title: Role of diffusion-weighted MR imaging in assessing malignant versus benign skull-base lesions.
abstract: OBJECTIVE
  This study was done to assess the role of diffusion-weighted magnetic resonance (MR) imaging in assessing malignant versus benign skull lesions.
  
  
  METHODS
  A retrospective analysis was undertaken of 45 patients (26 male, 19 female; age range 14-68 years, mean age 39 years) with skull-base lesions. Diffusion-weighted MR images were acquired with a b-factor of 500 and 1,000 s/mm(2) using single-shot echoplanar imaging. Apparent diffusion coefficient (ADC) maps were reconstructed, and the ADC value of the lesion was calculated.
  
  
  RESULTS
  The mean ADC value of malignant tumours was (1.002 ± 0.21) × 10(-3) mm(2)/s and that of benign tumours was (1.63 ± 0.29) × 10(-3) mm(2)/s. There was a statistically significant difference (p=0.001) in the ADC value of malignant skull-base tumours versus benign lesions. Selection of (1.3) × 10(-3)mm(2)/s as a threshold value of ADC for differentiating benign from malignant tumours yielded the best result, with an accuracy of 94%, sensitivity of 94%, specificity of 93%, positive predictive value of 93%, negative predictive value of 94% and area under the curve of 0.932.
  
  
  CONCLUSIONS
  We conclude that diffusion-weighted MR imaging is a promising, noninvasive approach that can be used to characterise skull-base lesions in that it can help differentiate malignant tumours from benign lesions and evaluate the pathological grading of malignant tumours.
authors.affiliation: Department of Diagnostic Radiology, Mansoura Faculty of Medicine, Mansoura, Egypt. arazek@mans.eun.eg
authors.forename: A
authors.initials: A
authors.lastname: Abdel Razek
authors.forename: A
authors.initials: A
authors.lastname: Mossad
authors.forename: M
authors.initials: M
authors.lastname: Ghonim
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D003287:Contrast Media; D003937:Diagnosis, Differential; D038524:Diffusion Magnetic Resonance Imaging / Q000379:methods*; D005260:Female; D006801:Humans; D007090:Image Interpretation, Computer-Assisted; D008297:Male; D008875:Middle Aged; D012372:ROC Curve; D012189:Retrospective Studies; D012680:Sensitivity and Specificity; D019292:Skull Base Neoplasms / Q000175:diagnosis*
chemical_list: D003287:Contrast Media