title: Evaluation of Auditory Pathways Using DTI in Patients Treated with Gamma Knife Radiosurgery for Acoustic Neuroma: A Preliminary Report.
abstract: OBJECTIVE
  We aimed to evaluate the change in bilateral auditory pathways using diffusion tensor imaging (DTI) after gamma knife radiosurgery (GKR) and to determine the relationship between the radiosurgical treatment variables and DTI findings.
  
  
  METHODS
  In this study 13 patients with unilateral acoustic neuroma and 11 controls underwent routine magnetic resonance imaging (MRI) and DTI. The apparent diffusion coefficient (ADC) and fractional anisotropy (FA) were measured from the bilateral auditory pathways in all individuals before and after GKR.
  
  
  RESULTS
  Before GKR, subjects' ADC values obtained from the contralateral side were higher at the lateral lemniscus, medial geniculate body and Heschl's gyrus compared to those of the controls. No statistical differences were found in ADC and FA obtained at bilateral auditory pathways before and after GKR. The ADCs measured at the lateral lemniscus were positively correlated with the maximum radiation dose delivered to the brainstem (BS) and the brainstem volume receiving a radiation dose of 10 Gy (BS V10). A negative correlation was found between the FA measured from the inferior colliculus and the maximum radiation dose to the cochlea. The ADCs at the inferior colliculus were positively correlated with the mean radiation dose to the cochlea.
  
  
  CONCLUSIONS
  There were no significant differences in the degree of involvement before and after GKR, revealing that GKR did not significantly affect the auditory pathways at 4 months. The major factors that may lead to microstructural injury to auditory pathways at the brainstem level are associated with maximum brainstem radiation dose, BS V10, and cochlear dose. These findings may suggest that more attention should be paid to anatomical structures including the cochlea and brainstem during treatment planning of GKR.
authors.affiliation: Department of Radiology, Faculty of Medicine, Bezmialem Vakif University, 34093, Istanbul, Turkey. s.kurtcan@hotmail.com.
authors.forename: Serpil
authors.initials: S
authors.lastname: Kurtcan
authors.affiliation: Department of Neurosurgery, Faculty of Medicine, BezmialemVakif University, Istanbul, Turkey.
authors.forename: Mustafa Aziz
authors.initials: MA
authors.lastname: Hatiboglu
authors.affiliation: Department of Radiology, Faculty of Medicine, Bezmialem Vakif University, 34093, Istanbul, Turkey.
authors.forename: Alpay
authors.initials: A
authors.lastname: Alkan
authors.affiliation: Department of Radiology, Faculty of Medicine, Bezmialem Vakif University, 34093, Istanbul, Turkey.
authors.forename: Huseyin
authors.initials: H
authors.lastname: Toprak
authors.affiliation: Department of Neurosurgery, Faculty of Medicine, BezmialemVakif University, Istanbul, Turkey.
authors.forename: Mehmet Hakan
authors.initials: MH
authors.lastname: Seyithanoglu
authors.affiliation: Department of Radiology, Faculty of Medicine, Bezmialem Vakif University, 34093, Istanbul, Turkey.
authors.forename: Ayse
authors.initials: A
authors.lastname: Aralasmak
authors.affiliation: Department of Radiology, Faculty of Medicine, Bezmialem Vakif University, 34093, Istanbul, Turkey.
authors.forename: Bahar
authors.initials: B
authors.lastname: Atasoy
authors.affiliation: Department of Biostatistics, Faculty of Medicine, BezmialemVakif University, Istanbul, Turkey.
authors.forename: Omer
authors.initials: O
authors.lastname: Uysal
mesh_terms: D000328:Adult; D000368:Aged; D001306:Auditory Pathways / Q000000981:diagnostic imaging*; D056324:Diffusion Tensor Imaging; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009464:Neuroma, Acoustic / Q000000981:diagnostic imaging* / Q000601:surgery; D016634:Radiosurgery
keywords: Acoustic neuroma; Auditory pathway; DTI; Gamma knife radiosurgery; Microstructural injury