[en] McCune-Albright syndrome is a genetical disease with a mosaic distribution. It is characterized by skin pigmentations, fibrous dysplasia and sexual precocity but can also include others endocrinopathies. Two cases are reported illustrating the interest of radiological investigations in diagnosis, follow up and complications of this affection. (authors)

[en] Magnetic resonance imagery is essential based on the hydrogen nucleus, proton imagery. Proton density (ρ), longitudinal relaxation time (T1) and transversal relaxation times (T2) are the main tissue parameters controlling contrast. The different parameters can be used to improve the acquisition sequences (weighting). Sequential parameters, displayed by the machine, control contrast weighting and are basically repetition times, echo time and the shift angle α. The aim of this work was to explain, without unnecessary mathematical formulas, how contrast is achieved in magnetic resonance imagery based on the main types of sequences used today. (authors). 8 refs., 22 figs

[en] Infection, neoplastic involvement, and hemorrhage, are the most frequent pathologies that involve the ilio-psoas compartment. The extension from contiguous pathological structures and particularly digestive and urological organs, are often the origin of abscess formation or malignant tumours. The radiological findings including ultrasonography, CT, and magnetic resonance imaging, show a low specificity, which improves if the clinical history is known. The final diagnosis is confirmed by puncture or biopsy. (author)

[en] The regulations in radioprotection compel to reduce radiations as much as possible without decreasing the quality of information. The aim of this article is to define quality assurance and to recall the texts used as a basis for this concept. The criteria of evaluation of image quality are developed. The dose of irradiation must be correlated with quality. Substantial reductions of dose are possible without significant loss of information. This article deals also with the bases of training in radioprotection. (authors). 17 refs., 5 figs., 7 tabs

[en] Artefacts in MR can take the form of variation in signal intensities or mispositioning of signal that can be misleading because they alter the appearance of the image. This paper covers the most common artefacts, that must be recognized andly understood in order to accurately interpret MR findings. Each type of artefact will be illustrated, briefly explained and followed by practical suggestions for avoiding or reducing it. At the end of the paper a table will resume the essential notions to be remembered. (authors). 27 refs., 35 figs

[en] Up until now, commercialized MRI contrast agents included only gadolinium chelates which have a non specific interstitial distribution. New agents are being developed and commercialized, which are specially directed towards an organ or a function. This review paper first focuses on the mechanisms of the modifications in the T1 and T2 relaxation times and in the signal, with an emphasis on the two possible results: increase in signal (T1 effect) and decrease in signal (T2 effect). The different agents under development are then successively described: hepatobiliary agents (Gd-EOB-DTPA. Gd-BOPTA, Mn-DPDP), liver and lymph node-specific agents (superparamagnetic nano particles), macromolecular blood-pool agents (dextran-Gd-DTPA). For each agent, the biological behavior is described, the principal preclinical results and the clinical interests in MR imagining are reported. (authors). 47 refs., 11 figs., 7 tabs

[en] Management of voluminous adrenal gland tumor (> 5 cm) is a clinical challenge. Only 33 % of these lesions are malignant. Surgical treatment is not always necessary. Several investigations as biochemical assessment, nuclear medicine, studies, arteriography, computed tomography or magnetic resonance imaging are useful in order to approach the diagnosis. Unfortunately, none has sufficient diagnostic specificity to distinguish malignant from benign lesions. After a review of clinical, biochemical, radiological characteristics of the main adrenal gland tumors, we have defined the advantages and the defaults of different imaging modalities. A simple management plan of voluminous adrenal gland lesion is proposed. The study is based upon the analysis of 63 cases reported by several authors. (authors). 16 refs., 6 figs

[en] Modern imaging techniques, computed tomography (CT) and magnetic resonance imaging (MRI), have a major role in the diagnosis and the management of pleural tumors. CT is the most accurate technic for the diagnosis of these benign or malignant diseases. CT allows to depict small pleural thickening, nodules, masses with or without pleural effusion. Pleural tumors may occur as a focal or diffuse disease. (authors). 28 refs., 6 figs., 3 tabs

[en] Most of the time, rationales to look for pituitary micro-adenomas are based on endocrinal disorder. MRI is often helpful to confirm diagnosis. It gives information about micro-adenomas size and localisation. If conventional sequence are inadequate, a dynamic sequence has then to be performed after Gadolinium injection. Any disorder observed from the pituitary gland must be correlated with the clinical observation and results from biochemistry analysis. False positive happens quite open because of gland morphological variation, incidentalomas and partial volumes. MRI offers the possibility to follow-up treated micro-adenomas evolution especially to detect recurrence. (author)

[en] The effect of low doses of X-rays is inferred from the indubitable effects of high doses in human carcinogenesis, Genetic and teratogenic effects are mainly inferred from animal experimentation because clinical surveys of irradiated pregnant women have failed to demonstrate such consequences in the children, except for mental retardation after Japanese atomic bombing. Since no evidence of carcinogenic effect has been produced by epidemiological studies for doses lower than 500 mSv. the estimation of the risk due to low doses has been extrapolated from the linear relation between dose and cancers at high doses. Such an extrapolation gives a maximal risk which is falsely used as a probability of cancer. The actual risk lies between zero and this maximal number, and many epidemiologic surveys in people receiving doses much higher than the mean level of background irradiation failed to demonstrate higher rate of cancer. The explanation of this fact, which is supported by the most recent biological data, is the efficacy of the DNA repair system at low level of exposure to ionizing radiations. We expose the principles of regulation of radioprotection for workers, and give estimations of the doses delivered to the patients and the personnel by diagnostic investigations, by comparing these doses with those of natural irradiation. Practical aspect for conventional and computed radiology are exposed for patients and workers. (authors)