The choice of timing for diuresis renography: the F + 0 method

To investigate a method of diuresis renography where the radiopharmaceutical and frusemide (diuretic) are given simultaneously, in contrast to conventional renography which involves an intravenous injection with frusemide 20 min after administering the radiopharmaceutical (F + 20) or 15 min before (F - 15), with particular interest in the effect of this change on assessing split renal function and interpreting upper tract drainage dynamics.

In a prospective study, 29 patients (18 women and 11 men, mean age 47 years, range 21--86) were assessed. Each patient had two renograms taken over a 48-h period, either by the F + 20 or F - 15, and the F + 0 method: Data for split renal function and drainage curves were obtained in the usual way. Two independent assessments of the drainage curves were obtained and the results compared.

The split function assessments were identical (< 5% variation) in all but two patients; 26 of 29 (90%) gave identical conclusions about the drainage curves. The three patients with discrepancies between the studies had either hugely dilated upper tracts or otherwise had multiple complicating factors, e.g. impaired renal function, neuropathic bladder.

F + 0 renography has been used in paediatric urological practice before, but there are no comparative studies and no data on its use in adults. This prospective study confirmed that in investigating dilated upper tracts, the F + 0 technique gives similar results to the conventional techniques. The F + 0 method has the potential to reduce the time required to undertake standard F + 20 renography but it may not be useful in evaluating the grossly dilated upper tract, where the F-15 technique has the best record in terms of reducing equivocal results.