title: Effectiveness of anatomic criteria for predicting parotid tumour location.
abstract: OBJECTIVE
  We evaluated the accuracy, positive predictive value (PPV), negative predictive value (NPV), specificity and sensitivity of eight anatomic landmarks to differentiate parotid deep lobe tumours from superficial lobe tumours: the lateral margin of the retromandibular vein (RMV), a straight line from the facial nerve trunk (FN trunk) to the mandibular ramus (FN line), a straight line from the FN trunk to the RMV (tRMV), a straight line from the FN trunk to the lateral margin of the masseter (tMasseter), a straight line from the ipsilateral vertebral posterior end to the RMV (U-line), an arc with a radius of 8.5 mm centred on the mandibular ramus (Conn's arc), a straight line from the lateral surface of the masseter muscle to the lateral margin of the RMV (rMasseter) and an angle from the FN line, tumour and the lateral margin of the masseter muscle (FTM angle).
  
  
  METHODS
  A total of 181 patients with a parotid gland tumour who underwent parotidectomy at a tertiary hospital were identified retrospectively from May 2005 to May 2013. Pre-operative computed tomography and intraoperative findings were compared to evaluate each landmark.
  
  
  RESULTS
  rMasseter (accuracy: 85.5%, PPV: 90.0%, NPV: 85.12%, specificity: 98.1%, sensitivity: 22.2%) and tMasseter (accuracy: 86.3%, PPV: 80.0%, NPV: 87.1%, specificity: 97.1%, sensitivity: 44.4%) showed superior results as diagnostic criteria.
  
  
  CONCLUSIONS
  rMasseter and tMasseter were useful as anatomic landmarks to differentiate a parotid deep lobe tumour from a superficial lobe tumour.
authors.affiliation: Department of Otolaryngology-Head and Neck Surgery, Chonnam National University Medical School and Chonnam National University Hospital, Gwangju, South Korea.
authors.forename: J Y
authors.initials: JY
authors.lastname: Kim
authors.affiliation: Department of Otolaryngology-Head and Neck Surgery, Chonnam National University Medical School and Chonnam National University Hospital, Gwangju, South Korea.
authors.forename: H C
authors.initials: HC
authors.lastname: Yang
authors.affiliation: Department of Otolaryngology-Head and Neck Surgery, Chonnam National University Medical School and Chonnam National University Hospital, Gwangju, South Korea.
authors.forename: S
authors.initials: S
authors.lastname: Lee
authors.affiliation: Department of Otolaryngology-Head and Neck Surgery, Chonnam National University Medical School and Chonnam National University Hospital, Gwangju, South Korea.
authors.forename: H C
authors.initials: HC
authors.lastname: Kim
authors.affiliation: Department of Otolaryngology-Head and Neck Surgery, Chonnam National University Medical School and Chonnam National University Hospital, Gwangju, South Korea.
authors.forename: D J
authors.initials: DJ
authors.lastname: Shin
authors.affiliation: Department of Otolaryngology-Head and Neck Surgery, Chonnam National University Medical School and Chonnam National University Hospital, Gwangju, South Korea.
authors.forename: Y B
authors.initials: YB
authors.lastname: Cho
authors.affiliation: Department of Otolaryngology-Head and Neck Surgery, Chonnam National University Medical School and Chonnam National University Hospital, Gwangju, South Korea.
authors.forename: H-H
authors.initials: HH
authors.lastname: Cho
mesh_terms: D059925:Anatomic Landmarks; D005260:Female; D006801:Humans; D008297:Male; D010306:Parotid Gland / Q000033:anatomy & histology* / Q000000981:diagnostic imaging / Q000601:surgery; D010307:Parotid Neoplasms / Q000000981:diagnostic imaging / Q000473:pathology / Q000601:surgery*; D011237:Predictive Value of Tests; D012189:Retrospective Studies; D012680:Sensitivity and Specificity; D014057:Tomography, X-Ray Computed