Tumor characterization by ultrasound elastography and contrast-enhanced ultrasound

Abstract

State-of-the-art techniques of ultrasound elastography can contribute to the characterization of focal breast lesions and detection of malignant tumors in various organs. Another area of current interest is the differentiation of focal liver lesions in terms of vascularization patterns measured by perfusion ultrasound. This chapter provides an overview of the different techniques and their diagnostic role in clinical routine based on a review of the current literature. The most important techniques are compression or vibration elastography, shear wave elastography (SWE), and contrast-enhanced ultrasound (CEUS). Currently available scientific evidence suggests that elastography provides important supplementary information for the differentiation of breast lesions under routine clinical conditions. The information is immediately available and improves specificity. Strain ratio (SR) is especially useful in women with a high pretest likelihood of breast cancer. Prostate cancer also shows characteristic differences in terms of elastographic properties compared with surrounding tissue. Here, elastography can improve targeted biopsy for the workup of suspicious focal lesions and is superior to routine prostate biopsy guided by B-mode ultrasound. CEUS has high diagnostic accuracy and is comparable to computed tomography (CT) and magnetic resonance imaging (MRI) in terms of tumor characterization. Having a low rate of adverse effects, CEUS can be used in patients with impaired renal function or contraindications to CT or MRI contrast agents. Quantifiable elastography and CEUS have recently started to expand the role of classic B-mode ultrasound in oncology. Quantification of tumor stiffness and perfusion can improve the differential diagnosis. These two ultrasound techniques are beginning to enter the clinic and offer a fascinating potential for further advances including improved standardization of ultrasound diagnosis.