title: Differentiation between benign and malignant orbital tumors at 3-T diffusion MR-imaging.
abstract: BACKGROUND
  To differentiate between malignant and benign orbital tumors at 3-T diffusion MR imaging.
  
  
  METHODS
  A retrospective study was conducted on 47 patients (34 males and 13 females aged 4-74 years) with orbital masses. They underwent echo-planar diffusion-weighted MR imaging of the orbit with b-factor of 0, 500, and 1,000 s/mm(2) at 3-T MR unit. Apparent diffusion coefficient (ADC) maps were reconstructed, and the ADC value of the orbital mass was calculated.
  
  
  RESULTS
  The mean ADC value of the malignant orbital tumors (0.84 ± 0.34 × 10(-3) mm(2)/s) was significantly lower (P = 0.001) than that of the benign orbital tumors (1.57 ± 0.33 × 10(-3) mm(2)/s). The selection of an ADC value of 1.15 × 10(-3) mm(2)/s as a threshold value for differentiating malignant orbital tumors from benign lesions has a sensitivity of 95%, a specificity of 91%, and an accuracy of 93%. There was a significant difference in the ADC value between well- and poorly differentiated malignancies (P = 0.005).
  
  
  CONCLUSIONS
  Apparent diffusion coefficient value at 3 T is an additional noninvasive imaging parameter that can be used for the differentiation of malignant orbital tumors from benign lesions, the characterization of some orbital tumors, as well as the grading of orbital malignancy.
authors.affiliation: Diagnostic Radiology Department, Mansoura Faculty of Medicine, Mansoura, Egypt. arazek@mans.edu.eg
authors.forename: Ahmed Abdel Khalek Abdel
authors.initials: AA
authors.lastname: Razek
authors.forename: Sahar
authors.initials: S
authors.lastname: Elkhamary
authors.forename: Amani
authors.initials: A
authors.lastname: Mousa
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D002648:Child; D002675:Child, Preschool; D003937:Diagnosis, Differential; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D008875:Middle Aged; D009918:Orbital Neoplasms / Q000473:pathology*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D055815:Young Adult