^99mTc DTPA Scanning with Diuretic Washout. Is it Useful in the Investigation of Obstruction in the Presence of Gross Renal Tract Dilatation?

Abstract

Diuretic-enhanced 99mTc DTPA renal scanning aims to determine whether or not a kidney is obstructed. In the presence of gross renal tract dilatation the validity of this technique is questioned. Twenty-eight patients (51 kidneys) with the prune belly syndrome, characterised by gross dilatation and tortuosity of the ureters, were studied. These patients underwent diuretic 99mTc DTPA scanning at the time of diagnosis and at yearly intervals thereafter. Long-term clinical follow-up (3 years) with serial serum creatinine was available in all children. In all cases renal function remained stable and on this basis urinary tract obstruction was excluded. Analysis of the first 99mTc DTPA scan included differential function, whole kidney mean transit time (WKMTT) and the time taken for tracer activity to fall to 75% of peak activity after diuretic stimulus (T75). Using the 99mTc DTPA scan, obstruction can be excluded if the WKMTT is less than 5 min or, in the presence of a prolonged WKMTT, if the diuretic stimulus results in a T75 of less than 5 min. A T75 of between 5 and 10 min is considered equivocal and a T75 exceeding 10 min means that obstruction cannot be excluded. 99mTc DTPA scanning, using these criteria for diagnosis, provided false positive information in 22 kidneys (43%). There were no false negatives. 99mTc DTPA scanning with diuretic washout, using WKMTT and T75 criteria, is not appropriate for the detection of renal tract obstruction in the presence of marked upper renal tract dilatation, since the false positive rate of 43% is unacceptably high.

Fast simultaneous assessment of renal and liver function using polymethine dyes in animal models of chronic and acute organ injury

“…Estimation of glomerular filtration rate via inulin-clearance measurement represents today’s gold standard to assess kidney function but this requires time consuming urine sampling and fails to assess rapid changes in organ function prototypical for the intensive care unit. Other techniques such as technetium-99m diethylene triamine penta-acetic acid clearance are also used to evaluate kidney function with respect to filtration 28 – 30 . However, these methods are time-consuming to conduct and therefore very seldom used in intensive care units.…”

Kombinierte statisch-dynamische MR-Urographie zur morphologisch-funktionellen Diagnostik angeborener Harntransportstörungen

“…Da unsere experimentellen Studien die Überlegenheit der MRU gegenüber der AUG nachgewiesen hatten [38,39] [47], während 99m Tc-MAG3 vorwiegend durch tubuläre Sekretion ausgeschieden wird [48]. Aufgrund der geringeren Extraktionsfraktion von DTPA im Vergleich zu MAG3 [5] wird der Harnabfluss bei massiver Dilatation fälschlich zu schlecht eingeschätzt [6,49]. Die Nierenfunktion scheint durch diesen Unterschied nicht beeinflusst zu werden, was zum einen durch unsere Ergebnisse belegt wird und wofür sich zum anderen auch in der Literatur Hinweise finden lassen [5,6].…”

International Scientific Committee of Radionuclides in Nephrourology (ISCORN) Consensus on Renal Transit Time Measurements

“…35 One problem of parenchymal transit times in that, in practice, in a renal scan, there is not clear distinction between pure parenchyma and cavities, so determining this transit time is a technical challenge, especially for small children and when parenchyma is thinned by dilated cavities. 74 Whole kidney transit time. Normal MWKTT for DTPA is somewhat longer than parenchymal TT (usually in the range 2-4 minutes), depending on studies, age and hydration state ( Fig.…”

“…In a small series, MWKTT paradoxically increased in as many cases as it decreased after pyeloplasty 195 in pediatric patients with highly dilated systems, but without obstruction on simple followup, 43% were false-positive using MWKTT with DTPA and a threshold of 5 minutes. 74 Diuresis renography was unable to predict which children would undergo surgery in a prospective trial of conservative management. 168,169,171 An extensive metananalysis review of the literature was published in 2002, 196 concluding that among the 474 children for whom it was decided to follow up without surgery, 10% crossed over to surgery (mostly for decrease in function or increase in pelvic volume) and only 3 kidneys (0.6%) significantly lost function.…”