Deconvolution Analysis of Renograms Obtained with Simultaneously Administered ^99mTc-DTPAand ¹³¹l-Hippuran

Seventy patients were studied with a dual radionuclide technique. The conventional renograms and the blood curve were subjected to deconvolution analysis using the matrix algorithm method, and the following curve data calculated from the retention functions: absolute and relative amplitudes, minimum time of the retention function, maximum time of the retention function and mean transit time. The findings with the two radiopharmaceuticals ^99mTc-DTPA and ¹³¹l-Hippuran were compared under normal and pathological conditions. The correlations between the data with ^99mTc-DTPA and those with ¹³¹l-Hippuran were highly significant (p <0.01). So was the correlation between the absolute amplitude of the retention curve and the rate of uptake based on the corresponding renogram (p <0.01). Due to the difference in the renal handling of the two tracers, longer maximum times were obtained with ^99mTc-DTPA. The mean transit times were also longer with ^99mTc-DTPA, except in kidneys with parenchymal insufficiency. The highest amplitudes were found in normal kidneys, while the lowest values were observed in parenchymal insufficiency. In the group with acute ureteral obstruction, the mean transit times tended to be increased. The maximum times were even more increased. With both tracers it is possible to distinguish between the three groups of renal conditions studied here: Normal, parenchymal insufficiency, and acute ureteral obstruction.

Zusammenfassung

70 Patienten wurden mit einer Doppelradioisotopentechnik untersucht. Die konventionellen Renogramme und die Blutkurve wurden einer Dekonvolutionsanalyse nach dem Matrixalgorithmus unterworfen. Folgende Größen wurden aus der Retentionskurve berechnet: Absolute und relative Amplituden, minimale und maximale Zeit der Retention und die mittlere Transitzeit. Die Ergebnisse mit den zwei Radiopharmazeutika ^99mTc-DTPA und ¹³¹J-Hippuran wurden unter normalen und pathologischen Bedingungen miteinander verglichen. Die Korrelationen zwischen den ^99mTc-DTPA-und den ¹³¹J-Hip-puran-Daten waren hochsignifikant (p <0,01); ebenso die Korrelation zwischen der absoluten Amplitude der Retentionskurve und der Aufnahmerate basierend auf dem entsprechenden Renogramm (p <0,01). Aufgrund der unterschiedlichen renalen Kinetik der zwei Tracer ergaben sich längere Maximalzeiten mit ^99mTc-DTPA. Ebenso waren die mittleren Transitzeiten mit ^99mTc-DTPA länger, ausgenommen in Nieren mit parenchymaler Insuffizienz. Die höchsten Amplituden wurden in normalen Nieren gefunden, während die niedrigen Werte bei parenchymaler Insuffizienz beobachtet wurden. In der Gruppe mit akuter Ureterobstruktion war eine Tendenz zur Verlängerung der mittleren Transitzeiten festzustellen. Die Maximalzeiten waren nochmals verlängert. Mit beiden Tracern war es möglich, zwischen den drei Gruppen renaler Zustände zu unterscheiden, die hier untersucht wurden: Normale, parenchymale Insuffizienz und akute Ureterobstruktion.

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