title: Axial-shear strain distributions in an elliptical inclusion model: experimental validation and in vivo examples with implications to breast tumor classification.
abstract: Recently, we reported on the axial-shear strain fill-in of the interior of loosely bonded stiff elliptical inclusions in a soft background at non-normal orientations, and the lack of fill-in in firmly bonded inclusions at any orientation. In this paper, we report on the experimental validation of the simulation studies using tissue-mimicking gelatin-based phantoms. We also show a few confirmatory examples of the existence of these phenomena in benign vs. malignant breast lesions in vivo. Phantom experiments showed that axial-shear strain zones caused by firmly bonded elliptical inclusions occurred only outside of the inclusion, as predicted by the simulation. By contrast, the axial-shear strain zones filled in the interior of loosely bonded elliptical inclusions at non-normal orientations. The axial-shear strain elastograms obtained from the in vivo cases appeared to be in general agreement with our experimental results. The results reported in this paper may have important clinical implications. Specifically, axial-shear strain fill-in inside an inclusion may be a unique signature of stiff, loosely bonded, ellipsoidal or elongated inclusions at non-normal orientations. Thus, it may be useful as a marker of benignity of benign breast lesions (e.g., fibroadenomas) that are generally stiff, elongated and loosely bonded to the host tissues.
authors.affiliation: The University of Texas Medical School, Department of Diagnostic and Interventional Imaging, Houston, TX 77030, USA.
authors.forename: Arun K
authors.initials: AK
authors.lastname: Thittai
authors.forename: Belfor
authors.initials: B
authors.lastname: Galaz
authors.forename: Jonathan
authors.initials: J
authors.lastname: Ophir
mesh_terms: D000465:Algorithms; D016880:Anisotropy; D001943:Breast Neoplasms / Q000000981:diagnostic imaging* / Q000503:physiopathology*; D003198:Computer Simulation; D055119:Elastic Modulus; D054459:Elasticity Imaging Techniques / Q000295:instrumentation / Q000379:methods*; D005260:Female; D018226:Fibroadenoma / Q000000981:diagnostic imaging* / Q000503:physiopathology*; D006801:Humans; D007089:Image Enhancement / Q000379:methods; D007090:Image Interpretation, Computer-Assisted / Q000379:methods*; D008327:Mammography / Q000295:instrumentation / Q000379:methods*; D008954:Models, Biological; D019047:Phantoms, Imaging; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D033081:Shear Strength