Vibrational soft tissue

S. Catheline, J. L. Thomas, F. Wu and M. Fink, Diffraction field of a low-frequency vibrator in soft tissues using transient elastography, IEEE Trans. Ultrason. Ferroelect. Freq. Contr., 1999, 46, 1013-1020. 

Preparation of Soft Tissue for Vibrational Spectroscopic Imaging... 

The vibrational spectra of reference materials, notably the main components of soft tissue, are introduced in figure 3.1. In the IR spectrum (trace A) of the all-beta... 

Colon tissue was selected as a model for the comparative analysis of soft tissue by FT-IR and Raman imaging at low and high lateral resolution, because it contains aU four major tissue types such as muscle, connective tissue, epithelium and also nerve cells. The vibrational spectroscopic fingerprints of normal tissues and their distribution in control samples were determined. The compilation of such data is important before a method can be applied to pathological colon tissue such as colorectal adenocarcinoma, which is the third most common form of cancer and the second leading cause of death among cancer patients in the Western world. Colorectal adenocarcinomas originate from epithelial cells and are able to infiltrate the subjacent layers of colon and rectum. 

Although in its early stages, one can be optimistic that vibrational spectroscopic imaging has the potential to become fully accepted as a diagnostic tool for soft tissues, with sufficient sensitivity and specificity for rapid and nondestructive in vitro, ex vivo and in vivo analyses. 

A risk factor is defined as an attribute or exposure that increases the probability of a disease or disorder (Putz-Anderson, 1988). Biomechanical risk factors for musculoskeletal disorders include repetitive and sustained exertions, awkward postures, and application of high mechanical forces. Vibration and cold environments may also accelerate the development of musculoskeletal disorders. Typical tools that can be used to identify the potential for development of musculoskeletal disorders include conducting work-methods analyses and checklists designed to itemize undesirable work site conditions or worker activities that contribute to injury. Since most of manual work requires the active use of the arms and hands, the structures of the upper extremities are particularly vulnerable to soft tissue injury. WUEDs are typically associated with repetitive manual tasks with forceful exertions, such as those performed at assembly lines, or when using hand tools, computer keyboards and other devices, or operating machinery. These tasks impose repeated stresses to the upper body, that is, the muscles, tendons, ligaments, nerve tissues, and neurovascular structures. There are three basic types of WRDs to the upper extremity tendon disorder (such as tendonitis), nerve disorder (such as carpal tunnel syndrome), and neurovascular disorder (such as thoracic outlet syndrome or vibration-Raynaud s syndrome). The main biomechanical risk factors of musculoskeletal disorders are presented in Table 22. 

The complexity of a living organism, and its ability to modify its mechanical properties (e.g., in response to mechanical or physiological demands or muscle tension), necessitates the carefiil design of experiments. There is a large variability in response between individuals. Also, the direct attachment of vibration and shock sensors to soft tissues produces a mechanical load that influences tissue motion. With appropriate measurement methods and instrumentation (ISO 8041,1990), mechanical responses to vibration can be determined for tissues, body segments, and the whole body. 

Tissue Properties. The properties of human tissues when the body is considered a linear, passive mechanical system are summarized in Table 10.1 (von Gierke et al., 2002 Goldstein et al., 1993). The values shown for soft tissues are typical of muscle tissue, while those for bone depend on the structure of the specific bone. Cortical bone is the dominant constituent of the long bones (e.g., femiu, tibia), while trabecular bone, which is more elastic and energy absorbent, is the dominant constituent of the vertebrae. The shear viscosity and bulk elasticity of soft tissue are from a model for the response in vivo of a human thigh to the vibration of a small-diameter piston (von Gierke et al., 1952)... 

Transducers contain a piezo-electric crystal that vibrates when an electric current is passed through it, producing an ultrasound beam which propagates through the soft tissues. Reflection or refraction of the ultrasound beam may occur when it reaches a soft tissue interface of different acoustic impedance. The reflected ultrasound beams then return to the transducer where they are converted to electrical currents and subsequently to form an image. When there is a large difference in impedance, for example at a hone-soft tissue interface, a bright echo is produced. 

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