THE INTEREST OF IMAGING: Mammography permits diagnosis of infra-clinical breast lesions with a sensitivity of around 80%. Moreover, with the improvement of the apparatuses and films, the latter permit analysis of the breast areas in most cases. Sonography, indisputable support for the study of dense breasts, is a complement to mammography and clinical examination. Magnetic resonance imaging is the most sensitive technique, but cannot be used in routine controls. The principle images are essentially opacities characterised by enhanced density in the glandular parenchyma (circular or round, asymmetrical opacities of architectural density and disorganisation, stellar and epiculated opacities) and micro-calcifications without specific appearance, revealing when isolated in situ intra-ductal or micro-invasive lesions. THE INTEREST OF BIOPSY PROCEDURES: For non-palpable tumours discovered on imaging, stereo or radio-guided cytological aspirations are proposed so long as the image is not too small. In the presence of infra-clinical images inaccessible to guided cytology, stereotaxy micro-biopsies can be performed. The relative insufficiency of results obtained has led to the proposal of needles of larger calibre used in an apparatus called a mammotome or in the ABBI system, the latter permitting radio-guided surgical excision. PRIORITY GIVEN TO CLINICAL CONTROLS: The technical progress must not lead one to neglect the clinical examination, which, in 5 to 30% of cases, reveals a cancer when the mammography or sonography does not.

In a first part, the different techniques of digital thoracic radiography are described. Since computed radiography with phosphore plates are the most commercialized it is more emphasized. But the other detectors are also described, as the drum coated with selenium and the direct digital radiography with selenium detectors. The other detectors are also studied in particular indirect flat panels detectors and the system with four high resolution CCD cameras. In a second step the most important image processing are discussed: the gradation curves, the unsharp mask processing, the system MUSICA, the dynamic range compression or reduction, the soustraction with dual energy. In the last part the advantages and the drawbacks of computed thoracic radiography are emphasized. The most important are the almost constant good quality of the pictures and the possibilities of image processing.

In a first part, the different techniques of digital thoracic radiography are described. Since computed radiography with phosphore plates are the most commercialized it is more emphasized. But the other detectors are also described, as the drum coated with selenium and the direct digital radiography with selenium detectors. The other detectors are also studied in particular indirect flat panels detectors and the system with four high resolution CCD cameras. In a second step the most important image processing are discussed: the gradation curves, the unsharp mask processing, the system MUSICA, the dynamic range compression or reduction, the soustraction with dual energy. In the last part the advantages and the drawbacks of computed thoracic radiography are emphasized, The most important are the almost constant good quality of the pictures and the possibilities of image processing.

But de l'étude : Le but de ce travail est de présenter une synthèse des différents progrès réalisés dans le domaine des ponctions abdominales guidées par scanner. Ces améliorations permettent d'augmenter la rentabilité des ponctions et de diminuer le nombre de complications. Les principales améliorations concernent les techniques de guidage avec en particulier l'apparition de scanners ultra-rapides, les systèmes de biopsies automatiques qui permettent d'augmenter la taille des prélèvements et d'améliorer leur qualité, et les nombreux artifices techniques permettant un accès plus facile de la lésion à biopsier, en mobilisant le patient et/ou en déplaçant certaines structures anatomiques. De plus, une meilleure prise en charge des prélèvements effectués passe par une étroite collaboration avec l'anatomopathologiste. Cette étude se termine par une synthèse des complications des biopsies guidées par scanner, qui sont rarement observées. How to improve the accuracy of abdominal CT-guided biopsies? Study aim: The aim of this paper is to present an overview of the various technical progresses made in the field of CT-guided abdominal biopsies. Recent improvements allowed to markedly increase the efficiency of biopsies and to decrease the number of complications. The main innovations concern the guidance technique itself with the availability of ultra-fast CT systems, the development of automated biopsy systems, which allow to improve the size and quality of tissue samples and numerous technical tricks, allowing an easier access to target lesions, either in patient positioning or in displacement of anatomical structures. A better management of tissue samples favored by a close collaboration with pathologists is also mandatory. The last section of the paper is an overview of the rare complications of CT-guided biopsies.

In several medical centers computed radiography has almost completely replaced the use of conventional screen-film systems for general radiography. The aim of this paper is to explain the basic principles of the four most frequently numerical detectors used in the world, with emphasis on the phosphor plates, which are the most frequently used both in hospitals and by practitioners. The other two systems are based on a receptor with selenium. The fourth uses charged coupled device (CCD) detectors. The most important principles of digital processing are then described with concentration on unsharp mask filtering. In the future computed radiography will replace standard radiology and will create a system in medicine using the power of computers to archive - with more efficiency and less space - patient medical data. The transmission of data to workstations and the processing of this data is the topic of a new field in medicine.