Radionuclide Cystography: The Significance of Retention Time of the Refluxed Radioisotope

Publisher Website
Google Scholar
Abstract
Patients (36) with vesicoureteral reflux were studied in 45 renal units by isotope cystography and a dynamic renal function scan performed 24-48 h after the cystography. Functional impairment was found in 21 renal units. To evaluate the significance of the time between voiding and complete disappearance of the radioisotope that refluxed from the kidney (retention time), the presence of the labeled particles in the kidney was followed continuously and intermittently during a prolonged interval. There was a significant difference between the retention time found in the impaired kidneys and that in the normally functioning kidneys. In 91.7% of the normally functioning kidneys retention time was < 5 min, whereas in 86% of the impaired kidneys it was > 10 min and in 56% it was > 20 min. No significant correlation was found between the retention time and intrarenal reflux or dilatation of the collecting system (patients classified as having radiological grades III and IV reflux were not included in the study). A retention time > 10 min may be correlated with decreased renal function. The retention of Tc sulfur colloid particles may be analogous to the retention of similar size bacteria and suggests a possible pathophysiologic explanation for the development of renal dysfunction owing to the prolonged presence of bacteria in the kidney after reflux.