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Percutaneous and endoscopic ultrasound are very useful complementary imaging tools in the detailed assessment of physiological as well as pathological lymph nodes in almost all anatomical regions of the human body. A comprehensive consideration of various features obtained by gray-scale and color Doppler sonography is the basis of the differentiation of benign from malignant lymphadenopathy. Sonographic elastography and contrast-enhanced sonography may provide further information. Nevertheless the sonographic differential diagnosis of enlarged and structurally altered lymph nodes has some limitations. (Endoscopic) ultrasound guided biopsy permits histological diagnosis of pathological lymph nodes with minimal risk, low cost, and high diagnostic accuracy. The sonographical evaluation of lymph nodes is an essential adjunct to the clinical investigation in staging of malignant tumors and lymphoma, in the case of palpable lymph nodes, and in various benign diseases. [ABSTRACT FROM AUTHOR]

Incidentally detected focal liver lesions are commonly encountered in clinical practice presenting a challenge in the daily department work flow. Guidelines for the management of incidental focal liver lesions have been published but comments, illustrations and recommendations regarding practical issues are crucial. The unique features of contrast-enhanced ultrasound in non-invasive assessment of focal liver lesion enhancement throughout the vascular phases in real-time has allowed an impressive improvement in the diagnostic accuracy of ultrasound. We highlight the additional benefit of contrast-enhanced ultrasound over conventional B-mode ultrasound imaging in detection, characterization, differential and final diagnosis of focal liver lesions, as well as for liver metastases screening. The current roles of cross-sectional imaging are explained in detail, with indications and limitations for each procedure. The advantages of CEUS, such as non-ionizing radiation exposure, cost benefits, non-iodinate contrast agents, and repeatability are also described ultimately improving patient management. [ABSTRACT FROM AUTHOR]

Abstract: Real-time elastography (RTE) performed during endoscopic ultrasound (EUS) is a relatively new technique which allows the evaluation of tissue stiffness, with the intent of better characterising lesions during EUS examinations. The aim of this comprehensive review was to describe the technique of RTE-EUS, as well as the clinical applications, including the study of pancreatic lesions, but also hepatobiliary, gastrointestinal (GI) tract pathology (including anal canal), lymph nodes, adrenal glands, lung and mediastinum, as well as urogenital applications. One of the advantages of the RTE-EUS technique is especially the possibility to be used in various locations accessible from the GI tract. Future developments are also briefly discussed, as elastography is a tissue characterising technique that will certainly not replace biopsy, but will rather be an adjunct during EUS examinations, due to its ease of use and low cost. [Copyright &y& Elsevier]

The vortex shedding in the wake behind linearly tapered circular cylinders has been considered for the two taper ratios 75:1 and 100:1. The Reynolds number based on the velocity of the incoming flow and the largest diameter was in the range from 130 to 180. The low Reynolds number assured that laminar flow prevailed in the entire flow field. The full unsteady three-dimensional Navier–Stokes equations were solved numerically with the view of exploring the rather complex vortex shedding phenomena caused by the variation of the natural shedding frequency along the span of the cylinder. The accurate computer simulations showed that this variation gave rise to discrete shedding cells, each with its own characteristic frequency and inclined with respect to the axis of the cylinder. Flow visualizations revealed that vortex dislocation and splitting took place in the numerically simulated flow fields. The computer simulations compared surprisingly well with the extensive laboratory experiments reported by Piccirillo & Van Atta in 1993 for a range of comparable conditions; this has enabled detailed analyses of other flow variables (notably pressure and vorticity) than those readily accessible in a physical experiment. However, distinct differences in the vortex dynamics are observed in some of the cases. [Copyright &y& Elsevier]

A computerized flow analysis of wake phenomena caused by a discontinuity in cylinder diameter is presented. The vortex linkage and half-loop formation observed experimentally by Lewis and Gharib [Phys. Fluids A 4, 104 (1992)] have for the first time been reproduced numerically. The instantaneous vorticity and pressure fields provide a distinct picture of the direct-mode interaction, from which it is concluded that a new half-loop is formed every third shedding cycle. [ABSTRACT FROM AUTHOR]