journal homepage: www.elsevier.com/locate/jmbbm Available online at www.sciencedirect.com Research Paper Application of digital image cross-correlation and smoothing function to the diagnosis of breast cancer Yougun Han, Dong-Woo Kim, Hyock-Ju Kwon n Department of Mechanical and Mechatronics Engineering, University of Waterloo, 200 University Ave. W., Waterloo, ON, Canada N2L 3G1 article info Article history: Received 25 February 2012 Received in revised form 7 May 2012 Accepted 8 May 2012 Available online 23 May 2012 Keywords: Elastogram DIC DVC Smoothing function abstract Digital image correlation (DIC) algorithm was applied to 2D and 3D B-mode ultrasound (US) images to create 2D and 3D elastograms based on displacement-gradient. The roughness of elastograms caused by signal noises and sub-pixel errors could be greatly improved by employing the smoothing function based on the penalized least square regression method. Using the smoothed elastogram, the size and the relative modulus of the inclusion could be estimated with a reasonable accuracy. The study suggests that the 2D and 3D displacement-gradient elastograms acquired by the combination of DIC and smoothing function have the potential to diagnose pathological tissues in-vivo, and to provide new information that is related to tissue structure and/or pathology. & 2012 Elsevier Ltd. All rights reserved. 1. Introduction Cancer is the top leading cause of death in North America (Jemal et al., 2011; Milan, 2011). Among the various cancers, breast cancer is the most common malignancy in women and the second most common cause of cancer-related mortality (Jemal et al., 2011). In the past several years, early detection and treatment of breast carcinoma has received increased attention and has contributed significantly to the decrease of mortality rate (Smith et al., 2003). Currently, mammography, ultrasound (US) imaging and MRI (magnetic resonance ima- ging) are all used in congruence with each other for non- invasive diagnosis of breast cancer. Although each has its own effective purpose, no single screening method or combi- nation stands out for every individual female. Among them, mammography has been commonly used for the early detection of breast cancer (Lee et al., 2010a). However, regardless of its contribution to the early detection and the reduction of mortality, high false positive rate causing addi- tional testing or biopsy, and the possibility of overdiagnosis and overtreatment arguably outweigh the benefits (Skrabanek, 1989). It is also known that mammography is not effective for Asian women having small, dense breasts (Zhi et al., 2007). On the other hand, the addition of MRI to the screening algorithm adds considerable cost of over $50,000 per cancer (Lee et al., 2010b). US imaging is relatively affordable and accessible; thus it has been given interests as a modality to supplement or replace mammography, especially for the women with dense breasts (Zhi et al., 2007). However, in many cases, the pathologic lesion may not possess sufficient echographic properties and therefore it is difficult to detect the lesion by only using B-mode US images. The breast comprises a complex group of tissues, including fat, glandular, and fibrous tissues, each of which has different stiffness. Pathological changes, such as carcinoma in situ (CIS) and invasive carcinoma, are also known to affect the 1751-6161/$ - see front matter & 2012 Elsevier Ltd. All rights reserved. http://dx.doi.org/10.1016/j.jmbbm.2012.05.007 n Corresponding author. Tel.: þ1 519 888 4567x33427; fax: þ1 519 885 5862. E-mail addresses: y24han@uwaterloo.ca (Y. Han), kdw525@gmail.com (D.-W. Kim), hjkwon@uwaterloo.ca (H.-J. Kwon). journal ofthe mechanical behavior of biomedical materials 14 (2012)7–18