[Evaluation of lung scintigraphy using N-isopropyl-p-[123I]-iodoamphetamine].

N-isopropyl-p-[123I]-iodoamphetamine (123I-IMP) was examined for its relevancy as a labeling medium of lung scintigraphy in 30 patients with lung diseases and 20 healthy subjects. Lung diseases were classified into carcinoma and diffuse lung disease, and the all subjects with normal lung were classified into smokers and nonsmokers. To assess the reduction curve of 123I-IMP, mean transit time was calculated. Forced spirography was performed and spirographic values were analyzed. Spirographic parameters examined were vital capacity percent (%VC), forced expiratory volume in 1 sec divided by forced vital capacity (%) (FEV1.0%), and blood gas data. In the correlation matrix, the mean transit time was correlated with blood gas data, and not with %VC or FEV1.0%. In patients with lung diseases, the mean transit time was significantly prolonged; however, the difference was not significant between groups of carcinoma and benign disease, and between groups of smokers and nonsmokers. Wash-out images were obtained by the subtraction technique using the first frame image and 100-min delayed image. In patients with lung carcinoma, 87.5% of the tumors were depicted on wash-out images. The lesions were also depicted well in benign lung diseases. But among findings of wash-out image by 123I-IMP, air trapping image by 133Xe study and XCT study, there are some discordances to be clarified.