Intérêt d’une semi-quantification et d’une analyse statistique automatique pour l’interprétation de la tomoscintigraphie cérébrale de perfusion dans la maladie d’Alzheimer

IntroductionAs the visual interpretation of the brain perfusion SPECT for the diagnosis of Alzheimer's disease might be difficult, it is wished to benefit from techniques allowing to improve the diagnostic accuracy especially for the inexperienced readers.Materials and methodsThree readers retrospectively interpreted 77 ^99mTc-ECD SPECT studies within the context of suspected neurodegenerative disease. The probability of Alzheimer's disease was quoted from 1 to 5, and the optimum sensitivity and specificity values were determined from ROC curves. The readers also attributed a hypoperfusion score to 13 brain regions; a diagnosis was obtained from this semi-quantification using a simple logic rule. The SPECT scans were also analyzed using the Planet Neuro software and a diagnosis was reached from a threshold for 2 of the 90 analyzed regions. The gold standard was established by a comprehensive neurological evaluation with at least 5 years of follow-up.ResultsThe sensitivities and specificities of the three readers were 50 %, 56 %, 28 % and 76 %, 83 % and 90 %, respectively. Using the semi-quantification they were 50 %, 67 %, 61 % and 54 %, 85 %, 69 %. The results of two readers were more in agreement. Using the automatic quantification, sensitivity was 78 % and specificity 81 %.ConclusionThe semi-quantification seems to ameliorate the results of and the agreement between certain readers. However, the automatic quantification seems to be the only way of assisting all of the readers to improve their diagnostic performances.     

Scintigraphie cérébrale de perfusion et troubles cognitifs d’origine vasculaire

The vascular cognitive impairment (VCI) is a heterogeneous group of various etiologies, which share a presumed vascular cause. Although the age is the most important risk factor, the cardiovascular risk factors are also involved. A relatively high proportion of these cognitive disorders could be prevented or delayed. Only the treatment of arterial hypertension is recognized as a factor in preventing vascular dementia. MRI is the examination of choice for the investigation of cerebral vascular pathology. However, this morphological imaging is insufficient and does not provide useful functional information. Perfusion brain SPECT is not widely used in the exploration of VCI. Strategies for screening VCI are not standardized and long-term studies are needed to establish the better prevention of cognitive vascular disorders. This article aims to summarize the possible benefit of cerebral perfusion SPECT in the exploration of VCI.     

Effets d’une exposition à la Vinclozoline et à la Génistéine de la gestation à l’âge adulte sur la fonction de reproduction du ratWistar mâle: protocole et résultats préliminaires

Current evidence indicates that endocrine disrupters (EDs) can induce adverse effects on the male reproductive tract in various mammalian species. Recent reports indicate deterioration in male reproductive health in several human populations, but the evidence for a causal link with endocrine disruption is still weak. In addition, the experimental conditions of most of the reportedin vivo studies are not representative of environmental exposures (for example, high doses, short-term exposure, a single ED) and the mechanisms by which EDs disrupt the reproductive system are poorly understood. The objective of the present study is to develop an animal model to assess the reproductive effects and study the putative cellular and molecular mechanisms involved after exposure to genistein (phytoestrogen) and vinclozolin (fungicide with a known antiandrogenic potential) alone or in combination. The study will be performed in male Wistar rats, with administration of low and high doses of the compounds from conception to adulthood and a subset of the males in each treatment group will be mated with unexposed females. We plan to assess the level of sperm production, histology of the reproductive organs, motility and morphometry of spermatozoa and hormone levels, as well as DNA fragmentation of spermatozoa and determination of the number of germ cells, Sertoli cells and the diameters of seminiferous tubules. Estrogen, androgen, progesterone and FSH receptors will be detected and quantified and the level of testicular apoptosis and several apoptosis pathways will be studied to determine the putative cellular and molecular mechanisms involved. The preliminary results confirmed the developmental effects previously reported for high doses of vinclozolin. More interestingly, they indicated a number of deleterious effects for male rats exposed to low dosages alone or mixtures of low and high dosages compared to controls and rats exposed to high dosages alone. For example, a number of developmental anomalies of the genitalia were observed and a significant decrease of sperm motility and motion and fertilizing ability were observed. These preliminary results provide evidence that chronic exposure to environmental levels of EDs or mixtures of EDs have a detrimental impact on the male reproductive tract. The next step involves assessment of the anatomical disorders and the study of some of the cellular and molecular mechanisms possibly involved.     

