title: Gadolinium distribution in cochlear perilymph: differences between intratympanic and intravenous gadolinium injection.
abstract: BACKGROUND
  Three-dimensional fluid-attenuated inversion recovery (3D-FLAIR) imaging 24 h after intratympanic gadolinium injection (IT method) or 4 h after intravenous injection (IV method) has been used to visualize endolymphatic hydrops in Ménière's disease. The aims of this study were to evaluate the difference in gadolinium distribution in cochlear perilymph between the two methods by comparing the enhancement of the basal and apical turns and clarify the pharmacokinetics in cochlear perilymph.
  
  
  METHODS
  A total of 24 ears of 22 patients who underwent the IT method (gadolinium-diethylene-triamine pentaacetic acid was diluted eightfold with saline) and 28 ears of 17 patients who underwent the IV method (double dose of gadoteridol (0.5 mmol/ml); 0.2 mmol/kg body weight in total amount) at 3 T was analyzed retrospectively. Regions of interest of the perilymph of the cochlear basal turn (B), of the apical turn (A), and the medulla oblongata (M) were determined on each patient. The signal intensity ratios between B and M (BMR), A and M (AMR), and A and B (ABR) were subsequently evaluated.
  
  
  RESULTS
  The IT-BMR (2.63 ± 1.22) was higher than the IV-BMR (1.46 ± 0.45) (p < 0.001). There was no significant difference between the IT- (1.46 ± 0.76) and IV-AMRs (1.21 ± 0.48) (p = 0.15). The IT-ABR (0.58 ± 0.17) was lower than the IV-ABR (0.84 ± 0.22) (p < 0.001).
  
  
  CONCLUSIONS
  Gadolinium was predominantly distributed in the basal turn compared with the apical turn in the IT method, whereas it was more uniformly distributed in the IV method. These characteristics might reflect the distribution of therapeutic medications administered either intratympanically or systemically.
authors.affiliation: Department of Radiology, Nagoya University Graduate School of Medicine, 65 Tsurumai-cho, Showa-ku, Nagoya 466-8550, Japan. yamazaki@med.nagoya-u.ac.jp
authors.forename: Masahiro
authors.initials: M
authors.lastname: Yamazaki
authors.forename: Shinji
authors.initials: S
authors.lastname: Naganawa
authors.forename: Hisashi
authors.initials: H
authors.lastname: Kawai
authors.forename: Michihiko
authors.initials: M
authors.lastname: Sone
authors.forename: Tsutomu
authors.initials: T
authors.lastname: Nakashima
mesh_terms: D000293:Adolescent; D000328:Adult; D003051:Cochlea / Q000378:metabolism* / Q000473:pathology; D003287:Contrast Media / Q000008:administration & dosage / Q000493:pharmacokinetics; D005260:Female; D019786:Gadolinium DTPA / Q000008:administration & dosage / Q000031:analogs & derivatives* / Q000493:pharmacokinetics; D006801:Humans; D007275:Injections, Intravenous; D008297:Male; D008575:Meniere Disease / Q000378:metabolism* / Q000473:pathology; D008875:Middle Aged; D009829:Oleic Acids / Q000008:administration & dosage* / Q000493:pharmacokinetics*; D010498:Perilymph / Q000166:cytology / Q000378:metabolism*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D014018:Tissue Distribution; D055815:Young Adult
chemical_list: D003287:Contrast Media; D009829:Oleic Acids; C469626:gadolinium diethylene-triamine-pentaacetic acid-bis-oleate; D019786:Gadolinium DTPA