Chemical breakdown of technetium-99m DTPA during nebulization.
Aerosols of 99mTc diethylenetriaminepentaacetic acid ([99mTc]DTPA) used for measuring lung permeability and lung ventilation require a radioaerosol delivery system to produce an aerosol with reproducible size and radiochemical purity. To test how well nebulizers meet this requirement, radiochemical purity of aerosols produced with a jet and an ultrasonic nebulizer was evaluated. The activity median aerodynamic diameter (AMAD) and geometric standard deviation (sigma g) of radioaerosols were 0.46 micron (sigma g = 1.6) for the jet nebulizer and 0.70 micron (sigma g = 1.7) for the ultrasonic nebulizer. Paper and liquid chromatographic assays were obtained on the [99mTc]DTPA aerosol solute produced with each nebulizer. The results of these tests showed major differences in radiochemical purity. Aerosols produced in the jet nebulizer consistently showed greater than 90% of the radioactivity bound to the DTPA ligand whereas aerosols produced in the ultrasonic nebulizer showed less than 10% of the radioactivity bound to DTPA. The results support the need to test radiochemical purity of aerosols before using an aerosol nebulizer for pulmonary imaging and clearance studies.
D000336:Aerosols; D000818:Animals; D002853:Chromatography, Liquid; D002854:Chromatography, Paper; D004285:Dogs; D004355:Drug Stability; D005069:Evaluation Studies as Topic; D005260:Female; D008168:Lung / Q000000981:diagnostic imaging; D009330:Nebulizers and Vaporizers; D004369:Pentetic Acid / Q000032:analysis / Q000378:metabolism*; D011854:Radiochemistry; D011877:Radionuclide Imaging; D013667:Technetium / Q000032:analysis / Q000378:metabolism*; D016284:Technetium Tc 99m Pentetate
D000336:Aerosols; D013667:Technetium; D004369:Pentetic Acid; D016284:Technetium Tc 99m Pentetate