title: Role of diffusion-weighted magnetic resonance imaging in differentiation between the viable and necrotic parts of head and neck tumors.
abstract: BACKGROUND
  Differentiation between the viable and necrotic parts of a tumor is essential for accurate biopsy results and for treatment planning.
  
  
  OBJECTIVE
  To determine the role of diffusion-weighted magnetic resonance (MR) imaging in differentiation between the viable and necrotic parts of head and neck tumors.
  
  
  METHODS
  Thirty patients with malignant head and neck tumors underwent postcontrast MR imaging. Diffusion MR imaging was done on a 1.5T unit using multislice single-shot echo-planar imaging. Diffusion-weighted MR images were acquired with a diffusion-weighted factor b of 0, 500, and 1000 s/mm(2), and an apparent diffusion coefficient (ADC) map was reconstructed. The ADC value was measured within the enhanced and nonenhanced part of the tumor, and the mean ADC values were calculated. The ADC value was correlated with biopsy results.
  
  
  RESULTS
  The mean ADC value of a viable part of the tumor was 1.17+/-0.33 x 10(-3) mm(2)/s, and of the necrotic parts of the tumor 2.11+/-0.05 x 10(-3) mm(2)/s. The difference in the ADC value between the viable and necrotic parts of the head and neck tumors was statistically significant (P<0.001). Sensitivity, specificity, and accuracy of the ADC value were 92.9%, 93%, and 94.6%, respectively.
  
  
  CONCLUSIONS
  Creation of an ADC map is an excellent method for differentiation between the viable and necrotic parts of head and neck tumors. Thus, the ADC map can be used to select the best biopsy site and to detect tumor viability in post-treatment follow-up of patients after radiation therapy.
authors: Department of Diagnostic Radiology, Department of ENT and Head and Neck Surgery, Mansoura Faculty of Medicine, Mansoura, Egypt. arazek@mans.eun.eg
authors: A A K Abdel
authors: AA
authors: Razek
authors: A Salam
authors: AS
authors: Megahed
authors: A
authors: A
authors: Denewer
authors: A
authors: A
authors: Motamed
authors: A
authors: A
authors: Tawfik
authors: N
authors: N
authors: Nada
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D003287:Contrast Media / Q000008:administration & dosage; D003937:Diagnosis, Differential; D038524:Diffusion Magnetic Resonance Imaging / Q000379:methods*; D017352:Echo-Planar Imaging / Q000379:methods*; D005260:Female; D019786:Gadolinium DTPA; D006257:Head / Q000473:pathology; D006258:Head and Neck Neoplasms / Q000175:diagnosis* / Q000473:pathology; D006801:Humans; D007089:Image Enhancement / Q000379:methods; D008297:Male; D008875:Middle Aged; D009333:Neck / Q000473:pathology; D009336:Necrosis; D011237:Predictive Value of Tests; D011446:Prospective Studies; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity
chemical_list: D003287:Contrast Media; D019786:Gadolinium DTPA