Technetium-99m diethylenetriaminepentaacetic acid radioaerosol scintigraphy in organophosphate induced pulmonary toxicity: experimental study.

The aim of this experimental study was to investigate pathological signs of lung damages caused by acute organophosphate (OP) poisoning by using Tc-99m DTPA radioaerosol scintigraphy and histopathological investigation. Fourteen rabbits were divided into two equal groups (n = 7). Group 1 (control group) received normal saline (same volume of fenthion, 2 ml/kg) via orogastric tube. Group 2 (OP toxicity group) received 150 mg/kg of fenthion (diluted fenthion, 2 ml/kg) via orogastric tube. Six hours later, Tc-99m-DTPA aerosol inhalation lung scintigraphy was performed in both groups. Then all rabbits were anesthetized with ketamine hydrochloride (35 mg/kg, i.p.) and xysilazine (5 mg/kg, i.p.), and sacrificed by intracardiac blood discharge. The lungs were then removed. There was a significant difference in T1/2 values of Tc-99m DTPA clearance between control group and OP toxicity group (p = 0.04). Intraparenchymal vascular congestion and thrombosis, intraparenchymal hemorrhage, respiratory epithelial proliferation, number of macrophages in the alveolar, and bronchial lumen, alveolar destruction, emphysematous changes, and bronchoalveolar hemorrhage scores were significantly higher in the rabbits exposed to OP compared with the control group (p < 0.05). This study showed that OP toxicity caused a decrease in the alveolar clearance. Tc-99m DTPA radioaerosol inhalation lung scintigraphy was found to be a sensitive determination of acute lung damage in OP poisoning.