title: Utility of pretreatment mean apparent diffusion coefficient and apparent diffusion coefficient histograms in prediction of outcome to chemoradiation in head and neck squamous cell carcinoma.
abstract: OBJECTIVE
  This study aimed to evaluate pretreatment whole-tumor mean apparent diffusion coefficient (ADC) and ADC histogram as predictors of outcome to chemoradiation in patients with head and neck squamous cell carcinoma (HNSCC).
  
  
  METHODS
  Patients with HNSCC underwent pretreatment 3-T diffusion-weighted magnetic resonance imaging with calculation of mean ADC and ADC histograms. Outcomes were determined 2 years after chemoradiation. Positive outcome was defined as no abnormal 18-fluoro deoxy glucose uptake on posttherapy computed tomography-positron emission tomography (or abnormal uptake that was proven benign), no locoregional recurrence or metastatic disease, and no requirement for salvage surgery. Negative outcome was defined as residual abnormal 18-fluoro deoxy glucose avidity that was proven malignant, salvage surgery requirement, locoregional recurrence or metastatic disease, death, or a combination of these. A 2-sample t test was used to compare the mean ADC between patients with positive and negative outcomes. The ADC cut point for dividing the groups was determined by looking at its distribution. A Kaplan-Meier plot was produced, and a log-rank test was conducted with calculation of sensitivity, specificity, and positive and negative predictive values.
  
  
  RESULTS
  Nine patients showed positive and 8 showed negative outcomes. Significant difference (P = 0.03) was seen in mean ADC (in 10 mm/s) between patients showing positive and negative outcomes (1.18 and 1.43, respectively). According to the log-rank test, tumors with greater than 45% of their volume below the ADC threshold of 1.15 × 10 mm/s were more likely to have a positive outcome (accuracy, 77%).
  
  
  CONCLUSIONS
  Patients with HNSCC demonstrating lower pretreatment ADC and with greater than 45% of volume below ADC threshold of 1.15 × 10 mm/s may have better outcome to chemoradiation at 2 years.
authors.affiliation: Division of Neuroradiology, Department of Radiology, University of Michigan Health System, Ann Arbor, MI 48109, USA. ashoks@med.umich.edu
authors.forename: Ashok
authors.initials: A
authors.lastname: Srinivasan
authors.forename: Thomas L
authors.initials: TL
authors.lastname: Chenevert
authors.forename: Ben A
authors.initials: BA
authors.lastname: Dwamena
authors.forename: Avraham
authors.initials: A
authors.lastname: Eisbruch
authors.forename: Kuanwong
authors.initials: K
authors.lastname: Watcharotone
authors.forename: James D
authors.initials: JD
authors.lastname: Myles
authors.forename: Suresh K
authors.initials: SK
authors.lastname: Mukherji
mesh_terms: D001772:Blood Cell Count; D002294:Carcinoma, Squamous Cell / Q000000981:diagnostic imaging / Q000473:pathology / Q000628:therapy*; D059248:Chemoradiotherapy; D003287:Contrast Media; D038524:Diffusion Magnetic Resonance Imaging / Q000379:methods*; D005260:Female; D006258:Head and Neck Neoplasms / Q000000981:diagnostic imaging / Q000473:pathology / Q000628:therapy*; D006801:Humans; D007090:Image Interpretation, Computer-Assisted; D008111:Liver Function Tests; D008297:Male; D008875:Middle Aged; D064847:Multimodal Imaging; D049268:Positron-Emission Tomography; D011237:Predictive Value of Tests; D012680:Sensitivity and Specificity; D014057:Tomography, X-Ray Computed; D016896:Treatment Outcome
chemical_list: D003287:Contrast Media