X-ray of the face of a patient with sinusitis, a bacterial infection of the sinuses (air-filled cavities in the skull). The mucous lining of the left maxillary sinus (centre right), which is behind the cheek bone, is inflamed and congested (grainy areas). The right maxillary sinus (centre left) is not affected. Symptoms include pain and a thick nasal discharge, which may be accompanied by fever. Treatment is with decongestant and antibiotics.