Inclusion Criteria:  Proven or highly suspected to have a head and neck tumour, including oral cavity cancer, and/or abnormal LN in the head and neck (on the basis of physical examination or medical imaging). 18 years or older (no upper age limit).  Exclusion Criteria:  Unable to provide informed written informed consent (e.g. dementia, significant mental illness, brain metastases). Severe skin or mucosal disease precluding safe, comfortable placement of the US or PAT probes (e.g. active infection; ulcerating tumour). Contraindication to MRI magnetic field e.g. non-MRI compatible pacemaker, cochlear implant, severe claustrophobia, or allergy to MRI contrast agent (Gadolinium) Restricted mouth opening in those patients with an oral cavity neoplasm