An ultrasound imaging mode called elastography has been studied for several years. It has now become available commercially. By subjecting tissues to a small push (using a push on the transducer by the sonographer, who applies a high-amplitude ultrasound pulse or makes use of natural motions such as respiration) and then tracking the movement of the tissues, it is possible to estimate and depict tissue stiffness (because soft tissues will move more than hard ones). Essentially, elastography is the imaging version of palpation. It is commonly shown as a color overlay on top of the gray-scale image, and has been used clinically for:
- Cancer detection and characterization of small parts (breast, thyroid and prostate)
- Assessing the viability of the myocardium
- Monitoring therapies that alter tissue composition, such as ablation procedures.
Adapted from Kremkau, Diagnostic Sonography: Principles and Instruments, 8th edition, 2011