New advances in elastography from “The Technology Partnership” could lead to improvements in surgical procedures and enhance a doctor’s ability to navigate around the body during operations.
Elastography is a medical imaging technique that maps the elastic properties of soft tissue to provide diagnostic information during surgery. The process determines the stiffness of tissue and can be adapted to measure the level of muscle contraction. Cancerous cells, for example, will often be profoundly stiffer than the surrounding tissue and diseased livers are stiffer than healthy ones.
Elastography’s strength lies in its ability to image tissues and organs that ultrasound cannot reach. It also has the advantage of being more uniform across operators and less dependent on operator skill than most methods of ultrasound elastography.
Other types of Elastography include:
Transient elastography, however, “gives a quantitative one-dimensional (i.e. a line) image of tissue stiffness. It functions by vibrating the skin with a motor to create a passing distortion in the tissue (ashear wave), and imaging the motion of that distortion as it passes deeper into the body using a 1D ultrasound beam. It then displays a quantitative line of tissue stiffness data (the Young’s modulus). This technique is used mainly by the FibroScan system, which is used for liver assessment, for example, to diagnose cirrhosis.”
In Acoustic Radiation Force Impulse Imaging (ARFI) uses ultrasound to create a 2-D map of tissue stiffness. It creates a push inside the tissue using the acoustic radiation force from a focused ultrasound beam. By pushing into the tissue masses, a map of varying tissue densities is created.
Whereas Supersonic Shear Imaging gives a quantitative, real-time two-dimensional map of tissue stiffness. It is often called ‘Shear Wave Elastography’, though it is not the only method to use shear waves. Like ARFI and SWEI, supersonic shear imaging uses acoustic radiation force to induce a ‘push’ inside the tissue of interest, and like SWEI, the tissue’s stiffness is computed from how fast the resulting shear wave travels through the tissue. By using many near-simultaneous pushes, and by using an advanced ultrafast imaging technique to track the wave, supersonic shear imaging can make a two-dimensional quantitative map of the tissue’s stiffness (the Young’s modulus), and create one every second.
It has demonstrated clinical benefit in breast, thyroid, liver, prostate and musculoskeletal imaging. Ultrasound Elasticity Imaging is used for breast examination with a number of high-resolution linear transducers. A large multi-center breast imaging study has demonstrated both reproducibility and significant improvement in the classification of breast lesions when shear wave elastography images are added to the interpretation of standard B-mode and Color mode ultrasound images.