Ultrasound shear wave elastography for liver disease. A critical appraisal of the many actors on the stage

In the last 12\u200a-\u200a18 months nearly all ultrasound manufacturers have arrived to implement ultrasound shear wave elastography modality in their equipment for the assessment of chronic liver disease; the few remaining players are expected to follow in 2016.When all manufacturers rush to a new technology at the same time, it is evident that the clinical demand for this information is of utmost value. Around 1990, there was similar demand for color Doppler ultrasound; high demand for contrast-enhanced ultrasonography was evident at the beginning of this century, and around 2010 demand increased for strain elastography. However, some issues regarding the new shear wave ultrasound technologies must be noted to avoid misuse of the resulting information for clinical decisions. As new articles are expected to appear in 2016 reporting the findings of the new technologies from various companies, we felt that the beginning of this year was the right time to present an appraisal of these issues. We likewise expect that in the meantime EFSUMB will release a new update of the existing guidelines 1 2.The first ultrasound elastography method became available 13 years ago in the form of transient elastography with Fibroscan(\uae) 3. It was the first technique providing non-invasive quantitive information about the stiffness of the liver and hence regarding the amount of fibrosis in chronic liver disease 3. The innovation was enormous, since a non-invasive modality was finally available to provide findings otherwise achievable only by liver biopsy. In fact, prior to ultrasound elastography, a combination of conventional and Doppler ultrasound parameters were utilized to inform the physician about the presence of cirrhosis and portal hypertension 4. However, skilled operators were required, reproducibility and diagnostic accuracy were suboptimal, and it was not possible to differentiate the pre-cirrhotic stages of fibrosis. All these limitations were substantially improved by transient elastography, performed with Fibroscan(\uae), a technology dedicated exclusively to liver elastography. Since then, more than 1300 articles dealing with transient elastography have been listed in PubMed, some describing results with more than 10,000 patients 5. The technique has been tested in nearly all liver disease etiologies, with histology as the reference standard. Meta-analysis of data, available in many etiologies 6, showed good performance and reproducibility as well as some situations limiting reliability 5. Thresholds for the different fibrosis stages (F0 to F4) have been provided by many large-scale studies utilizing histology as the reference standard 7. Transient elastography tracks the velocity of shear waves generated by the gentle hit of a piston on the skin, with the resulting compression wave traveling in the liver along its longitudinal axis. The measurement is made in a 4\u200acm long section of the liver, thus able to average slightly inhomogeneous fibrotic deposition.In 2008 a new modality became available, Acoustic Radiation Force Impulse (ARFI) quantification, and classified by EFSUMB 1 as point shear wave elastography (pSWE), since the speed of the shear wave (perpendicular to the longitudinal axis) is measured in a small region (a "point", few millimeters) at a freely-choosen depth within 8\u200acm from the skin. This technology was the first to be implemented in a conventional ultrasound scanner by Siemens(\uae) 8. Several articles have been published regarding this technology, most with the best reference standards 9, some including findings on more than 1000 hepatitis C patients 10 or reporting meta-analysis of data 11. Although the correlation between Siemens pSWE and transient elastography appeared high 12 13, the calculated thresholds for the different fibrosis stages and the stiffness ranges between the two techniques are not superimposable.Interestingly, pSWE appears to provide greater applicability than transient elastography for measuring both liver 13 and spleen stiffness, which is a new application of elastography 14, of interest for the prediction of the degree of portal hypertension 15 16.Nowadays other companies have started producing equipment with pSWE technology, but only very few articles have been published so far, for instance describing the use of Philips(\uae) equipment, which was the second to provide pSWE. These articles show preliminary good results also in comparison with TE 17 18. Not enough evidence is currently available in the literature about the elastographic performance of the products most recently introduced to the market. Furthermore, with some products the shear wave velocities generated by a single ultrasound acoustic push pulse can be measured in a bidimensional area (a box in the range of 2\u200a-\u200a3\u200acm per side) rather than in a single small point, producing a so-called bidimensional 2D-SWE 1. The stiffness is depicted in color within the area and refreshing of the measurement occurs every 1\u200a-\u200a2 seconds. Once the best image is acquired, the operator chooses a Region Of Interest (ROI) within the color box, where the mean stiffness is then calculated. 