Reagents for medical use; reactants in the nature of gases and gas mixtures for medical imaging use for medical diagnosis; medical diagnostic reagents and assays for testing of body organs and tissues; medical diagnostic reagents and assays for testing of lung ventilation; medical diagnostic reagents and assays for testing of pulmonary ventilation by positron emission tomography (PET); radiological contrast substances for medical purposes; radiopharmaceutical products, namely, gases and gas m...