Evaluation of Ventilation Homogeneity as a Marker of Small Airway Disease in Active Smokers

"Technegas-Tc99m is approved by Health Canada for the evaluation of ventilation. Technegas will be prepared with a Technegas Generator (Cyclomedica) according to the manufacturer recommendations with a simmer phase and a burning phase. 95% ethanol will be used to wet the carbon crucible. The crucible will be loaded with 20-30 mCi of Tc99m. Tc99m has a physical half-life of 6 hours.~Technegas will be administered to the patient within 10 minutes of its preparation, in a separate room than the scanning room. The inhalation technique will be rehearsed with the patient prior to the actual inhalation. The patient will be in supine position. A mouth piece and a nose clip will be used. The patient will be instructed to take 3 breaths of Technegas, starting after normal exhalation. A survey meter will be used to monitor the quality of the inhalation."