[Characteristics of radiopharmaceutical delivered from 99mTc-DTPA in the technegas generator].
99mTc-DTPA aerosol permeates the alveolar membrane by an intercellular pathway. Measurement of the clearance rate of 99mTc-DTPA aerosol is useful for assessing injury of the lung epithelium. Pertechnegas (P-gas) is also used to assess epithelial permeability, but its clearance is too rapid to evaluate lung epithelial permeability. The aims of this study were first to generate 99mTc-DTPA fine aerosol (D-gas), second to characterize D-gas by radiochromatography and an in vivo study in the rat, and third to investigate the clinical significance of D-gas in comparison with 99mTc-DTPA aerosol and P-gas. We generated D-gas in a chamber with an atmosphere of 3% oxygen and 97% argon inside the Technegas Generator. The clearance half-time of D-gas was 19.8 +/- 4.0 min in eight normal non-smoker subjects, 12.0 +/- 2.8 min in four smoker subjects, and 31 +/- 11.2 min in three with idiopathic interstitial pneumonia (IIP). In radiochromatography, the development of D-gas was the same as that of P-gas and different from that of 99mTc-DTPA solution. In the in vivo study using a rat, the distribution of intravenously injected D-gas solution was the same as that of 99mTcO4-, but different from that of 99mTc-DTPA solution. These results suggest that 99mTc-DTPA separates to free 99mTcO4- in the chamber of the Technegas Generator and that D-gas behaves in the same manner as P-gas. In conclusion, D-gas has no clinical significance for the assessment of epithelial permeability.
Dohi
M
M
Department of Radiology, Jikei University, School of Medicine.
Moriya
E
E
Mori
Y
Y
Kawakami
K
K
Yoshizawa
Y
Y
D000336:Aerosols; D000818:Animals; D002463:Cell Membrane Permeability; D004848:Epithelium / Q000378:metabolism; D006207:Half-Life; D006801:Humans; D008171:Lung Diseases / Q000000981:diagnostic imaging; D011650:Pulmonary Alveoli / Q000378:metabolism; D011877:Radionuclide Imaging; D051381:Rats; D017208:Rats, Wistar; D013670:Sodium Pertechnetate Tc 99m / Q000493:pharmacokinetics; D016284:Technetium Tc 99m Pentetate / Q000493:pharmacokinetics*
D000336:Aerosols; C056708:Technegas; D013670:Sodium Pertechnetate Tc 99m; D016284:Technetium Tc 99m Pentetate