title: Reliability of quantitative ultrasonic assessment of normal-tissue toxicity in breast cancer radiotherapy.
abstract: OBJECTIVE
  We have recently reported that ultrasound imaging, together with ultrasound tissue characterization (UTC), can provide quantitative assessment of radiation-induced normal-tissue toxicity. This study's purpose is to evaluate the reliability of our quantitative ultrasound technology in assessing acute and late normal-tissue toxicity in breast cancer radiotherapy.
  
  
  METHODS
  Our ultrasound technique analyzes radiofrequency echo signals and provides quantitative measures of dermal, hypodermal, and glandular tissue toxicities. To facilitate easy clinical implementation, we further refined this technique by developing a semiautomatic ultrasound-based toxicity assessment tool (UBTAT). Seventy-two ultrasound studies of 26 patients (720 images) were analyzed. Images of 8 patients were evaluated for acute toxicity (<6 months postradiotherapy) and those of 18 patients were evaluated for late toxicity (≥ 6 months postradiotherapy). All patients were treated according to a standard radiotherapy protocol. To assess intraobserver reliability, one observer analyzed 720 images in UBTAT and then repeated the analysis 3 months later. To assess interobserver reliability, three observers (two radiation oncologists and one ultrasound expert) each analyzed 720 images in UBTAT. An intraclass correlation coefficient (ICC) was used to evaluate intra- and interobserver reliability. Ultrasound assessment and clinical evaluation were also compared.
  
  
  RESULTS
  Intraobserver ICC was 0.89 for dermal toxicity, 0.74 for hypodermal toxicity, and 0.96 for glandular tissue toxicity. Interobserver ICC was 0.78 for dermal toxicity, 0.74 for hypodermal toxicity, and 0.94 for glandular tissue toxicity. Statistical analysis found significant changes in dermal (p < 0.0001), hypodermal (p = 0.0027), and glandular tissue (p < 0.0001) assessments in the acute toxicity group. Ultrasound measurements correlated with clinical Radiation Therapy Oncology Group (RTOG) toxicity scores of patients in the late toxicity group. Patients with RTOG Grade 1 or 2 had greater ultrasound-assessed toxicity percentage changes than patients with RTOG Grade 0.
  
  
  CONCLUSIONS
  Early and late radiation-induced effects on normal tissue can be reliably assessed using quantitative ultrasound.
authors: Department of Radiation Oncology, Emory University, Atlanta, GA 30322, USA.
authors: Emi J
authors: EJ
authors: Yoshida
authors: Hao
authors: H
authors: Chen
authors: Mylin
authors: M
authors: Torres
authors: Fundagul
authors: F
authors: Andic
authors: Hao-Yang
authors: HY
authors: Liu
authors: Zhengjia
authors: Z
authors: Chen
authors: Xiaoyan
authors: X
authors: Sun
authors: Walter J
authors: WJ
authors: Curran
authors: Tian
authors: T
authors: Liu
mesh_terms: D000328:Adult; D000368:Aged; D001940:Breast / Q000528:radiation effects*; D001943:Breast Neoplasms / Q000000981:diagnostic imaging / Q000532:radiotherapy*; D020405:Dermis / Q000000981:diagnostic imaging / Q000528:radiation effects; D005260:Female; D006801:Humans; D008875:Middle Aged; D015588:Observer Variation; D011832:Radiation Injuries / Q000000981:diagnostic imaging*; D018787:Radiation Oncology; D011855:Radiodermatitis / Q000000981:diagnostic imaging; D015203:Reproducibility of Results; D012867:Skin / Q000000981:diagnostic imaging* / Q000528:radiation effects; D013997:Time Factors; D014465:Ultrasonics; D016217:Ultrasonography, Mammary / Q000379:methods