Filters
Results 1 - 10 of 128
Results 1 - 10 of 128.
Search took: 0.033 seconds
| Sort by: date | relevance |
[en] The most commonly used technique for CT of the liver are dynamic CT scanning after either IV, direct hepatic arterial or indirect portal contrast injection. The need for these different approaches is because compromises have to be made which take into account the scanner performance, the pharmacodynamics of the available urographic contrast agent and the complex vascularisation of the liver and the tumors. Spiral scanning is a novel technique which allows to scan the entire liver in a single breathhold period of about 10 to 20 seconds with the a posteriori calculation of perfectly contiguous or even overlapping slices. These two new specifications offer entirely new perspectives in terms of liver enhancement. It becomes theoretically possible to scan the entire liver twice, during both the early arterial phase and the subsequent venous phase after one single short IV bolus injection. Hence the total amount of contrast media to be administered can be reduced while the diagnostic potential of the contrast agent is significantly increased. (orig.)
[de]
Dynamische CT-Untersuchungen der Leber werden in der Regel nach bolusartiger intravenoeser Kontrastmittelgabe durchgefuehrt. Alternativ werden direkte Kontrastmittelinjektionen in die A. hepatica, A. lienalis oder A. mesenterica superior vorgenommen. Diese verschiedenen Zugangswege sind erforderlich, um den besten Kompromiss zu finden zwischen der technischen Leistung des CT-Geraetes, der Pharmakodynamik der verwendeten Kontrastmittel und dem komplexen Gefaessmuster der Leber und der Tumoren. Mit der neuentwickelten Technik des Spiral-CT kann die gesamte Leber im Atemstillstand innerhalb von 10-20 s untersucht werden. Die Berechnung der kontinuierlichen oder ueberlappenden Schnitte erfolgt im Nachhinein. Diese Technologie eroeffnet neue Perspektiven fuer die Kontrastmitteluntersuchung der Leber. Es ist zumindest theoretisch moeglich, die ganze Leber 2x zu untersuchen, naemlich einmal in der frueharteriellen Phase und dann in der venoesen Phase nach einer einzigen kurzen Bolusinjektion. Auf diese Weise koennte mit einer reduzierten Kontrastmitteldosis die diagnostische Aussage verbessert werden. (orig.)Journal
[en] Two types of MR angiography techniques are used in the radiological practice for neurovascular applications: flow based techniques and ultrafast contrast enhanced acquisitions. Both techniques have their specific advantages and limitations. Whereas flow based techniques can be run on most MR scanners, high quality contrast enhanced studies require a state-of-the-art system with high slew rates and dedicated tools to match bolus passage and MR scanning. In this text, we focus on the physical acquisition principles and we illustrate the different phenomena in clinical examples. Numerous studies have proven the clinical applications for the 2 acquisition strategies. So far, an understanding of the basic physics remains necessary to explain occasional artefacts: MR angiography techniques are not yet fully robust. Further optimizations of the current approaches can be expected as there is still a need to improve image quality
Journal
[en] The assessment of the dose-image quality relation using storage phosphor systems requires a series of tasks. In the text, the main aspects are summarised and the differences with the measurements for X ray equipment using film-screen cassettes are indicated. Standards of testing are becoming available for quality control measurements of the equipment. The global analysis is, however, less standardised. Large scale trials concerning dose and image quality are missing. In particular, guidelines about the appropriate use of post processing parameters and image visualisation are scarce. In this regard, a newly proposed method to evaluate image quality as a function of post-processing parameters for particular types of clinical images is mentioned. It is concluded that a thorough analysis may be very time consuming, but if the properties of the digital detectors are exploited, many tasks can be automated. (author)
Journal
[en] The delayed-type hypersensitivity (DTH) reaction observed in mice primed i.v. with low doses of sheep red blood cells was greatly decreased when mice were irradiated with 300 rad before priming. An estimation of the radiosensitivity of DTH-mediating cells (DTH-C) was performed using a titration assay after local adoptive transfer of these cells mixed with antigen into the footpad of unprimed mice. A high radiosensitivity of the induction of DTH-C was observed with a D37 of approximately 50 rad. In contrast, the expression of DTH-C appeared radioresistant, as the D37 was approximately 2000 rad. (author)
Journal
Immunology; ISSN 0019-2805; 
; v. 37(1); p. 273-278
; v. 37(1); p. 273-278
[en] Several excellent imaging modalities are available for studying the great vessels of the chest noninvasively. Besides computed tomography (CT), magnetic resonance imaging (MRI) and echocardiography (in particular the transesophageal approach) can accurately depict abnormalities of the thoracic vasculature, and are a valuable substitute for contrast angiography in most circumstances. The aim of this paper is to provide a comprehensive review of the current contribution of CT and MRI to the diagnosis of great vessel pathology of the chest. (orig.)
Journal
[en] Thirty nine patients with one or more focal hepatic lesions were examined by contrast enhanced computed tomography (CE-CT) and magnetic resonance imaging (MRI). A variety of pulse sequences - spin echo (SE), gradient echo (GE) and inversion recovery (IR) - have been reported in the literature on MRI concerning the detection and characterization of liver tumors. Multiple studies have compared MRI at different field strenghts to CT. As controversy still exists concerning the optimal pulse sequence on MRI, CE-CT has been compared to T2 weighted SE sequence in this study. CT, as well as MRI, identified abnormalities in liver parenchyma in all patients. As far as detection of hepatic lesions is concerned, MRI and CE-CT were equal in 35 cases and MRI was superior in the other four cases. However, CT remains the examination of choice for detection of focal lesions, due to the short examination time, the low cost and the superiority in detection of extrahepatic pathology
[fr]
Trente-neuf patients avec une ou plusieurs lesions focales intrahepatiques ont ete examines par tomodensitometrie (TDM) avec injection de produit de contraste iode et par imagerie par resonance magnetique (IRM). Dans la litterature une grande diversite de sequences - echo de spin (ES), echo de gradient (EG) et inversion recuperation (IR) - ont ete rapportees dans l'exploration IRM du foie. Plusieurs travaux ont en effet compare l'IRM a differents champs magnetiques a la TDM. Puisqu'il n'existe toujours pas de concordance en ce qui concerne la performance des differentes methodes d'imagerie, on a compare la TDM avec contraste iode intraveineux a une sequence ponderee en T2 en echo de spin, en utilisant une technique speciale pour compenser les artefacts de mouvements. La TDM, aussi bien que l'IRM, ont identifie des anomalies du parenchyme hepatique dans tous les cas. En ce qui concerne la detection de lesions hepatiques, l'IRM etait equivalente a la TDM dans 35 patients et superieure chez les 4 autres patients. Jusqu'a present la tomodensitometrie reste l'examen de premiere intention pour le depistage de lesions focales hepatiques puisque l'examen ne necessite que peu de temps, est peu couteux et parce qu'il est superieur pour la detection d'eventuelles pathologies extra-hepatiquesJournal
| 1 | 2 | 3 | Next |