Editorial from Editor-in-Chief

During the last decade, numerous methods and devices have been developed implementing elastography or mechanical imaging in various medical applications such as the differentiation of benign and malignant lesions in the liver, breast and prostate as well as the characterization of vaginal wall elasticity. Elastography is a noninvasive method in which stiffness or strain of soft tissue are used to detect or classify tumors. Mechanical imaging is a tactile or stress imaging based on the visualization of tissue internal structures in terms of their elasticity modulus. A tumor or a suspicious cancerous growth is normally 5-28 times stiffer than the background of normal tissue. When a mechanical compression or vibration is applied, the tumor deforms less than the surrounding tissue. The strain in the tumor is less than the surrounding tissue. Elastography has been shown to be affected by the degree of adherence of the tumor to its surroundings, indicating a potential to extend its method to tumor mobility characterization to improve diagnostic accuracy and surgical guidance. Ultrasonic imaging is the most common medical imaging technique producing elastograms, and it has the advantages of being cheaper, faster and more portable than other technique. Magnetic resonance elastogram combines MRI with sound waves to create a visual map, showing the elasticity of body tissue, and is used primarily to detect hardening of the liver. This issue present updated informations about the techniques and clinical applications of new emerging technology by world experts. Aglyamov et al. discuss the applications of elasticity imaging and sensing using targeted motion using laser-induced gas microbubbles as well as magnetic nanoparticles, and also report their recent experimental results. Konofagou et al. review the applications of harmonic motion imaging for tumor detection as well as its relevance in thermal treatment. Urban et al. provide an overview of viscoelasticity and development as well as application of shear wave velocity dispersion ultrasound vibrometry. Hansen et al. describe the basics, background and results of ultrasound strain imaging using cross-correlation. Litwiller et al. summarize the fundamental techniques and applications of magnetic resonance elastography, especially for the staging of hepatic cirrhosis. Sinkus et al. focus on the dynamic 3D approach via MRI and report on a large patient collective that mechanical parameters are very pertinent for the differentiation between low-grade and mid/high-grade hepatic fibrosis. Finally Sarvazyan and Artann laboratories review the biomechanical basis of mechanical imaging and its applications of evaluating breast cancer, prostate lesions and vaginal wall elasticity.