title: Diverse patterns of perilymphatic space enhancement in the rat inner ear after intratympanic injection of two different types of gadolinium: a 9.4-tesla magnetic resonance study.
abstract: OBJECTIVE
  To compare the quality of perilymphatic enhancement in the rat inner ear after intratympanic injection of two types of gadolinium with a 9.4-tesla micro-MRI.
  
  
  METHODS
  Gadolinium was injected into the middle ear in 6 Sprague-Dawley rats via the transtympanic route. The left ear was injected with Gd-DO3A-butrol first, and then the right ear was injected with Gd-DOTA. MR images of the inner ear were acquired 1.0, 1.5, 2.0, 2.5, 3.0, 3.5, and 4 h after intratympanic (IT) injection using an Agilent MRI system 9.4T/160/AS. The normalized signal intensity was quantitatively analyzed at the scala vestibuli (SV), scala media, and scala tympani (ST) using a Marosis M-view system. Then the normalized signal intensities (SIs) were compared between the two contrast agents.
  
  
  RESULTS
  For Gd-DO3A-butrol, the SI was as low as 1.0-1.5 throughout 1-4 h at the SV and ST of the basal turn. The maximum SI was 1.5 ± 0.5 at the SV (2 h) and 1.3 ± 0.5 at the ST (2 h). For Gd-DOTA, the 1-hour postinjection SI at the basal turn was 2.5 ± 0.5 at the SV, 1.6 ± 0.3 at the ST, and 1.2 ± 0.3 at the scala media. In the apical turn, the maximum SI was reached after 2.5 h. The maximum SI in the apical turn was 1.8 ± 0.4 at the SV (3.5 h), 1.8 ± 0.4 at the ST (4 h), and 1.4 ± 0.3 at the scala media (4 h).
  
  
  CONCLUSIONS
  We were able to clearly visualize and separate the ST and SV using IT Gd and 9.4-tesla micro-MRI. We recommend using Gd-DO3A-butrol over Gd-DOTA and to perform the MRI 2.5 h after using IT Gd in the rat inner ear.
authors.forename: Mina
authors.initials: M
authors.lastname: Park
authors.forename: Ho Sun
authors.initials: HS
authors.lastname: Lee
authors.forename: Jun-Jae
authors.initials: JJ
authors.lastname: Choi
authors.forename: Hyeonjin
authors.initials: H
authors.lastname: Kim
authors.forename: Jun Ho
authors.initials: JH
authors.lastname: Lee
authors.forename: Seung Ha
authors.initials: SH
authors.lastname: Oh
authors.forename: Myung-Whan
authors.initials: MW
authors.lastname: Suh
mesh_terms: D000818:Animals; D003051:Cochlea / Q000033:anatomy & histology; D003052:Cochlear Aqueduct / Q000033:anatomy & histology*; D003053:Cochlear Duct / Q000033:anatomy & histology; D003287:Contrast Media; D006571:Heterocyclic Compounds; D000069555:Injection, Intratympanic; D008279:Magnetic Resonance Imaging; D009942:Organometallic Compounds; D051381:Rats; D017207:Rats, Sprague-Dawley; D012533:Scala Tympani / Q000033:anatomy & histology; D054738:Scala Vestibuli / Q000033:anatomy & histology
chemical_list: D003287:Contrast Media; D006571:Heterocyclic Compounds; D009942:Organometallic Compounds; C090600:gadobutrol; C050823:gadolinium 1,4,7,10-tetraazacyclododecane-N,N',N'',N'''-tetraacetate