title: Dynamic enhancement of the rat inner ear after ultra-small-volume administration of Gd-DOTA to the medial wall of the middle ear cavity.
abstract: OBJECTIVE
  To investigate minimally invasive administration of contrast agent to the middle ear and the enhancement efficacy on the inner ear compartments.
  
  
  METHODS
  An ultra-small volume of gadolinium-tetraazacyclododecane tetraacetic acid (Gd-DOTA) was injected onto the medial wall of the rat middle ear with a high-performance polyimide tube. The dynamic Gd-DOTA distribution in the inner ear was visualized in vivo by MRI.
  
  
  RESULTS
  After injection of 2.5 μl of 0.5MGd-DOTA, uptake first occurred in the vestibulum, then in the scala vestibuli, and finally in the scala tympani (ST). A significant difference in signal intensities among these compartments was demonstrated with an intensity gradient, indicating that the vestibulum was the highest and the ST was the lowest. After 24 h, Gd-DOTA remained in the inner ear and the vestibule remained higher compared to the cochlea. The signal/noise ratio was significantly improved by a fluid-attenuated inversion recovery sequence.
  
  
  CONCLUSIONS
  This novel minimally invasive technique can be applied to both animal studies and clinical evaluations of inner ear barrier function and fluid spaces with gadolinium-enhanced MRI. This technique might also be exploited for use as a minimally invasive drug delivery means for inner ear treatment.
authors.affiliation: Department of Otolaryngology, University of Tampere, Medical School, Tampere, Finland. Jing.Zou@uta.fi
authors.forename: Jing
authors.initials: J
authors.lastname: Zou
authors.forename: Tadao
authors.initials: T
authors.lastname: Yoshida
authors.forename: Usama A
authors.initials: UA
authors.lastname: Ramadan
authors.forename: Ilmari
authors.initials: I
authors.lastname: Pyykkö
mesh_terms: D000818:Animals; D003287:Contrast Media / Q000008:administration & dosage; D004195:Disease Models, Animal; D004427:Ear Diseases / Q000175:diagnosis*; D007758:Ear, Inner / Q000473:pathology*; D004432:Ear, Middle / Q000473:pathology*; D005682:Gadolinium; D006571:Heterocyclic Compounds / Q000008:administration & dosage; D007267:Injections; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D009942:Organometallic Compounds / Q000008:administration & dosage; D051381:Rats; D017208:Rats, Wistar; D015203:Reproducibility of Results
chemical_list: D003287:Contrast Media; D006571:Heterocyclic Compounds; D009942:Organometallic Compounds; C050823:gadolinium 1,4,7,10-tetraazacyclododecane-N,N',N'',N'''-tetraacetate; D005682:Gadolinium