title: Dual-Energy CT-Based Differentiation of Benign Posttreatment Changes From Primary or Recurrent Malignancy of the Head and Neck: Comparison of Spectral Hounsfield Units at 40 and 70 keV and Iodine Concentration.
abstract: OBJECTIVE
  The goals of our study were to evaluate dual-energy CT (DECT) differences between benign posttreatment changes and primary or recurrent head and neck malignancies in terms of spectral Hounsfield units for virtual monochromatic series at 40 keV and iodine concentration and compare their utility with that of spectral Hounsfield units at 70 keV.
  
  
  METHODS
  A retrospective review of patients with a history of head and neck malignancy evaluated with DECT of the neck from November 2012 through December 2014 revealed 16 patients with benign posttreatment changes and 24 with malignancies (17 primary tumors and seven recurrent tumors). One reader placed ROIs within benign posttreatment changes or malignant tumors in each patient to generate spectral Hounsfield units at 40 keV, iodine concentration, and spectral Hounsfield units at 70 keV, and the Wilcoxon rank sum test was used to evaluate the differences between the two cohorts. ROC curves were also generated, and AUC and partial AUC were calculated at the three following specificities: 75%, 80%, and 90%.
  
  
  RESULTS
  Malignant tissues were significantly different from benign posttreatment changes in spectral Hounsfield units at 40 keV (p < 0.0001), iodine concentration (p < 0.0001), and spectral Hounsfield units at 70 keV (p = 0.0001). The AUCs were 0.949, 0.943, and 0.858 for spectral Hounsfield units at 40 keV, iodine concentration, and spectral Hounsfield units at 70 keV, respectively. Both spectral Hounsfield units at 40 keV and iodine concentration had statistically higher partial AUCs than spectral Hounsfield units at 70 keV at 90% specificity (p = 0.0133 and 0.0063, respectively) but were not significantly different from each other.
  
  
  CONCLUSIONS
  DECT-derived spectral Hounsfield units at 40 keV and iodine concentration may be superior to spectral Hounsfield units at 70 keV, which is similar to MDCT, in differentiating benign posttreatment changes from primary or recurrent head and neck malignancies.
authors.affiliation: 1 Department of Radiology, The Jikei University School of Medicine, Tokyo, Japan.
authors.forename: Hideomi
authors.initials: H
authors.lastname: Yamauchi
authors.affiliation: 2 Department of Radiology, Toledo University, Toledo, OH.
authors.forename: Mark
authors.initials: M
authors.lastname: Buehler
authors.affiliation: 3 Department of Radiology, University of Michigan Health System, Ann Arbor, MI.
authors.forename: Mitchell M
authors.initials: MM
authors.lastname: Goodsitt
authors.affiliation: 4 Michigan Institute for Clinical & Health Research, University of Michigan, Ann Arbor, MI.
authors.forename: Nahid
authors.initials: N
authors.lastname: Keshavarzi
authors.affiliation: 5 Department of Radiology, Division of Neuroradiology, University of Michigan Health System, 1500 E Medical Center Dr, Ann Arbor, MI 48109.
authors.forename: Ashok
authors.initials: A
authors.lastname: Srinivasan
mesh_terms: D000368:Aged; D003287:Contrast Media / Q000032:analysis; D003937:Diagnosis, Differential; D005260:Female; D006258:Head and Neck Neoplasms / Q000000981:diagnostic imaging*; D006801:Humans; D007091:Image Processing, Computer-Assisted; D017613:Iodine Compounds / Q000032:analysis; D008297:Male; D008875:Middle Aged; D061330:Multidetector Computed Tomography; D009364:Neoplasm Recurrence, Local / Q000000981:diagnostic imaging*; D012189:Retrospective Studies; D014057:Tomography, X-Ray Computed / Q000379:methods*
chemical_list: D003287:Contrast Media; D017613:Iodine Compounds
keywords: dual-energy CT; head and neck malignancy; spectral Hounsfield units