title: Magnetic resonance imaging of guinea pig cochlea after vasopressin-induced or surgically induced endolymphatic hydrops.
abstract: OBJECTIVE
  To investigate the ability to detect the in vivo cochlear changes associated with vasopressin-induced and surgically induced endolymphatic hydrops using MRI at 3 tesla (T).
  
  
  METHODS
  Prospective, animal model.
  
  
  METHODS
  Animal laboratory.
  
  
  METHODS
  In group 1, five guinea pigs underwent post-gadolinium temporal bone MRI before and after seven and 14 days of chronic systemic administration of vasopressin by osmotic pump. In group 2, five guinea pigs underwent temporal bone MRI eight weeks after unilateral surgical ablation of the endolymphatic sac. Three-tesla high-resolution T1-weighted sequences were acquired pre- and postcontrast administration. Region of interest signal intensities of the perilymph and endolymph were analyzed manually. Quantitative evaluation of hydrops was measured histologically.
  
  
  RESULTS
  Gadolinium preferentially concentrated in the perilymph, allowing for distinction of cochlear compartments on 3.0-T MRI. The T1-weighted contrast MRI of vasopressin-induced hydropic cochlea showed significant increases in signal intensity of the endolymph and perilymph. Surgically induced unilateral hydropic cochlea also showed increased signal intensity, compared with the control cochlea of the same animal, but less of an increase than the vasopressin group. The histological degree of hydrops induced in the vasopressin group was comparable to previous studies.
  
  
  CONCLUSIONS
  In vivo postcontrast MRI of the inner ear demonstrated cochlear changes associated with chronic systemic administration of vasopressin and surgical ablation of the endolymphatic sac. Understanding the MRI appearance of endolymphatic hydrops induced by various methods contributes to the future use of MRI as a possible tool in the diagnosis and treatment of Ménière's disease.
authors.affiliation: Department of Otolaryngology-Head and Neck Surgery, University of North Carolina School of Medicine, Chapel Hill, NC 27599-7070, USA. allen_marshall@med.unc.edu
authors.forename: Allen F
authors.initials: AF
authors.lastname: Marshall
authors.forename: Valerie L
authors.initials: VL
authors.lastname: Jewells
authors.forename: Peter
authors.initials: P
authors.lastname: Kranz
authors.forename: Yeuh Z
authors.initials: YZ
authors.lastname: Lee
authors.forename: Weili
authors.initials: W
authors.lastname: Lin
authors.forename: Carlton J
authors.initials: CJ
authors.lastname: Zdanski
mesh_terms: D000818:Animals; D003051:Cochlea / Q000473:pathology* / Q000601:surgery; D003287:Contrast Media; D004195:Disease Models, Animal; D004711:Endolymphatic Duct / Q000601:surgery; D018159:Endolymphatic Hydrops / Q000175:diagnosis* / Q000209:etiology / Q000601:surgery; D004712:Endolymphatic Sac / Q000601:surgery; D005682:Gadolinium; D006168:Guinea Pigs; D008279:Magnetic Resonance Imaging; D008575:Meniere Disease / Q000175:diagnosis / Q000628:therapy; D011446:Prospective Studies; D014662:Vasoconstrictor Agents / Q000008:administration & dosage* / Q000494:pharmacology; D014667:Vasopressins / Q000008:administration & dosage* / Q000494:pharmacology
chemical_list: D003287:Contrast Media; D014662:Vasoconstrictor Agents; D014667:Vasopressins; D005682:Gadolinium