title: The usefulness of MR in establishing the diagnosis of parotid pleomorphic adenoma.
abstract: OBJECTIVE
  To assess the usefulness of MR findings in establishing a specific diagnosis of parotid pleomorphic adenoma.
  
  
  METHODS
  T1-weighted and T2-weighted MR images with and without contrast enhancement were obtained in 82 patients with parotid tumors. Imaging findings in the 38 patients in whom surgery subsequently revealed pleomorphic adenomas were compared with findings in the 44 patients who had other types of tumor. Specifically, the homogeneity, signal intensity, contrast enhancement, capsule thickness, lobulation, adenopathy, and infiltration of adjacent fat were compared among the different types of tumor. The sensitivity, specificity, positive predictive value, and negative predictive value were calculated.
  
  
  RESULTS
  A low-signal capsule on T2-weighted images and a lobulated contour characterized most pleomorphic adenomas. The sensitivity of the first finding for pleomorphic adenoma was 82%; specificity, 85%; positive predictive value, 82%; and negative predictive value, 84%. For the second finding, the sensitivity was 53%; specificity, 84%; positive predictive value, 74%; and negative predictive value, 67%.
  
  
  CONCLUSIONS
  None of the signs evaluated had perfect sensitivity and specificity. The MR findings of a complete capsule, lobulated contour, or high T2 signal intensity have a high predictive value for the diagnosis of pleomorphic adenoma.
authors.affiliation: Department of Radiology, Kansai Medical University, Osaka, Japan.
authors.forename: K
authors.initials: K
authors.lastname: Ikeda
authors.forename: T
authors.initials: T
authors.lastname: Katoh
authors.forename: S K
authors.initials: SK
authors.lastname: Ha-Kawa
authors.forename: H
authors.initials: H
authors.lastname: Iwai
authors.forename: T
authors.initials: T
authors.lastname: Yamashita
authors.forename: Y
authors.initials: Y
authors.lastname: Tanaka
mesh_terms: D008949:Adenoma, Pleomorphic / Q000175:diagnosis* / Q000473:pathology; D006801:Humans; D008279:Magnetic Resonance Imaging; D010307:Parotid Neoplasms / Q000175:diagnosis* / Q000473:pathology; D011237:Predictive Value of Tests; D012680:Sensitivity and Specificity