title: Diagnostic accuracy of ultrasonic histogram features to evaluate radiation toxicity of the parotid glands: a clinical study of xerostomia following head-and-neck cancer radiotherapy.
abstract: OBJECTIVE
  To investigate the diagnostic accuracy of ultrasound histogram features in the quantitative assessment of radiation-induced parotid gland injury and to identify potential imaging biomarkers for radiation-induced xerostomia (dry mouth)-the most common and debilitating side effect after head-and-neck radiotherapy (RT).
  
  
  METHODS
  Thirty-four patients, who have developed xerostomia after RT for head-and-neck cancer, were enrolled. Radiation-induced xerostomia was defined by the Radiation Therapy Oncology Group/European Organization for Research and Treatment of Cancer morbidity scale. Ultrasound scans were performed on each patient's parotids bilaterally. The 34 patients were stratified into the acute-toxicity groups (16 patients, ≤ 3 months after treatment) and the late-toxicity group (18 patients, > 3 months after treatment). A separate control group of 13 healthy volunteers underwent similar ultrasound scans of their parotid glands. Six sonographic features were derived from the echo-intensity histograms to assess acute and late toxicity of the parotid glands. The quantitative assessments were compared to a radiologist's clinical evaluations. The diagnostic accuracy of these ultrasonic histogram features was evaluated with the receiver operating characteristic (ROC) curve.
  
  
  RESULTS
  With an area under the ROC curve greater than 0.90, several histogram features demonstrated excellent diagnostic accuracy for evaluation of acute and late toxicity of parotid glands. Significant differences (P < .05) in all six sonographic features were demonstrated between the control, acute-toxicity, and late-toxicity groups. However, subjective radiologic evaluation cannot distinguish between acute and late toxicity of parotid glands.
  
  
  CONCLUSIONS
  We demonstrated that ultrasound histogram features could be used to measure acute and late toxicity of the parotid glands after head-and-neck cancer RT, which may be developed into a low-cost imaging method for xerostomia monitoring and assessment.
authors.affiliation: Department of Radiation Oncology, Emory University, 1365 Clifton Rd NE, Atlanta, GA 30322.
authors.forename: Xiaofeng
authors.initials: X
authors.lastname: Yang
authors.affiliation: Department of Radiology and Imaging Sciences, Emory University School of Medicine, Atlanta, Georgia; Winship Cancer Institute, Emory University, Atlanta, Georgia.
authors.forename: Srini
authors.initials: S
authors.lastname: Tridandapani
authors.affiliation: Department of Radiation Oncology, Emory University, 1365 Clifton Rd NE, Atlanta, GA 30322; Winship Cancer Institute, Emory University, Atlanta, Georgia.
authors.forename: Jonathan J
authors.initials: JJ
authors.lastname: Beitler
authors.affiliation: Department of Radiation Oncology, Emory University, 1365 Clifton Rd NE, Atlanta, GA 30322; Winship Cancer Institute, Emory University, Atlanta, Georgia.
authors.forename: David S
authors.initials: DS
authors.lastname: Yu
authors.affiliation: Winship Cancer Institute, Emory University, Atlanta, Georgia; Department of Biostatistics and Bioinformatics, Rollins School of Public Health, Emory University, Atlanta, Georgia.
authors.forename: Zhengjia
authors.initials: Z
authors.lastname: Chen
authors.affiliation: Winship Cancer Institute, Emory University, Atlanta, Georgia.
authors.forename: Sungjin
authors.initials: S
authors.lastname: Kim
authors.affiliation: Winship Cancer Institute, Emory University, Atlanta, Georgia; School of Nursing, Emory University, Atlanta, Georgia.
authors.forename: Deborah W
authors.initials: DW
authors.lastname: Bruner
authors.affiliation: Department of Radiation Oncology, Emory University, 1365 Clifton Rd NE, Atlanta, GA 30322; Winship Cancer Institute, Emory University, Atlanta, Georgia.
authors.forename: Walter J
authors.initials: WJ
authors.lastname: Curran
authors.affiliation: Department of Radiation Oncology, Emory University, 1365 Clifton Rd NE, Atlanta, GA 30322; Winship Cancer Institute, Emory University, Atlanta, Georgia. Electronic address: tliu34@emory.edu.
authors.forename: Tian
authors.initials: T
authors.lastname: Liu
mesh_terms: D003627:Data Interpretation, Statistical; D005260:Female; D006258:Head and Neck Neoplasms / Q000150:complications / Q000000981:diagnostic imaging* / Q000532:radiotherapy*; D006801:Humans; D007090:Image Interpretation, Computer-Assisted / Q000379:methods; D008297:Male; D008875:Middle Aged; D010306:Parotid Gland / Q000000981:diagnostic imaging / Q000528:radiation effects; D011832:Radiation Injuries / Q000000981:diagnostic imaging* / Q000209:etiology; D020266:Radiotherapy, Conformal / Q000009:adverse effects*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D014463:Ultrasonography / Q000379:methods*; D014987:Xerostomia / Q000000981:diagnostic imaging* / Q000209:etiology*
keywords: Xerostomia; parotid gland; radiation toxicity; sonographic features; ultrasound
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