The World Federation for Ultrasound in Medicine and Biology (WFUMB) recently published three Guidelines and Recommendations for Clinical Use of Ultrasound Elastography that encompass basic principles, breast imaging, and liver imaging.
Changes in tissue stiffness are symptomatic of such diseases as cancerous masses, fibrosis associated with liver cirrhosis, and atheroma and calcification associated with arteriosclerosis. Ultrasound elastography systems enable objective assessment of tissue stiffness and the elastic properties of soft tissues, such as elasticity and viscosity. With ultrasound elastography, the extent of lesions and their degree of progression can be analyzed, as well as assessment of responses to treatments such as ablation, chemotherapy and radiofrequency. Also, because qualitative changes may be identified when morphological changes are not apparent, ultrasound elastography may be used in early detection and differential diagnosis of diseases.
Benefits of this type of imaging include the facts that it is non-invasive, is easy to use, and can be performed in real-time. The Part 1 guideline describes the basic principles, fundamental physics, and terminology associated with ultrasound elastography.
Part 2 guidelines assess all the clinically used applications of all forms of elastography used in breast imaging. The guidelines include a description of techniques and practical advice on how to perform and interpret breast elastography for optimal results. The relationship between strain and shear wave techniques are explained, and the clinical utility of some artifacts is also discussed. The authors of the guidelines emphasize that elastography is a complimentary technique to B-mode imaging that should be used to characterize an abnormality identified on conventional B-mode imaging. It should not be used when a lesion is very superficial, less than three millimeters from the skin surface. Additionally, strain elastography should not be used if a lesion is larger than in the field of view (FOV) box.
Part 3 guidelines focus on the use of elastography techniques in liver disease. It can be used to assess liver stiffness noninvasively. It measures tissue behavior when a mechanical stress is applied using ultrasound or MRI. It is very useful for follow-up of patients with chronic liver diseases.
The authors of this guideline emphasize that elastography results should be “interpreted in the full clinical context of the patient, taking into account the method used to obtain the results.” They point out that when elastography results are consistent with other clinical findings, liver biopsy may be avoided.
The guidelines are published online in Ultrasound in Medicine and Biology, available by subscription.
WFUMB issues new guidelines for ultrasound elastography. Appl Radiol.