title: The image variations in mastoid segment of facial nerve and sinus tympani in congenital aural atresia by HRCT and 3D VR CT.
abstract: OBJECTIVE
  To find the variations of middle ear structures including the spatial pattern of mastoid segment of facial nerve and the shapes of the sinus tympani in patients with congenital aural atresia (CAA) by using the high-resolution (HR) CT and 3D volume rendered (VR) CT images.
  
  
  METHODS
  HRCT was performed in 25 patients with congenital aural atresia including six bilateral atresia patients (n=25, 21 males, 4 females, mean age 13.8 years, range 6-19). Along the long axis of the posterior semicircular canal ampulla, the oblique axial multiplanar reconstruction (MPR) was set to view the depiction of the round window and the mastoid segment of facial nerve. Volumetric rending technique was used to demonstrate the morphologic features. HRCT and 3D VR findings in atresia ears were compared with those in 19 normal ears of the unilateral ears of atresia patients.
  
  
  RESULTS
  On the basic plane, the horizontal line distances between the mastoid segment of the facial nerve and the round window (h-RF) in atresia ears significantly decreased compared to the control ears (P<0.05). There was a significant negative correlation between the sinus tympani area (a-ST) and the distance between the horizontal lines of FN and RW midpoint (h-RF) (P<0.05). The mean area of sinus tympani in atresia group is larger (P<0.05). The shapes of the sinus tympani were classified into three categories: the cup-shaped, the pear-shaped and the boot-shaped. Area measurement indicated that the boot-shaped sinus tympani was a special variation with a large area, which only appears in CAA group. There were a significant difference between the area of the boot-shaped group and the other two groups (P<0.05). The morphologic differences of ST and other middle ear structures can also be observed visually in 3D VR CT images.
  
  
  CONCLUSIONS
  HRCT and 3D VR CT could help a better understanding of different kinds of variations in mastoid segment of facial nerve and sinus tympani in CAA ears. And it may further help surgeons to make the correct decision for hearing rehabilitation.
authors.affiliation: Department of Otolaryngology, Peking Union Medical College Hospital, Beijing, PR China.
authors.forename: Zhen
authors.initials: Z
authors.lastname: Wang
authors.affiliation: Department of Otolaryngology, Peking Union Medical College Hospital, Beijing, PR China.
authors.forename: Qian
authors.initials: Q
authors.lastname: Hou
authors.affiliation: Department of Otolaryngology, Peking Union Medical College Hospital, Beijing, PR China.
authors.forename: Pu
authors.initials: P
authors.lastname: Wang
authors.affiliation: Department of Radiology, Peking Union Medical College Hospital, Beijing, PR China.
authors.forename: Zhaoyong
authors.initials: Z
authors.lastname: Sun
authors.affiliation: Department of Otolaryngology, Peking Union Medical College Hospital, Beijing, PR China.
authors.forename: Yue
authors.initials: Y
authors.lastname: Fan
authors.affiliation: Department of Radiology, Peking Union Medical College Hospital, Beijing, PR China.
authors.forename: Yun
authors.initials: Y
authors.lastname: Wang
authors.affiliation: Department of Radiology, Peking Union Medical College Hospital, Beijing, PR China.
authors.forename: Huadan
authors.initials: H
authors.lastname: Xue
authors.affiliation: Department of Radiology, Peking Union Medical College Hospital, Beijing, PR China.
authors.forename: Zhengyu
authors.initials: Z
authors.lastname: Jin
authors.affiliation: Department of Otolaryngology, Peking Union Medical College Hospital, Beijing, PR China. Electronic address: chenxw_pumch@163.com.
authors.forename: Xiaowei
authors.initials: X
authors.lastname: Chen
mesh_terms: D000293:Adolescent; D002648:Child; D000013:Congenital Abnormalities / Q000000981:diagnostic imaging*; D004423:Ear / Q000002:abnormalities* / Q000000981:diagnostic imaging; D004432:Ear, Middle / Q000002:abnormalities / Q000000981:diagnostic imaging*; D005154:Facial Nerve / Q000002:abnormalities* / Q000000981:diagnostic imaging; D005260:Female; D006801:Humans; D021621:Imaging, Three-Dimensional / Q000379:methods*; D008297:Male; D008416:Mastoid / Q000000981:diagnostic imaging; D012189:Retrospective Studies; D014057:Tomography, X-Ray Computed / Q000379:methods*; D055815:Young Adult
keywords: Congenital aural atresia; Ear surgery; Facial nerve; High resolution computed tomography (HRCT); Temporal bone