BIOLOGICAL HALF-LIFE OF AEROSOLIZED TC-99M-DIETHYLENETRIAMINEPENTAACETATE IN VARIOUS LUNG REGIONS OF CLINICALLY NORMAL BEAGLES

The biological half-life (T-B) of aerosolized Tc-99m-diethylenetriamin epentaacetate was determined in 14 lung regions of 18 clinically norma l Beagles. Three groups of lung regions or volumes were identified on the basis of significantly (P < 0.05) different T-B. Group A (mean +/- SD T-B, 82 +/- 21 minutes) included the transversely oriented cranial and caudal nonperihilar regions. Group B (mean +/- SD, 61 +/- 15 minu tes) represented all sagittally oriented lung regions and the entire l ung field. Group C (mean +/- SD, 49 +/- 11 minutes) included the trans versely oriented cranial and caudal perihilar regions. Clearance of Tc -99m-diethylenetriaminepentaacetate is considered a function of transe pithelial transport into the blood, as well as bronchial transport via the mucociliary transport mechanism.