Ultrasonic Measurement and Imaging with Lateral Modulation – Echo, Tissue Motion and Elasticity

Abstract

It is remarkable that the pathological state of human soft tissues highly correlates with static and low-frequency mechanical properties, particularly shear elasticity (e.g., Sumi, 2005d). Accordingly, we have been developing ultrasonic (US)-strain-measurement-based onedimensional (1D) (Sumi et al., 1993, 1995a, 2010f; Sumi, 1999b, 2005d, 2008a, 2010d; Sumi & Matsuzawa, 2007b), 2D (Sumi et al., 1993, 1995a; Sumi, 1999c, 2005d, 2006b, 2007g, 2008a, 2008c, 2010d) and 3D (Sumi, 1999c, 2005d, 2006b, 2007g, 2010d) shear or Young modulus reconstruction/imaging techniques as differential diagnostic tools for deseases of various in vivo tissues, such as the breast (Sumi, 1999a, 2005b, 2005d; Sumi & Matsuzawa 2007b; Sumi et al., 1995b(strain), 1996, 1997, 1999b, 2000b) and liver (Sumi et al., 2001a, 2001b; Sumi, 2005d), i.e., cancerous deseases etc. Other soft tissues such as heart or blood vessel are also our targets, i.e., myocardinal infraction, atherosclerosis etc. After the first report of the differential type inverse problem of shear modulus by Sumi (1993, 1995a), immediately the results obtained on agar phantoms [e.g., Sumi et al., 1994a(strain & shear modulus), 1994b, 1995d], in vivo breasts (e.g., Sumi et al., 1995b, 1996, 1997; Sumi, 1999a, 1999b) and in vivo liver (e.g., Sumi et al., 2000a, 2001a, 2001b; Sumi 2005d) were reported. For such in vivo tissues, a suitable combination of simple, minimally invasive therapy techniques such as chemotherapy, cryotherapy, and thermal therapy (e.g., Sumi, 2005d; Sumi et al., 2001a) etc with our reconstruction techniques would lead to an innovative, new clinical strategy that would enable differential diagnosis followed by immediate treatment so that overall medical expenses could be substantially reduced (Sumi, 2005d). This is because our developed techniques allow non-invasive confirming of a treatment effectiveness in realtime, i.e., a degeneration. Our early reports on the interstitial rf/micro wave thermal coagulation thrapy are Sumi et al., 2000a, 2001b; Sumi, 2005d, etc. In the respective 1D, 2D and 3D techniques, a 1D (axial) displacement field, and 2D and 3D displacement vector fields generated by compression, vibration, heart motion, radiation force etc are measured to obtain 1D (axial) strain, and 2D and 3D strain tensor fields by partial differentiation. Many other researchers are also developing shear modulus reconstruction methods (e.g., Kallel & Bertrand, 1996; Plewes et al., 2000; Doyley et al., 2005) based on various displacement/strain measurement methods, e.g., conventional 1D Doppler method (Wilson & Robinson, 1982) and 1D autocorrelation method (1D AM) (Kasai et al.,