CT scan 

Why?

Computed tomography (CT) is a medical imaging method using X-ray tomography created by computer processing. It provides important diagnostic information in various anatomical planes. The main advantage over MRI scanning is that it demonstrates bone as well as soft tissue features. A temporal bone CT scan will therefore show details of sinus and jaw bone problems. Airway problems and head and neck cancers are well demonstrated on CT scanning.

How?

The scanning technique involves lying still with the head in a medical “hair-dryer” capsule for approximately 20 minutes. It is a completely painless procedure.