Advances in Diuretic Renography Today: A Clinical Update

Diuretic renography was proposed in the late 1970s to distinguish between dilated, obstructed, and non-obstructed urinary tracts by measuring the Diuresis Excretion Index with a gamma camera. The test was originally performed with the patient seated and a dose of furosemide (0.50 mg/kg) administered 20 min after tracer injection (F+20 method), with the examination lasting for 15–20 min. However, many nuclear physicians opted for a supine, prone, or semi-recumbent position to reduce movement and avoid side effects such as diuretic-induced hypotension. Several methods (F-15, Well-Tempered F+20, F0, F+2, etc) have been proposed using varying furosemide dosages (0.5– 1 mg/kg) and diuretic administration times. Unfortunately, the supine position produces radiotracer stasis even when there is no obstruction, resulting in an inaccurate output index. Furthermore, high furosemide doses cause bladder fullness issues. The lack of technical standardization leads to ambiguous and incomparable results. The F+10 [seated position (sp)] method is a novel approach that assesses patients in a sitting position with shorter intervals and a lower dose of furosemide (0.25 mg/kg), resulting in improved compliance. It also enables accurate calculation of outflow data, such as the 20 min/peak ratio, which is favored by the gravity effect.