were studied in the hydrated and dehydrated states with the new renal radiopharmaceutical technetium-99m N,N'-bis(mercapto acetyl)-2, 3-diaminopropanoate [( 99mTc]CO2 DADS). The data were used to determine the effect of hydration and dehydration and to determine the normal range in each state. Visual evaluation of the images indicated that the first appearance of tracer in the collecting system was approximately the same in either state, that the concentration of tracer in the collecting system was always higher in the dehydrated state (p less than 0.01), and that the ureters always appeared more segmented in the dehydrated state (p less than 0.01). Quantitative analysis of the images indicated that the kidney to background ratio 1-2 min after injection was somewhat greater in the dehydrated state (13.5 +/- 4.0) than in the hydrated state (9.8 +/- 2.2) (p less than 0.05), that the size of the bladder was always greater in the hydrated state (p less than 0.05), and there was no difference in the amount of tracer in the bladder at 30 min after injection. The results define the normal hydrated and dehydrated [99mTc]CO2 DADS renal study and identify several differences between the two states which can be explained primarily by differences in urine flow rates.