In this study the possible changes in upper airway geometry induced by variations in the characteristics of the mouthpieces of inhalers will be evaluated with functional respiratory imaging (FRI) and Pharyngometry. The study population consists of 12 healthy male subjects.

Different mouthpiece designs will be evaluated for each subject by using magnetic resonance imaging (MRI) scans. The results will help to identify the influence of the height, width, protrusion and resistance of the mouthpiece on upper airway geometry.

Pharyngometry profiles of all subjects, whilst inhaling through different mouthpiece variants, in supine and upright position, will be completed.

A computed tomography (CT) scan and a cone beam computed tomography (CBCT) scan of the upper airway will be taken to respectively compare the time dependence on 3D imaging with MRI and to provide a 3D image in an upright position.

Dental impressions will be optically scanned to obtain a more accurate representation of the oral cavity, mainly in MRI.

Inclusion Criteria:

• Male subject ≥ 18 years old
• Written informed consent obtained
• BMI ≥ 20 kg/m2 and < 25 kg/m2
• Height ≥ 175 cm and ≤ 185 cm
• Subject must be able to understand and complete the protocol requirements, instructions and protocol-stated restrictions.

Exclusion Criteria:

• Subject with claustrophobia
• Subject with a history of surgery of the upper airway
• Subject with an enlarged thyroid gland
• Subject with intra-oral piercings
• Subject with dental bracket
• Subject with a pacemaker or another implant that is likely to interfere with the MRI procedure
• Subject that is unlikely to comply with the protocol or unable to understand the nature, scope and possible consequences of the study
• Subject who received any investigational new drug within the last 4 weeks prior to visit 1.