2D-SWE can be performed as a "one shot" technique or as a semi-"real-time" technique for a few seconds (at about 1 frame per second) in order to obtain a stable elastogram. With either technique, there should be no motion/breathing during image acquisition. A bidimensional averaged area should overcome the limitation of pSWE to inadvertently investigate small regions of greater or lesser stiffness than average. A shear wave quality indicator could be useful to provide real-time feedback and optimize placement of the sampling ROIs, a technology recently presented by Toshiba(\uae), but which is still awaiting validation in the literature.Supersonic Imagine by Aixplorer(\uae) which works with a different modality of insonation and video analysis compared to the the previously-mentioned three techniques (i.\u200ae., transient elastography, pSWE and 2D-SWE), leading to a bidimensional assessment of liver stiffness in real time up to 5\u200aHz and in larger regions; thus this technique is also termed real-time 2\u200aD SWE. It has been available on the market for a few years 19 20, and many articles have been published showing stiffness values quite similar to those of Fibroscan(\uae) 21; likewise, defined thresholds based on histological findings have appeared in several articles 19 20 21.After this brief summary of the technological state of the art we would like to mention the following critical issues that we believe every user should note prior to providing liver stiffness reports. \ub7 The thresholds obtained from the "oldest" techniques for the various fibrosis stages based on hundreds of patients with histology as reference standard cannot be straightforwardly applied to the new ultrasound elastography techniques, even if based on the same principle (e.\u200ag. pSWE). In fact, the different manufacturers apply proprietary patented calculation modes, which might result in slightly to moderately different values. It should be kept in mind that the range for intermediate fibrosis stages (F1 to F3) is quite narrow, in the order of 2\u200a-\u200a3 kilopascal (over a total range spanning 2 to 75 kPa with Fibroscan), so that slightly different differences in outputs could shift the assessment of patients from one stage to another. Comparative studies using phantoms and healthy volunteers, as well as patients, are eagerly awaited. In fact, the equipment might not produce linear correlations of measurements at different degrees of severity of fibrosis. As a theoretical example, some equipment might well correlate in their values with an older technique, such as transient elastography, at low levels of liver fibrosis, but not as well in cases of more advanced fibrosis or vice versa. Consequentely, when elastography data are included in a report, the equipment utilized for the measurement should be clearly specified, and conclusions about the fibrosis stage should be withheld if an insufficient number of comparative studies with solid reference standards are available for that specific equipment.. \ub7 Future studies using histology as a reference might be biased in comparison to previous studies, since nowadays fewer patients with chronic hepatitis C or hepatitis B undergo biopsy. In fact, due to wide availability of effective drugs as well as the use of established elastography methods for patients with viral hepatitis, most cases submitted to biopsy today have uncertain etiology or inconsistent and inconclusive clinical data. Therefore, extrapolated thresholds from such inhomogeneous populations applied to more ordinary patients with viral hepatitis might become problematic in the future, although no better solution is currently anticipated. This situation might lead to the adoption of a standard validated elastographic method as reference, but this has to be agreed-upon at an international level.. \ub7 Ultrasound elastography embedded in conventional scanners usually allows the choice of where to place the ROI within the color stiffness box and whether to confirm or exclude each single measurement when determining the final value. Thus, the operator has a greater potential to influence the final findings than with Fibroscan\uae, where these choices are not available. This has to be kept in mind to avoid the possibility that an operator could, even inadvertently, tend to confirm an assumption about that specific patient or to confirm the patient's expectations.. \ub7 Quality criteria for the new technologies following transient elastography are absent (depending on the manufacturer) or have not been satisfactorily defined, so that the information potentially inserted in a report cannot currently be judged for its reliability by the clinician.. (ABSTRACT TRUNCATED

