EMC - Radiologie最新文献

Barium studies as endoscopy provide exquisite delineation of mucosal pathologic features. The precise description of radiographic characteristics in conjunction with site and size of the lesion and the clinical history enables the radiologist to formulate a specific diagnosis or a graded differential diagnosis. Although mucosal abnormalities and small mass lesion are beneath its spatial resolution, sonography like computed tomography (CT) and MR Imaging excels in demonstrating the extramucosal component of gastrointestinal tract disease and in detecting extra intestinal complications.

Endometriosis is characterised by ectopic endometrial tissue, which can cause dysmenorrhoea, dyspareunia, non-cyclical pelvic pain, and sub fertility. Final diagnosis is made by laparoscopy, but can also be helped by imaging. Most endometrial deposits are found in the pelvis (ovaries, peritoneum, uterosacral ligaments, pouch of Douglas, and rectovaginal septum). Extra pelvic deposits, including those in the umbilicus and diaphragm, are rare. Endometriomas are cysts of endometriosis within the ovary. Endometrial implants are responsible of pelvic adhesions or visceral infiltration. Consequences of these disease are often severe, from pelvic chronic pain until ureteral or rectal invasion. Diagnosis is difficult. Ultrasonography is able to detect ovarian endometriomas or adenomyosis but can not detect deep posterior endometriosis. MRI. is actually the more accurate examination for diagnosis and presurgical staging for endometriosis. Nevertheless, the knowledge of MRI technical parameters, and rules of interpretation are necessary for diagnosis accuracy, due to difficulty to detect the lesions. In this review, we will successively describe endometriosis physiopathology and imaging with different locations, with a particular attention to MRI, in order to allow adequate diagnosis and staging.

The increasing number of nonpalpable breast lesions, detected at screening mammography, has induced the development of percutaneous imaging-guided procedures to reduce the number of diagnostic surgical biopsies. After a description of the indications (classification of the American College of Radiology), the different imaging modalities, the material used and the sampling procedures (ultrasound, mammography with stereotaxy, fine needle aspiration, micro and macrobiopsies and stereotactic surgery) will be described. Results of the different percutaneous procedures will be discussed. Clear information to the patients, efficient quality control and multidisciplinary approach are mandatory for the success of these percutaneous diagnostic procedures. Localization techniques before surgery will be presented.

Positron Emission Tomography (PET) is a medical imaging modality, which provides the in-vivo distribution of a compound labeled by a positron emitter. The acquisition is peformed by a set of detector fitted on a ring. The detector is based on a scintillator chosen in order to optimize the efficiency and the signal to noise ratio. Coincidence detection is dedicated to measure the two 511 keV photons resulting from the annihilation of the positron. Tomographic slices are reconstructed thanks to sophisticated algorithms adapted to the tri dimension acquisitions. The quantification of PET images is achieved by the correction of the main physical effects that alter the detection process. For the patient, the effectives doses resulting for a PET examination is about 8 mSv. The installation of a PET device requires specific investments to ensure the radioprotection of the staff. The PET evolution is very fast, this is particularly important for the detectors and for the algorithms. Recently, a new generation of PET/CT devices has been developed to benefit of the complimentarity of both modalities. The CT images can be used for attenuation correction, to localize the lesion detected by PET and to optimize the therapeutical procedures. Thanks to all these developments, PET is a powerful diagnostic tool among the other medical imaging modalities.

The acute infectious pneumonia constitute a problem of public health because they are one cause of great morbidity and mortality in adult. If the clinical and radiological information allow often to achieve the diagnosis of infectious pneumonia, the etiologic diagnosis is more difficult. Indeed, numerous pathogen germs are responsible of pneumonia and the reaction of lung is not very various, this explain the low specificity of radiological imaging, except for few characteristic cases. That’s why the understanding of physiopathologic mechanisms allow to explain some special cases. In the same way, the knowledge of anatomical and radiological understanding allow the acknowledgment of three main radiographic appearance. As for the evaluation of epidemiological and immune contexte, they can allow to recognize the concern germ.

This article studies the aim of ultrasounds for the follow-up of first trimester normal or pathological pregnancy. Two periods are analysed : before and after 11 weeks of gestation. Thus are particularly studied : fetal nuchal translucency and her aim for appraise the risk of aneuploidy, first study of fetal anatomy and detection of fetal structural abnormalities, multiple gestations and diagnostic of chorionicity