Renal transit time of Tc-99m-diethylenetriaminepentacetic acid (DTPA) in normal dogs

The transit time of Tc-99m-DTPA in the kidneys is an indicator of renal fun ction that has been used in humans for the diagnosis of renal obstruction, renal artery stenosis, and rejection of renal transplants. Its use, however , has not been reported in the dog. Tc-99m-DTPA scintigraphy was performed in 8 normal dogs and the time of peak was calculated as the time between th e injection and the maximum renal uptake. Deconvolution analysis was perfor med to estimate the renal retention function using 3 different techniques, i,e, the matrix method, the fast Fourier transform (FFT) method, and the co nstrained least square method. The parenchymal and whole kidney mean transi t times were calculated from the deconvolved renogram using alternatively t he thorax and the aorta as the input function. Average mean transit times r anged from 137 to 184 seconds. Parenchymal mean transit time was significan tly shorter than whole kidney mean transit time (P < 0,03), Mean transit ti me calculated with the thorax as the input function was significantly longe r than mean transit time calculated with the aorta (P < 0,001), No differen ces were observed between mean transit time calculated with the matrix, FFT and constrained least square methods.