(E)US elastography: Current status and perspectives

(Endo)sonographic real-time elastography is a new method to describe the mechanical properties of tissue. Similar to colour flow Doppler ultrasonography, a region of interest is defined. The relative stiffness of the tissues within this area is described by colours superimposing on the B-mode image. Real-time elastography can be performed with linear scanners for transcutaneous use, rigid endocavitary probes and with flexible echoendoscopes. The probes can be used to compress the tissue. The elasticity modulus is calculated from the resulting deformation of the tissue. in endoscopic ultrasound, arterial and cardiac pulsations or respiratory movements cause the deformation of the tissue that is used for the calculation. Several studies have demonstrated that real-time elastography is feasible and improves the diagnostic accuracy for tumours of the breast, the prostate, the cervix, and the thyroid gland. Endosonographic elastography has been employed in the examination of lymph nodes and the pancreas. For the differentiation between benign and malignant lymph nodes, the accuracy is reported to be 85% to 90%. Therefore, the method seems to be useful to select lymph nodes suitable for biopsy. The elastographic pattern of malignant tumours of the pancreas is different from that of the normal pancreas, but similar to that of chronic pancreatitis due to the same biomechanical architecture. Therefore, the early diagnosis of cancer within chronic pancreatitis will probably not be improved by elastography. In summary, (endo)sonographic real-time elastography is a promising new method. Nevertheless, prospective studies are needed to define useful applications and the clinical significance of the method.