title: Relative proportions of stromal to cellular components of pleomorphic adenomas: determination with shear wave elastography.
abstract: OBJECTIVE
  The purpose of this study was to evaluate whether the relative proportions of stromal to cellular components of pleomorphic adenomas have an effect on the shear elastic modulus determined by shear wave elastography (SWE).
  
  
  METHODS
  This study was approved by the Ethics Committee of our institution and performed between September 2011 and December 2012. Thirty-five patients who underwent surgery for a parotid mass were included in the study. The maximum shear elastic modulus of the mass was measured by SWE. Pleomorphic adenomas were histopathologically subdivided into stroma-poor, intermediate-stroma, and stroma-rich tumors based on the relative proportion of stromal to cellular components.
  
  
  RESULTS
  The maximum shear elastic modulus values of the pleomorphic adenomas ranged from 12.6 to 291.9 kPa (mean ± SD, 120.9 ± 92.8 kPa). The Friedman test revealed a statistically significant relationship between the stromal amount and maximum shear elastic modulus (P < .001). Stroma-poor adenomas (mean, 32.3 ± 27.7 kPa; range, 12.6-81.1 kPa) were softer on SWE than stroma-rich adenomas (mean, 174.1 ± 48.4 kPa; range, 92.7-217.2 kPa; P = .009). No such significant difference was detected between stroma-poor and intermediate-stroma tumors (mean, 146.3 ± 106.1 kPa; range, 19.1-291.9 kPa; P = .062) or between intermediate-stroma and stroma-rich tumors (P = .465).
  
  
  CONCLUSIONS
  Shear wave elastography depicts pleomorphic adenomas with a variable appearance, which is due to the relative proportions of stromal to cellular contents in the tumors.
authors.affiliation: Department of Radiology, Istanbul University, Cerrahpasa Medical Faculty, Kocamustafapasa, 34300 Istanbul, Turkey. iadaletli@yahoo.com.
authors.forename: Deniz Cebi
authors.initials: DC
authors.lastname: Olgun
authors.forename: Fatih
authors.initials: F
authors.lastname: Kantarci
authors.forename: Umit
authors.initials: U
authors.lastname: Taskin
authors.forename: Fahrettin
authors.initials: F
authors.lastname: Kilic
authors.forename: Mehmet Faruk
authors.initials: MF
authors.lastname: Oktay
authors.forename: Serdar
authors.initials: S
authors.lastname: Altinay
authors.forename: Nuray
authors.initials: N
authors.lastname: Kepil
authors.forename: Ibrahim
authors.initials: I
authors.lastname: Adaletli
authors.forename: Mehmet
authors.initials: M
authors.lastname: Ada
authors.forename: Ismail
authors.initials: I
authors.lastname: Mihmanli
mesh_terms: D008949:Adenoma, Pleomorphic / Q000000981:diagnostic imaging* / Q000473:pathology*; D000328:Adult; D054459:Elasticity Imaging Techniques / Q000379:methods*; D005260:Female; D006801:Humans; D007090:Image Interpretation, Computer-Assisted / Q000379:methods; D008297:Male; D008875:Middle Aged; D010307:Parotid Neoplasms / Q000000981:diagnostic imaging* / Q000473:pathology*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D017154:Stromal Cells / Q000000981:diagnostic imaging* / Q000473:pathology*
keywords: general ultrasound; neoplasms; parotid gland; pleomorphic adenoma; shear wave elastography; sonography