title: Imaging of the Eustachian tube and its function: a systematic review.
abstract: BACKGROUND
  The Eustachian tube is a complex and inaccessible structure, which maintains middle ear ventilation to facilitate transmission of sound from the tympanic membrane to the cochlea. A renewed interest in treatments for eustachian tube dysfunction has led to a demand for methods of imaging the Eustachian tube, and assessing tube opening non-invasively. This review aims to summarise the use of imaging in the anatomical assessment of the Eustachian tube, and to explore how radiological techniques can be used to assess tube function.
  
  
  METHODS
  A systematic review of the literature was performed with narrative data analysis.
  
  
  RESULTS
  With high-resolution images, the soft and bony anatomy of the Eustachian tube can be assessed in detail. CT and MRI are best suited to identifying features associated with obstructive or patulous Eustachian tube dysfunction, though true assessments of function have only been achieved with contrast enhanced radiographs and scintigraphy. A single modality has yet to provide a complete assessment. No test has entered routine clinical use, but further development and research is underway.
  
  
  CONCLUSIONS
  Significant information can be gained from imaging the Eustachian tube, and as faster acquisition techniques are developed, it is possible that dynamic imaging of tubal opening could play an important role in the assessment of patients with ET dysfunction.
authors.affiliation: Department of ENT Surgery, Addenbrooke's Hospital, Cambridge University Hospitals NHS Foundation Trust, Hills Road, Cambridge, CB2 0QQ, UK. mes39@cam.ac.uk.
authors.forename: M E
authors.initials: ME
authors.lastname: Smith
authors.affiliation: Department of Radiology, Addenbrooke's Hospital, Cambridge University Hospitals NHS Foundation Trust, Hills Road, Cambridge, CB2 0QQ, UK.
authors.forename: D J
authors.initials: DJ
authors.lastname: Scoffings
authors.affiliation: Department of ENT Surgery, Addenbrooke's Hospital, Cambridge University Hospitals NHS Foundation Trust, Hills Road, Cambridge, CB2 0QQ, UK.
authors.forename: J R
authors.initials: JR
authors.lastname: Tysome
mesh_terms: D003937:Diagnosis, Differential; D004427:Ear Diseases / Q000000981:diagnostic imaging* / Q000473:pathology / Q000503:physiopathology*; D005064:Eustachian Tube / Q000000981:diagnostic imaging* / Q000473:pathology / Q000503:physiopathology*; D006801:Humans; D007089:Image Enhancement / Q000379:methods; D007090:Image Interpretation, Computer-Assisted / Q000379:methods*; D008279:Magnetic Resonance Imaging / Q000379:methods*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D014057:Tomography, X-Ray Computed / Q000379:methods*
keywords: Anatomy; Diagnostic imaging; Eustachian tube; Radiology