title: Quantitative Ultrasonic Nakagami Imaging of Neck Fibrosis After Head and Neck Radiation Therapy.
abstract: OBJECTIVE
  To investigate the feasibility of ultrasound Nakagami imaging to quantitatively assess radiation-induced neck fibrosis, a common sequela of radiation therapy (RT) to the head and neck.
  
  
  METHODS
  In a pilot study, 40 study participants were enrolled and classified into 3 subgroups: (1) a control group of 12 healthy volunteers; (2) an asymptomatic group of 11 patients who had received intensity modulated RT for head and neck cancer and had experienced no neck fibrosis; and (3) a symptomatic group of 17 post-RT patients with neck fibrosis. Each study participant underwent 1 ultrasound study in which scans were performed in the longitudinal orientation of the bilateral neck. Three Nakagami parameters were calculated to quantify radiation-induced tissue injury: Nakagami probability distribution function, shape, and scaling parameters. Physician-based assessments of the neck fibrosis were performed according to the Radiation Therapy Oncology Group late morbidity scoring scheme, and patient-based fibrosis assessments were rated based on symptoms such as pain and stiffness.
  
  
  RESULTS
  Major discrepancies existed between physician-based and patient-based assessments of radiation-induced fibrosis. Significant differences in all Nakagami parameters were observed between the control group and 2 post-RT groups. Moreover, significant differences in Nakagami shape and scaling parameters were observed among asymptomatic and symptomatic groups. Compared with the control group, the average Nakagami shape parameter value increased by 32.1% (P<.001), and the average Nakagami scaling parameter increased by 55.7% (P<.001) for the asymptomatic group, whereas the Nakagami shape parameter increased by 74.1% (P<.001) and the Nakagami scaling parameter increased by 83.5% (P<.001) for the symptomatic group.
  
  
  CONCLUSIONS
  Ultrasonic Nakagami imaging is a potential quantitative tool to characterize radiation-induced asymptomatic and symptomatic neck fibrosis.
authors: Department of Radiation Oncology and Winship Cancer Institute, Emory University, Atlanta, Georgia.
authors: Xiaofeng
authors: X
authors: Yang
authors: Department of Radiation Oncology, Cedars-Sinai Medical Center, Los Angeles, California.
authors: Emi
authors: E
authors: Yoshida
authors: Department of Radiation Oncology and Winship Cancer Institute, Emory University, Atlanta, Georgia.
authors: Richard J
authors: RJ
authors: Cassidy
authors: Department of Radiation Oncology and Winship Cancer Institute, Emory University, Atlanta, Georgia.
authors: Jonathan J
authors: JJ
authors: Beitler
authors: Department of Radiation Oncology and Winship Cancer Institute, Emory University, Atlanta, Georgia.
authors: David S
authors: DS
authors: Yu
authors: Department of Radiation Oncology and Winship Cancer Institute, Emory University, Atlanta, Georgia.
authors: Walter J
authors: WJ
authors: Curran
authors: Department of Radiation Oncology and Winship Cancer Institute, Emory University, Atlanta, Georgia. Electronic address: tliu34@emory.edu.
authors: Tian
authors: T
authors: Liu
mesh_terms: D000230:Adenocarcinoma / Q000188:drug therapy / Q000532:radiotherapy; D000328:Adult; D002294:Carcinoma, Squamous Cell / Q000188:drug therapy / Q000532:radiotherapy; D003430:Cross-Sectional Studies; D005240:Feasibility Studies; D005260:Female; D005355:Fibrosis; D006258:Head and Neck Neoplasms / Q000188:drug therapy / Q000532:radiotherapy* / Q000601:surgery; D006801:Humans; D060828:Induction Chemotherapy / Q000379:methods; D008297:Male; D008875:Middle Aged; D009333:Neck / Q000000981:diagnostic imaging* / Q000473:pathology / Q000528:radiation effects; D037981:Neck Dissection; D009336:Necrosis; D010865:Pilot Projects; D050397:Radiotherapy, Intensity-Modulated / Q000009:adverse effects*; D014463:Ultrasonography / Q000379:methods