CANM Guidelines for V/P SPECT in PE

"The best widely available agent for ventilation is 99mTc-Technegas, an aerosol of carbon nanoparticles (5-200 nm) generated in a high temperature furnace (Technegas Generator, Cyclomedica). Because of the very small particle size, this agent is distributed in the lungs almost like a gas and deposited in alveoli by diffusion, where they remain stable, thus providing the best possible images for ventilation SPECT."