Real-time in-flight engine performance and health monitoring techniques for flight research application

Various engine related performance and health monitoring techniques developed in support of flight research are described. Techniques used during flight to enhance safety and to increase flight test productivity are summarized. A description of the NASA range facility is given along with a discussion of the flight data processing. Examples of data processed and the flight data displays are shown. A discussion of current trends and future capabilities is also included

The use of real-time information in Phillips curve relationships for the euro area

The dynamics of the Phillips Curve in New Keynesian, Expectations Augmented and Hybrid forms are extremely sensitive to the choice, timing and restrictions on variables. An important element of the debate revolves round what information decision-makers took into account at the time and round what they thought was going to happen in the future. The original debate was conducted using up to date, revised estimates of the data as in the most recent official publications. In this paper, however, we explore how much three aspects of the specification of the information available at the time affect the performance of the various Phillips curves and the choice of the most appropriate dynamic structures. First we consider the performance of forecasts, published at the time, as representations of expectations. Second, we explore the impact of using 'real time data' in the sense of what were the most recently available estimates of the then present and past. Finally we review whether it helps to use the information that was available at the time in the choice of instruments in the estimation of the relationships rather than the most up to date estimate of the data series that has been published. Thus different datasets are required in the instrument set for every time period. We use a single consistent source for 'real-time' data on the past, estimates of the present and forecasts, from OECD Economic Outlook and National Accounts. We set this up as a panel for the euro area countries covering the period since 1977. The OECD publishes forecasts twice a year, which permits a more detailed exploration of the importance of the timing of information. Our principal conclusions are (1) that the most important use of real time information in the estimation of the Phillips curve is in using forecasts made at the time to represent expectations; (2) real time data indicate that the balance of expectations formation was more forward than backward-looking; (3) by contrast using the most recent, revised, data suggests more backward-looking and less well-determined behaviour. --real-time data,Phillips curve,euro area

Finding a Midpoint between Civil and Military Use. The Case of Villaputzu (Sardinia, Italy)

The paper addresses the issue of the concurrent use of areas for military and civil activities. In particular, the paper analyzes the effect of planning tools on the valorization of a territorial enclave, namely a military training area located in the coastal area of the municipality of Villaputzu (South Sardinia, Italy), that is, moreover, a Site of Community Importance. In this area, thanks to an institutional agreements between the Municipal Administration of Villaputzu and the Ministry of Defense, has been possible define the coexisting ways where is an important coastal military easement. and the use of the coast for recreational tourism purposes through a specific planning tool. In this specific case, the Local Coastline Plan (LCP) has been identified as the planning tool, which better addresses the co-existence of apparently opposite land uses and interests, as those expressed by the local municipality and those expressed by the military hierarchy. The assessment method is based on the capacity of the Local Coastline Plan (LCP) and the Site of CommunityInterest Management Plan (SCIMP) to create ecosystem services in the military enclave. The evaluation of the LCP and SCIMP shows how their combined action favors the environmental enhancement of territory, contributing to the formation of ecosystem services, The area, initially subject to different constraint (military easements and SIC rules) evolve, by that way, from ‘anticommons’ to ‘semicommons’, guaranteeing sustainable renewal of economic development of the area and looking to become ‘commons’ through planning of ecosystem services

Real-time macroeconomic data and ex ante predictability of stock returns

We report results on the ex ante predictability of monthly excess stock returns in Germany using real-time and revised macroeconomic data. Our real-time macroeconomic data cover the period 1994-2005. We report three results. 1) Real-time macroeconomic data did not contribute much to ex ante stock-return predictability. 2) The performance of an investor who had to rely on noisy real-time macroeconomic data would have been comparable to the performance of an investor who had access to revised macroeconomic data. 3) In real time, it is important for an investor to know which real-time variable to use for predicting stock returns. --Ex ante predictability of stock returns,real-time macroeconomic data,performance of investment strategies,Germany

