Digital chest radiography: an update on modern technology, dose containment and control of image quality

The introduction of digital radiography not only has revolutionized communication between radiologists and clinicians, but also has improved image quality and allowed for further reduction of patient exposure. However, digital radiography also poses risks, such as unnoticed increases in patient dose and suboptimum image processing that may lead to suppression of diagnostic information. Advanced processing techniques, such as temporal subtraction, dual-energy subtraction and computer-aided detection (CAD) will play an increasing role in the future and are all targeted to decrease the influence of distracting anatomic background structures and to ease the detection of focal and subtle lesions. This review summarizes the most recent technical developments with regard to new detector techniques, options for dose reduction and optimized image processing. It explains the meaning of the exposure indicator or the dose reference level as tools for the radiologist to control the dose. It also provides an overview over the multitude of studies conducted in recent years to evaluate the options of these new developments to realize the principle of ALARA. The focus of the review is hereby on adult applications, the relationship between dose and image quality and the differences between the various detector systems

Design and performance of a DNP prepolarizer coupled to a rodent MRI scanner

For most of the last forty years, the techniques of Dynamic Nuclear Polarization (DNP) have been confined to particle-physics laboratories building polarized targets, but recently it has been shown that samples similar to a solid target can be transformed into room temperature liquid solutions while retaining a high nuclear polarization. This method of "hyperpolarization" is of interest in NMR/MRI/MRS. We describe a 3.35 T DNP/9.4 T MRI installation based on a continuous-flow cryostat, using a standard wide-bore low-field NMR magnet as prepolarizer magnet and a widely available radical as polarizing agent. The interfacing to a rodent scanner requires that the infusion of the polarized solution in the animal be remotely controlled, because of limited access inside the magnet bore. Physiological constraints on the infusion rate can be a serious source of polarization loss, and the discussion of efficiency is therefore limited to that of the prepolarizer itself, i.e., the spin temperatures obtained in the solid state. To put our results in context, we summarize data obtained in targets with different types of radicals, and provide a short review of the DNP mechanisms needed in their discussion. (C) 2007 Wiley Periodicals, Inc

Unconventional Gas Resources in the Paleozoic of Central Europe Ressources de gaz non conventionnels dans le Paléozoïque de l’Europe Centrale

Whereas gas production from unconventional reserves has greatly increased over the past decades, there is still a largely unexplored potential in the Paleozoic of Central Europe. For this area, the paper summarizes some important aspects of the geology of tight sandstone gas reservoirs, gas shales and coalbed methane. Tight sandstones with low permeabilities are especially present in the Permian (Rotliegend Formation) of The Netherlands and northern Germany, but also in the underlying Carboniferous. There is already active production from some of these reservoirs. Further development greatly depends on understanding of gas charge as well as the regional distribution of porosity and permeability which in turn depend on facies and diagenesis. In contrast exploration for gas shales is just at the very beginning. Whereas Mesozoic shales in the southern Lower Saxony Basin have to be regarded as prime targets due to thickness, maturity and organic matter content, there are additional targets in the Mississippian, but also in older rocks. Currently an international gas shale research programme (Gas shales in Europe, GASH) gathers relevant data for these units. Coalbed methane exploration started already about 20 years ago in the Ruhr Basin, but was not successful at that time due to small flow rates. On the other hand, production from abandoned coal mines provided substantial amounts of gas. Due to the abundance of coal seams and the suitable maturity conditions and gas contents, there is a high potential for future substantial coalbed methane in the area. <br> Alors que l’extraction du gaz naturel des gisements non conventionnels a fortement augmenté ces dernières dizaines d’années, un large potentiel de ressources reste inexploré dans les couches paléozoïques de l’Europe Centrale. Cet article présente, pour cette région, quelques aspects importants de la géologie des grès de faible perméabilité (tight gas sands), des gaz de schiste (gas shales) et du gaz de houille (coalbed methane, CBM). Les grès de faible perméabilité se trouvent surtout parmi les couches permiennes (Rotliegend) aux Pays-Bas et dans le nord de l’Allemagne, mais aussi dans les couches du Carbonifère supérieur. La production est déjà active dans quelques-uns de ces réservoirs. Pour l’avenir, le développement dépendra principalement de l’amélioration de la compréhension du gaz en place et de la distribution régionale de la porosité et la perméabilité qui, d’ailleurs, dépendent du faciès lithologique et la diagénèse. La recherche de gaz dans les roches argileuses, par contre, vient juste de commencer. Les roches argileuses mésozoïques dans le sud du bassin de Basse-Saxe (Lower Saxony Basin) sont des objets d’exploration prioritaire à cause de leur épaisseur, de leur maturité et de leur teneur en matière organique. Mais il existe d’autres séries intéressantes dans le carbonifère inférieur et des couches plus anciennes. Actuellement, un projet de recherche international vise à acquérir des données géologiques sur ces systèmes. La recherche du gaz de houille (CBM) a commencé dans la bassin de la Ruhr il y a une vingtaine d’années, mais avec un succès très limité à cause de faibles débits de gaz. En revanche, le captage de grisou des mines de charbon abandonnées a fourni de considérables quantités de gaz. De par la multitude des filons houillers et des conditions de maturité et de teneurs en gaz favorables, il existe dans cette région un potentiel considérable de gaz de houille

