Diuretic renal scintigraphy in normal cats.

The purpose of this study was to develop a protocol for diuretic renal scintigraphy (renography) in cats and describe normal findings. 99mTc-DTPA renal scintigraphy was performed twice in 10 healthy cats. Furosemide or saline were injected 4.5 min after radiopharmaceutical administration for the diuretic or control scan, respectively. A dynamic acquisition was performed for 8 min. The following parameters were evaluated: (1) global and individual glomerular filtration rate (GFR); (2) shape of the time-activity curve (TAC); (3) time of peak (TOP); (4) individual kidney excretion half-time (T1/2) of the radiopharmaceutical; (5) percentage of maximum activity measured at the end of the study. Global GFR in the control studies (2.79 +/- 0.83 ml/min/kg, mean +/- SD) did not differ significantly from the diuretic scans (2.34 +/- 0.51 ml/min/kg). The shape of most (16/ 20) TAC of diuretic renograms was similar to those of control renograms. The TOP of the diuretic renogram curves was 3.06 +/- 0.58 min, and did not differ from that of the control scans (3.01 +/- 0.61 min). T1/2 of the diuretic renograms was significantly shorter (5.15 +/- 0.83 min) than that of the control renograms (6.31 +/- 1.50 min). A significantly lower percentage of maximum activity was present at the end of the study in diuretic renograms (median: 47.25%; range: 33.60-59.60%) compared with control renograms (63.40%; 30.00-69.40%). Diuretic renal scintigraphy is a noninvasive and fast procedure to perform in cats. The applicability of this technique needs to be investigated in patients with significantly impaired renal function and obstructive uropathies.