title: Magnetic resonance imaging of the middle and inner ear after intratympanic injection of a gadolinium-containing gel.
abstract: OBJECTIVE
  To investigate the distribution and elimination of a gadolinium containing high viscosity formulation of sodium hyaluronan (HYA gel) after injection to the middle ear.
  
  
  METHODS
  The T1 contrast agent gadolinium-diethylenetriamine pentaacetic acid-bis methylamine (Gd-DTPA-BMA) was added to HYA gel and delivered to the middle ear of 13 albino guinea pigs by 3 different ways of injection. Magnetic resonance imaging was performed with a 4.7 T MRI system using a T1-weighted 3-dimentional rapid acquisition with relaxation enhancement sequence.
  
  
  RESULTS
  An injection technique where the Gd-DTPA-BMA-containing HYA gel was delivered to the middle ear through a percutaneous injection through the auditory bulla after a small incision had been made in the tympanic membrane gave the best filling of the middle ear, covering the cochlea and the region of the round window niche for 24 hours in a majority of the ears studied. Ears injected without an incision in the tympanic membrane showed an immediate uptake of Gd-DTPA-BMA in the inner ear as a sign of rupture of the round window membrane.
  
  
  CONCLUSIONS
  A percutaneous injection of a HYA gel into the tympanic bulla is distributed in a predictable way and gives a good filling of the middle ear cavity. The HYA gel remains in close vicinity to the RWM for more than 24 hours. Injection should be performed after an incision of the tympanic membrane has been made to prevent rupture of the round window membrane.
authors.affiliation: *Department of Clinical Science, Intervention and Technology, Karolinska Institutet, †Department of Otorhinolaryngology, Karolinska University Hospital, Stockholm; ‡Department of Surgical Sciences, §Department of Pharmacy, Uppsala University, Uppsala; ∥Department of Clinical Neuroscience, Karolinska Institutet, Stockholm, Sweden; ¶Department of Neurology, Harvard University, Boston, Massachusetts, U.S.A.; and #CNSP iMed Translational Sciences, AstraZeneca, Södertälje, Sweden.
authors.forename: Cecilia Engmér
authors.initials: CE
authors.lastname: Berglin
authors.forename: Göran
authors.initials: G
authors.lastname: Laurell
authors.forename: Tobias
authors.initials: T
authors.lastname: Bramer
authors.forename: Katarina
authors.initials: K
authors.lastname: Edsman
authors.forename: S Allen
authors.initials: SA
authors.lastname: Counter
authors.forename: Tomas
authors.initials: T
authors.lastname: Klason
authors.forename: Andreas
authors.initials: A
authors.lastname: Ekborn
mesh_terms: D000818:Animals; D003287:Contrast Media / Q000008:administration & dosage / Q000493:pharmacokinetics*; D007758:Ear, Inner / Q000187:drug effects* / Q000378:metabolism; D004432:Ear, Middle / Q000187:drug effects* / Q000378:metabolism; D019786:Gadolinium DTPA / Q000008:administration & dosage / Q000493:pharmacokinetics*; D006168:Guinea Pigs; D008279:Magnetic Resonance Imaging
chemical_list: D003287:Contrast Media; D019786:Gadolinium DTPA