title: A survey analysis of acoustic trauma related to MR scans.
abstract: OBJECTIVE
  The maximum limit of MR scanner noise and necessity of ear protection is defined in the IEC standard (IEC60601-2-33) of MR safety. With improvements in MR scanner performance, pulse sequences generating higher scanning noise have been used clinically. In this study, we investigated the factors significantly related to potential acoustic trauma cases (PATC) after MR examinations. To consider the future direction for MR safety and prevention of acoustic trauma, issues related to noise generation by MR scanners and acoustic trauma were systematically reviewed.
  
  
  METHODS
  A statistical analysis was performed using the data set from a survey (n=974) conducted in 2010 by the JSMRM safety committee. Hierarchical clustering analysis was used to extract the characteristics of the responders. With this classification as a reference, tests of independence and a residual analysis were employed to evaluate the factors related to PATC.
  
  
  RESULTS
  No significant relationship was observed between the ear protection policy and the incidence or the reported outcome of PATC. While the two main clusters out of the six clusters extracted were associated with who reported the PATC and the confirmation process of the acoustic noise level of MR scanners, no cluster was associated with the frequency of PATC. An absence of PATC was significantly less reported (p=0.03) and more PATC was reported (p=0.04) by facilities with 3T MR systems.
  
  
  CONCLUSIONS
  Although the total frequency was 4 cases, it should be noted that persistent hearing disturbances are a possible consequence of MR examinations. Neither the condition of the subjects nor the ear protection method was significantly related to the probability of PATC, suggesting the difficulty of predicting the potential risk of acoustic trauma. It is recommended to more systematically follow up PATC cases and clarify the risk factors.
authors.affiliation: Neuroinformatics & Imaging, National Center for Geriatrics and Gerontology, Gengo, Aich, Japan. toshi@ncgg.go.jp
authors.forename: Toshiharu
authors.initials: T
authors.lastname: Nakai
authors.forename: Naoki
authors.initials: N
authors.lastname: Kamiya
authors.forename: Michihiko
authors.initials: M
authors.lastname: Sone
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Muranaka
authors.forename: Toshio
authors.initials: T
authors.lastname: Tsuchihashi
authors.forename: Naoki
authors.initials: N
authors.lastname: Yamada
authors.forename: Sachiko
authors.initials: S
authors.lastname: Yamaguchi
mesh_terms: D000328:Adult; D000368:Aged; D004430:Ear Protective Devices / Q000706:statistics & numerical data*; D005260:Female; D006282:Health Personnel / Q000706:statistics & numerical data*; D006317:Hearing Loss, Noise-Induced / Q000209:etiology* / Q000517:prevention & control*; D006801:Humans; D008279:Magnetic Resonance Imaging / Q000009:adverse effects* / Q000379:methods; D008297:Male; D008875:Middle Aged; D009622:Noise / Q000009:adverse effects*; D012449:Safety / Q000706:statistics & numerical data; D011795:Surveys and Questionnaires; D055815:Young Adult