title: Ex vivo and in vivo assessment of the non-linearity of elasticity properties of breast tissues for quantitative strain elastography.
abstract: The aim of this study was to reveal the background to the image variations in strain elastography (strain imaging [SI]) depending on the manner of manipulation (compression magnitude) during elasticity image (EI) acquisition. Thirty patients with 33 breast lesions who had undergone surgery followed by SI assessment in vivo were analyzed. An analytical approach to tissue elasticity based on the stress-elastic modulus (Young's modulus) relationship was adopted. Young's moduli were directly measured ex vivo in surgical specimens ranging from 2.60 kPa (fat) to 16.08 kPa (invasive carcinoma) under the weak-stress condition (<0.2-0.4 kPa, which corresponds to the appropriate "light touch" technique in SI investigation. The contrast (ratio) of lesion to fat in elasticity ex vivo gradually decreased as the stress applied increased (around 1.0 kPa) on the background of significant non-linearity of the breast tissue. Our results indicate that the differences in non-linearity in elasticity between the different tissues within the breast under minimal stress conditions are closely related to the variation in EI quality. The significance of the "pre-load compression" concept in tissue elasticity evaluation is recognized. Non-linearity of elasticity is an essential attribute of living subjects and could provide useful information having a considerable impact on clinical diagnosis in quantitative ultrasound elastography.
authors.affiliation: Department of Senology, Tsukuba Medical Center Foundation, Tsukuba, Ibaraki, Japan; Breast and Endocrine Surgery, Faculty of Medicine, University of Tsukuba, Tsukuba, Ibaraki, Japan. Electronic address: umemoto@tmch.or.jp.
authors.forename: Takeshi
authors.initials: T
authors.lastname: Umemoto
authors.affiliation: Department of Senology, Tsukuba Medical Center Foundation, Tsukuba, Ibaraki, Japan; Breast and Endocrine Surgery, Faculty of Medicine, University of Tsukuba, Tsukuba, Ibaraki, Japan.
authors.forename: Ei
authors.initials: E
authors.lastname: Ueno
authors.affiliation: Medical Systems Engineering Division 2, Hitachi Aloka Medical Ltd., Tokyo, Japan.
authors.forename: Takeshi
authors.initials: T
authors.lastname: Matsumura
authors.affiliation: Advanced Biomedical Engineering Research Unit, Kyoto University, Kyoto, Japan.
authors.forename: Makoto
authors.initials: M
authors.lastname: Yamakawa
authors.affiliation: Breast and Endocrine Surgery, Faculty of Medicine, University of Tsukuba, Tsukuba, Ibaraki, Japan.
authors.forename: Hiroko
authors.initials: H
authors.lastname: Bando
authors.affiliation: Medical Systems Engineering Division 2, Hitachi Aloka Medical Ltd., Tokyo, Japan.
authors.forename: Tsuyoshi
authors.initials: T
authors.lastname: Mitake
authors.affiliation: Graduate School of Medicine, Kyoto University, Kyoto, Japan.
authors.forename: Tsuyoshi
authors.initials: T
authors.lastname: Shiina
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001940:Breast / Q000601:surgery; D001943:Breast Neoplasms / Q000000981:diagnostic imaging* / Q000601:surgery*; D018567:Breast Neoplasms, Male / Q000000981:diagnostic imaging / Q000601:surgery; D055119:Elastic Modulus / Q000502:physiology*; D054459:Elasticity Imaging Techniques / Q000379:methods*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D015203:Reproducibility of Results; D016217:Ultrasonography, Mammary / Q000379:methods*
keywords: Breast cancer; Elastic modulus (Young's modulus); Elasticity imaging; Elastography; Non-linearity; Pre-load compression; Shear wave imaging; Strain; Strain imaging; Stress