Evaluation of renal function and morphology in children by 99mTc-DTPA gamma camera renography

The purpose of the present investigation was to evaluate the use of 99mTc-DTPA (diethylenetriaminepenta-acetate) gamma camera renography for the study of kidney function as well as morphology. Sixty-nine children with urinary tract infection or congenital hydronephrosis aged 6 days to 13.6 years were studied. A method for determination of the glomerular filtration rate (GFR) from the recorded curves without use of blood or urine samples was tested in 65 consecutive children. From each renogram an uptake index was determined. After a weight/height correction the sum of right and left kidney uptake index correlated with total GFR determined from plasma clearance of 51Cr-EDTA (ethylenediaminetetra-acetate) measured on the same day (r = 0.96). The relative standard error of estimating GFR from the renograms was 10.7% at GFR = 100 ml/min and 14.6% at GFR = 50 ml/min. In a subgroup including 20 children no difference was found in kidney morphology and length studied by renography and intravenous urography, the latter providing more details concerning the urinary tract. Relative kidney length did not correlate with relative renal function determined by renography, emphasizing the difficulty in determination of relative renal function by urography. In conclusion, not only relative but also absolute renal function (GFR) can be determined in children by 99mTc-DTPA renography; at the same time kidney and urinary tract morphology are evaluated. In our hands, 99mTc-DTPA renography has become a useful diagnostic tool, lowering the need for the more cumbersome intravenous urography and 51Cr-EDTA plasma clearance. However, intravenous urography is mandatory for the detailed study of the urinary tract, and use of the 51Cr-EDTA plasma clearance technique is necessary when a very reliable determination of GFR is wanted.