title: Differences in perilymphatic space enhancement and adverse inflammatory reaction after intratympanic injection of two different gadolinium agents: A 9.4-T magnetic resonance imaging study.
abstract: OBJECTIVE
  To compare the inner ear enhancement after intratympanic injection of two widely used gadolinium (Gd) agents by 9.4 T micro-magnetic resonance imaging (MRI) and to investigate the effects of Gd on the inner ear.
  
  
  METHODS
  Twelve ears of six rats received intratympanic administration of 1/5 diluted Gd agents: gadoterate meglumine (Gd-DTPA) for the left ear and gadodiamide (Gd-DTPA-BMA) for the right ear. MRI was performed every 30 min from 1 to 4 h after administration. The normalized signal intensity was evaluated by quantitative analysis at each cochlear fluid compartment. Eight, six, and seven ears treated with Gd-DTPA, Gd-DPTA-BMA, and nothing as controls, respectively, were processed for histological evaluation after MRI. After hematoxylin & eosin staining, adverse inflammatory reactions were evaluated for turbid aggregation and lymphocytes.
  
  
  RESULTS
  The perilymphatic enhancement of Gd-DTPA was superior to that of Gd-DTPA-BMA regardless of cochlear turn, compartment, and time point. Inflammatory reactions were found in 4/8 (50.0%) and 4/6 (66.6%) ears administered Gd-DTPA and Gd-DTPA-BMA, respectively. Regardless of the contrast agent used, inflammatory reactions were most definite in the scala tympani of the basal turn, i.e., near the round window. Slightly greater inflammatory reactions were observed in ears injected with Gd-DTPA-BMA compared to Gd-DTPA although the difference was not statistically significant. No inflammatory reaction was observed in any of the seven controls. The auditory brainstem response threshold was 11.8 ± 2.5 dB SPL before IT Gd injection and it did not change for up to 5 days (15.4 ± 6.6 dB SPL) post-injection.
  
  
  CONCLUSIONS
  Gd-DTPA was superior to Gd-DTPA-BMA for visualization of the inner ear. Administration of diluted Gd agents intratympanically may induce considerable inflammatory reactions in the inner ear.
authors.affiliation: Department of Otorhinolaryngology-Head and Neck Surgery and Healthcare Research Institute, Healthcare System Gangnam Center, Seoul National University Hospital, Seoul, Republic of Korea; Department of Translational Biomedical Research, Seoul National University College of Medicine, Seoul, Republic of Korea.
authors.forename: Mina
authors.initials: M
authors.lastname: Park
authors.affiliation: Department of Otorhinolaryngology-Head and Neck Surgery, Seoul National University Hospital, Seoul, Republic of Korea.
authors.forename: Ho Sun
authors.initials: HS
authors.lastname: Lee
authors.affiliation: Radiology, Seoul National University Hospital, Seoul, Republic of Korea; Department of Biomedical Sciences, Seoul National University, Seoul, Republic of Korea.
authors.forename: Hyeonjin
authors.initials: H
authors.lastname: Kim
authors.affiliation: Department of Otorhinolaryngology-Head and Neck Surgery, Seoul National University Hospital, Seoul, Republic of Korea; Department of Otorhinolaryngology-Head and Neck Surgery, Seoul National University College of Medicine, Seoul, Republic of Korea; Sensory Organ Research Institute, Seoul National University Medical Research Center, Seoul, Republic of Korea.
authors.forename: Seung Ha
authors.initials: SH
authors.lastname: Oh
authors.affiliation: Department of Otorhinolaryngology-Head and Neck Surgery, Seoul National University Hospital, Seoul, Republic of Korea; Department of Otorhinolaryngology-Head and Neck Surgery, Seoul National University College of Medicine, Seoul, Republic of Korea; Sensory Organ Research Institute, Seoul National University Medical Research Center, Seoul, Republic of Korea.
authors.forename: Jun Ho
authors.initials: JH
authors.lastname: Lee
authors.affiliation: Department of Otorhinolaryngology-Head and Neck Surgery, Seoul National University Hospital, Seoul, Republic of Korea; Sensory Organ Research Institute, Seoul National University Medical Research Center, Seoul, Republic of Korea. Electronic address: drmung@naver.com.
authors.forename: Myung-Whan
authors.initials: MW
authors.lastname: Suh
mesh_terms: D000818:Animals; D003052:Cochlear Aqueduct / Q000187:drug effects* / Q000473:pathology; D003287:Contrast Media / Q000008:administration & dosage / Q000633:toxicity*; D007758:Ear, Inner / Q000187:drug effects* / Q000473:pathology; D019786:Gadolinium DTPA / Q000008:administration & dosage / Q000633:toxicity*; D000069555:Injection, Intratympanic; D007762:Labyrinthitis / Q000139:chemically induced* / Q000473:pathology; D008279:Magnetic Resonance Imaging; D017207:Rats, Sprague-Dawley; D013997:Time Factors
chemical_list: D003287:Contrast Media; C064925:gadodiamide; D019786:Gadolinium DTPA
keywords: Gadolinium; Inner ear; Magnetic resonance imaging; Rat; Toxicity