Problème diagnostique posé par une lésion hépatique hypermétabolique en TEP à la fluorocholine (18F) : à propos d’un cas

IntroductionWe report a case of atypical fluorocholine (18F) PET/CT hypermetabolic hepatic lesion discovered during the staging of a prostate carcinoma.Case reportBecause of elevated PSA serum level, the patient had prostate biopsies which elicited an adenocarcinoma with a Gleason score of 8 (4 + 4). Pelvic MRI did not display any extracapsular disease extension. The PET/CT scan demonstrated a prostatic focal uptake and a liver increased uptake area matching with a segment VII hepatic nodule measuring 25 mm within a fatty liver, which was hypometabolic on the PET scan and hypodense on the CT scan. The liver ultrasound study reported the lesion as a focal spared area of healthy liver tissue within steatosis, whereas MRI diagnostic conclusion was inflammatory hepatocellular adenoma. When asking the patient, it appeared that the hepatic nodule had been known for 7 years, its size was unchanged, and, from previous radiologic imaging, it had been considered as an adenoma. However, there was no histological proof.DiscussionIn the interpretation of the PET/CT scan findings, we excluded a hepatocellular carcinoma and a prostate metastasis due to the long period of time during which the nodule had been followed up without significant change. We thought that focal nodular hyperplasia, which is fluorocholine avid, was the most likely diagnosis, knowing that hepatocellular adenomas, including the inflammatory type, have not been reported to display increased fluorocholine uptake. We noticed that the patient's fatty liver uptake was low, which could have accounted for a falsely increased uptake by the nodule. But, similarly to other authors, we could not find any relationship between CT density and fluorocholine uptake.ConclusionThis case shows a discrepancy between the radiologic and nuclear medicine findings. However, this hepatic nodule is likely to be benign because of the lesion characteristics and the patient medical history.     

Efficacité de la mémoire associative inhérente à la potentiation post-tétanique

An associative memory is modeled in networks of cells that are assumed to have the short-term plasticity of the neuromuscular junction of the frog. The data relating synaptic transmission efficiency and stimulation frequency for post-tetanic potentiation of the neuromuscular junction are represented by polynomial expansions. Simulation of storage and retrieval demonstrates that functional associative memory is feasible based on this particular synaptic plasticity. Retrieval reaches a maximum efficiency at a delay of three minutes after storage and is lost after about 9 min. The signal to noise ratio of the retrieved pattern drops steadily as additional associations are stored in memory but retrieval appears to be possible with up to four stored associations. Although the data are derived from synapses not normally proposed as a basis for memory functions, the results here will generalize to other synaptic junctions located more centrally that have similar characteristics. This simulation technique allows the efficiency of associative memory based on various types of synaptic plasticity to be evaluated.     

Devant une OAT idiopathique: Traitement ou assistance médicale à la procréation?

Because poor success obtained with medical treatments in oligo asthenoterato-spermia (OATS) various assisted reproductive techniques (ART) have been successively proposed in these cases. Intra-uterine insemination (IUI) was the first technique to be used, and remains an interesting technique if the indication is correct: abnormal post coital test and semen characteristics no deeply altered; practically: not less than 250.000, or better 500.000 motile sperm after washing and selection of male gametes. Most pregnancies occur during the 3 or 4 first cycles, under ovarian stimulation. In vitro fertilization (IVF) was early proposed in male sterility's, since this system allows to by pass the steps of sperm migration within the female genital tract. The most important study published until now is due to FIVNAT (1995), and concerns 1218 IVF performed with semen characteristics below 500.000 motile and morphologically normal sperm per ml. Conclusions confirm previous data: compared to female indications, cleavage rates and transfer rates per transfer are equivalent. Rates of miscarriages and birth anomalies were not different. This the main difficulty consists in obtaining embryos. Chances of success were logically correlated to semen characteristics; the most discriminant factor was represented by the initial sperm concentration, with a cut-off value equal to 5 millions/ml. Conventional IVF is not indicated in cases of severe alterations of semen characteristics and/or functional sperm disturbances. Various techniques so-called “assisted micro-fertilization techniques” were proposed in order to by pass the different barriers surrounding the oocyte, but one indeed highly superior to all the others: the intracytoplasmic sperm injection (ICSI). Van Steirteghem et al. have recently reported data concerning 2820 ICSI: the fertilization rate was equal to 70%, the proportion of transfers was 91%, with a pregnancy rate equal to 34%. There was to correlation with semen characteristics. The rate of malformations was 2,7% not different of that observed after either natural conception or IVF. Nevertheless, this highly successful technique raises some ethical questions: for example, some abnormal genes, involved in spermatogenesis regulation or not, have not the ability to be transmitted to the next generations.     

Le recalage en imagerie médicale : de la conception à la validation

This paper provides a state of art of medical images registration techniques. We address two important concepts which are the classification of these algorithms and the validation.     

Traçabilité en assistance médicale à la procréation

An ART traceability procedure provides a written record of the controls performed to ensure precise allocation of gametes or embryos during insemination or IVF techniques. This procedure requires analysis of the various steps associated with a risk of error and optimization of safety systems. The author provides a basis for further thought on this subject.     

De la gonorrhée à la blennorragie: Les grandes étapes historiques

This paper examines the history of gonorrhoea and its treatment. It is very probably a very ancient disease that was confused with syphilis for centuries.     

Un estimateur de distributions ajusté pour une aide à la décision de la neutralité génétique des populations

The estimate of the neutrality of a population is often made from a single measurement based on simulations of random patterns. Disputed cases pose a problem regarding the decision-making about the neutrality of the study population. We propose in this paper to provide assistance to the decision of this problem by coupling a genetically neutral populations simulator to a fast adjusted non-parametric estimator of simulated distributions. The choice of the Epanechnikov kernel for the non-parametric method of estimating the kernel allows an analytical approach of the optimal bandwidth, which leads to an improvement in the complexity and therefore a gain in computing time. The fast and reliable estimation of simulated distributions allows to assess the credibility of the decisions about the neutrality of these populations. These results are illustrated by two Tunisian populations whose neutrality is not genetically determined.