The aim of the paper is to provide a comprehensive overview on the applications of real time sonoelastography (SE) in the diagnosis of superficial lymphadenopathy. Some technical aspects of performing SE are presented as a preamble. The typical appearance of benign and malignant nodes is illustrated. The paper discusses and depicts the various elastographic scores in use. It also provides a critical appraisal of the relative strain ratio (SR) or stiffness index. Shear wave elastography, as a novel technique, is mentioned. In conclusion, hardness on more than 50% of the node surface or SR > 1.5 is fair to good indicators of malignancy. Work is still needed both to fully understand the various appearance of disease and to standardize the application.Keywords: sonoelastography, lymph nodes, neoplasm Accurate assessment of the superficial lymph node status is of paramount importance in the treatment planning, follow-up and prognosis of malignancies originating in the head and neck, breast, superficial tissues or in lymphoma. Ultrasonography (US) is extensively used as a first line diagnostic means, due to its cost-effectiveness, ease of use and high resolution of provided information. However, grey-scale and Doppler information are limited either in sensitivity or specificity and no single US criterion has sufficient diagnostic accuracy [1][2][3][4][5].Sonoelastography (SE) depicts the relative stiffness of tissues. Beyond breast, prostate and thyroid applications, over the last five years, the method was also used as a complimentary imaging technique to conventional US for the assessment of superficial lymph nodes [6][7][8][9]. Assessment of nodal SE information is done either by grading the appearance on a score system (elasticity score -ES) or by calculating a relative stiffness or strain ration (SR) [10].The aim of this paper is to review the current status of the knowledge on the applications of SE in the diagnosis of the character of superficial lymphadenopathy.
Technical aspectsReal-time sonoelastography is, essentially, an elaborate speckle tracking technique with autocorrelation for out-of-plane displacement of the target [11,12]. It provides information about the relative stiffness of the structures within the scan plane, inside a region of interest (ROI). It is, therefore, important to encompass in the scan area not only the target lesion but also surrounding "normal" reference soft tissues. There are no standard recommendations on how to achieve this. In our experience [13,14], the upper limit of the ROI should always be placed as close to the transducer as possible. When aiming to use ES, the ROI should exceed the target boundaries at least 5 mm on each side. When the purpose is to calculate SR, the ROI should be as wide as possible, to encompass both the target lesion and the surrounding, reference tissue, at the same depth with the lesion. Transducer stabilizer, although desirable, is difficult to use of curved surfaces such as neck or axilla. During compression the transducer should be perpen...