Autoantibody profiling as early diagnostic and prognostic tool for rheumatoid arthritis

Background: Early treatment prevents progression of joint damage in rheumatoid arthritis (RA), but diagnosis in early disease is impeded by lack of appropriate diagnostic criteria. Objective: To study the value of rheumatoid factor (RF), anti-cyclic citrullinated peptide autoantibodies (anti-CCP), and anti-RA33 autoantibodies for diagnosis of RA and prediction of outcome in patients with very early arthritis. Methods: The prospective follow up inception cohort included 200 patients with very early (<3 months) inflammatory joint disease. Autoantibodies were measured at baseline and analysed in a tree based model which aimed at determining the added diagnostic value of testing for anti-CCP and anti-RA33 as compared with RF alone. Results: RA was diagnosed in 102 patients, while 98 developed other inflammatory arthropathies. Receiver operator curve analysis showed an optimum cut off level for RF at 50 U/ml, above which anti-CCP and anti-RA33 had no additional diagnostic value. Remarkably, RF ⩾50 U/ml and anti-CCP showed similar sensitivity and high specificity for RA, but overlapped considerably. Anti-RA33 was less specific and did not correlate with RF or anti-CCP. Among patients with RA, 72% showed at least one of these three autoantibodies, compared with 15% of non-RA patients. RF ⩾50 U/ml and anti-CCP were predictors of erosive disease, whereas anti-RA33 was associated with mild disease. Conclusions: Stepwise autoantibody testing in early inflammatory joint disease, starting with RF, followed by anti-CCP (in patients with RF <50 U/ml), and finally anti-RA33, should be used as a sensitive and effective strategy for distinguishing patients with RA at high risk for poor outcome

Receiver Architecture, Multimedia Car Platform (MCP), Technical Report, Deliverable 8B, March 2001

This document presents the second and full version of the terminal architecture for the Multimedia Car Platform. It describes architectural insights and motivations, an overview of the API framework , the status of the MHP (Multimedia Home Platform) and necessary extensions for an evolution towards MCP. This document completes the preliminary version Part A. The first mobile multimedia terminal in Europe and possibly in the world will enable the users to select from a bouquet of applications and data conveyed over different network topologies and services. The user should be unaware of which network is actually used to get the information through the most adequate network depending on the service necessities. Inspired by the success of the Internet, the MCP terminal should be an open platform, allowing for a wide bouquet of x-tainment applications. The Multimedia Car Platform will be strongly based on the Multimedia Home Platform specification defined under DVB, and thus support Java applications. However, the fact that we encounter different requirements pertaining to a terminal operated in a moving car has wide reaching impacts on the MCP specification. Therefore, necessary extensions to the MHP are examined. This comprises additional APIs, relating to navigation/positioning functions and maps, speech I/O, phone operation, interaction channel support, and various forms of in-car communication and access to car relevant information. The drastic differences regarding security between systems like MCP - where human life and safety are at stake - and the home internet require a technical platform with enhanced security and certification models that allow for various levels of trusted applications with different levels of access to the platforms functions. The security model described in this document allows a trusted centre to finely define this framework, taking into account legal, usability, integrity, privacy, and other concerns. It works by introducing the concept of application specific policeman that guard the platform and thus the human users. The extended application management concept includes extended life-cycle management, support for stored applications and stand-alone applications, more detailed priority handling and a refined resources management. The use of Jini technology in MCP as an extended profile can bring many advantages to the car platform. It allows for a high flexibility in adding future devices, applications, which had not been foreseen a priori. We envision a Jini API that wraps Jini services such as Lookup, Join, or Discover in a secure fashion and makes these available to trusted applications and devices