Reliability of quantitative ultrasonic assessment of normal-tissue toxicity in breast cancer radiotherapy

• Type of Material: Article
• Authors: Emi J. Yoshida, Emory University; Hao Chen, Emory University; Mylin Torres, Emory University; Fundagul Andic, Emory University; Hao-Yang Liu, Emory University; Zhengjia Chen, Emory University; Xiaoyan Sun, Emory University; Walter J Curran, Emory University; Tian Liu, Emory University
• Language: English
• Date: 2012-02-01
• Publisher: Elsevier
• Publication Version: Author Accepted Manuscript (After Peer Review)
• Copyright Statement: © 2011 Elsevier Inc. All rights reserved.
• License: Creative Commons Attribution-NonCommerical-NoDerivs 3.0 Unported
• Final Published Version (URL): http://dx.doi.org/10.1016/j.ijrobp.2010.12.066
• Title of Journal or Parent Work: International Journal of Radiation Oncology - Biology - Physics
• ISSN: 0360-3016
• Volume: 82
• Issue: 2
• Start Page: 724
• End Page: 731
• Grant/Funding Information: This research was supported in part by National Cancer Institute Grant CA114313, Columbia University Women at Risk, Sindab pilot award and Susan Komen for the Cure foundation.
• Keywords: breast cancer; radiation toxicity; ultrasound; tissue characterization
• Research Categories: Health Sciences, Oncology; Health Sciences, Medicine and Surgery; Biology, Biostatistics

Abstract

Purpose 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. Method and Materials Our ultrasound technique analyzes radio-frequency 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 semi-automatic 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 post radiotherapy) and those of 18 patients were evaluated for late toxicity (≥6 months post radiotherapy). All patients were treated according to a standard radiotherapy protocol. To assess intra-observer reliability, one observer analyzed 720 images in UBTAT and then repeated the analysis 3 months later. To assess inter-observer 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 inter-observer reliability. Ultrasound assessment and clinical evaluation were also compared. Results Intra-observer ICC was 0.89 for dermal toxicity, 0.74 for hypodermal toxicity, and 0.96 for glandular-tissue toxicity. Inter-observer 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 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. Conclusion Early and late radiation-induced effects on normal tissue can be reliably assessed using quantitative ultrasound.