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PAEDIATRIC UROLOGY

5.2.3 Diuresis renography

Because of its low radiation exposure, Tc99m-MAG3 is the radionuclide of choice in diuresis renography. The examination is carried out after standardized hydration with a transurethral catheter in place. Renal arterial perfusion, intrarenal cortical transit and excretion of the tracer into the collecting system are measured. If excretion is impaired, it takes longer for half the maximum activity of the radio-isotope to reach the renal pelvis (T1/2) after application of furosemide. With rapid absorption of the tracer and prompt washing out effect on diuresis (T1/2 < 10 min), obstruction is unlikely. Impaired or deteriorating split renal function in newborns or young infants with upper tract dilatation may be the best indicator of significant obstruction.