LEAN PANEL BENDER – Einige mechanische Aspekte der Modellierung in Echtzeit für Produktion in Losgröße 1

Nachfolgend werden einige wissenschaftliche Aspekte der Echtzeit-Materialerkennungsstrategie MAC diskutiert, die in der neuen Maschinenfamilie LEAN PANEL BENDER der Firma Salvagnini Maschinenbau realisiert ist und die eine hochpräzise und hocheffiziente Herstellung von komplex geformten Blechprodukten sowohl bei Losgröße 1 als auch in der Serie erlaubt.(VLID)342339

Realtime 3D graphics programming using the Quake3 engine

We present a lab assignment that accompanies a complete module called Real-time Graphics . The students task is to get familiar with content creation and programming a (previously) commercial 3D engine. In a first task, students have to create 3D content, which is integrated into the Quake3 engine. In a second task, the students have to implement a simple animation and finally add an impressive 3D graphics effect to the Quake3 engine. The lecture has been taught four times from 2004 to 2007. We present the assignment and report on experiences that we have gained

City Information Modeling – Potenziale für eine intelligente Stadtplanung

Dreidimensionale Darstellungen haben sich in der Stadtplanung als unverzichtbares Kommunikationsmedium etabliert. Primär fungieren sie derzeit als unterstützendes Instrument in Bürgerbeteiligungsprozessen und bei der Darstellung von Planungsalternativen als Entscheidungshilfe. Moderne computergestützte Architekturmodelle erfahren seit jüngster Zeit eine Weiterentwicklung der herkömmlichen Planungsmethoden. Unter dem Begriff des Building Information Modeling zusammengefasst, lassen sich mit dieser neuen Methode virtuelle Modelle erzeugen, deren Informationsgehalt gegenüber klassischen virtuellen Modellen um ein Vielfaches höher ist. Zudem finden sie nicht nur in einzelnen Planungsphasen Anwendung, sondern begleiten ein Projekt über den gesamten Gebäudezyklus hinweg. Um die Vorteile und Potenziale solch intelligenter Modelle ausschöpfen zu können, gilt es nun diesen Ansatz auch für die Stadtplanung weiterzuentwickeln und auf diese zu übertragen. Mit diesem Ansatz des City Information Modeling ist es beispielsweise möglich, über die reine Erfassung geometrischer Formen hinaus, Bilanzen zu erstellen, versorgungsinfrastrukturelle Daten einzupflegen, objektspezifische Informationen zu hinterlegen und diese anschließend in automatisierten Prozessen auszuwerten und zu analysieren. Das hier vorgestellte Paper ist eine Kurzfassung der Arbeit „City Information Modeling – Potenziale für eine intelligente Stadtplanung“ (MÜLLER 2015) die am Fachgebiet CPE der TU Kaiserslautern entstanden ist. Die im Rahmen dieser Arbeit untersuchten Anwendungen zeigen auf, dass es mittels aktueller Software möglich ist, den Informationsgehalt von Planungen deutlich zu erhöhen

Ko-Automobilität. Heutige Nutzungsformen und Nutzungsmuster in Deutschland und Verbreitungspotenziale als alternatives Mobilitätsangebot

Das Projekt "Autoteilen" beschäftigt sich mit den Möglichkeiten der gemeinschaftlichen/geteilten Nutzung des Pkws. Einhergehend mit der fortschreitenden Digitalisierung und Informations- und Kommunikationstechnologien (KIT) entwickelt sich eine Vielfalt neuer Nutzungsformen im Bereich Peer-2-Peer-Sharing. Im Rahmen des Projekts werden die verschiedenen Formen des Pkw-P2P-Sharings untersucht, die Nutzer sowie ihre Motive und Anforderungen bzw. Nutzungsbarrieren betrachtet und eine Aussage zum künftigen Verbreitungspotenzial getroffen