Effets du rubidium et du césium sur la croissance et la nutrition minerale des characees

Résumé Le rubidium et le césium introduits à l'état de chlorure dans le milieu de culture ont à faible dose un effet stimulant sur la croissance de Chara fragilis et de Chara vulgaris. La résistance de ces végétaux à l'action toxique des deux ions est accrue par l'addition de potassium au milieu.Les analyses chimiques confirment que le rubidium et le césium sont antagonistes vis-à-vis du potassium et du sodium alors qu'ils ne modifient pas de manière significative le taux de calcium.

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Chara fragilis and Chara vulgaris were cultivated in a natural medium containing rubidium and caesium as chloride.The growth of Characeae was increased after culture in the solutions containing Rb and Cs in small amount. The resistance to the toxic effects of these two ions is enhanced if potassium chloride is added to the medium.Quantitative analyses indicate that Rb and Cs decrease the rate of Na and K but have no significative influence on the rate of Ca.

Université de Dijon, Laboratoire de Nutrition minérale des Végétaux     

Aspects cliniques, biologiques et thérapeutiques de la cryptorchidie diagnostiquée à l’âge adulte: analyse d’une série de 69 cas

Objective

To report the clinical, biological and therapeutic features of adult cryptorchidism and to determine whether orchidopexy at adulthood may improve male fertility.

Material and methods

We retrospectively studied the clinical pattern, biological and therapeutic features of 69 men aged of more than 18 years admitted for cryptorchidism at the urological department of Aristide-Le-Dantec teaching hospital between January 1999 and December 2007.

Results

The mean age of our patients was 31.04 ± 8.4 years. In the majority of cases, cryptorchidism was diagnosed in a context of infertility (38 cases), scrotum vacancy (21 cases) and testicular cancer (six cases). Cryptorchidism was unilateral in 69.5% and bilateral in 30.4% of cases. Semen analyses were done for 60 patients and showed azoospermia in 46.6%, oligozoospermia in 38.3% and a normal sperm count in 15% of cases. In all bilateral cryptorchidism cases, semen analyses showed azoospermia. At surgery, the undescended testis was found in 66 cases (95.6%) and orchidopexy was the most done surgical procedure. Seven patients (without testicular cancer) underwent unilateral orchiectomy and histology of specimens showed sertoli-cell-only syndrome with no spermatogenesis in all cases. The histological type of testicular cancer was seminoma (three cases) and embryonic carcinoma (three cases). In azoospermic men (28 cases) no induction of spermatogenesis was achieved after orchidopexy. In infertile patients, the improvement of sperm count was seen in three patients with unilateral cryptorchidism. Three patients with unilateral crytorchidism achieved pregnancy (pregnancy rate of 7.8%).

Conclusion

Orchidopexy for adult cryptorcidism had little impact in male fertility. Because of the risk of testicular cancer, orchidectomy was recommended as treatment of unilateral cryptorchidism. But with the recent development of TESE, orchidopexy appears as a reasonable treatment of adult cryptorchidism.     

Cryptorchidie: influence sur la fertilité de l’âge au moment de l’orchidopexie, du siège et de la taille du testicule et de l’existence d’anomalies épididymaires

Despite surgical treatment, cryptorchidism is the most common cause of infertility. Through a literature review, the authors report current data on the influence of age at the time of orchidopexy, testicular size, the position of the testis, and the existence of epididymal anomalies on fertility.     

Influence du positionnement du patient sur la survenue des artefacts et l’interprétation des images de perfusion myocardique obtenues à partir d’une caméra dédiée à semi-conducteurs CZT

Myocardial perfusion imaging (MPI) can be affected by physical artefacts, such as attenuation and Compton scatter, both related to patient's morphological characteristics and his/her position during acquisition. These positional artefacts have been largely studied with classical Anger cameras. Recently, a new generation of heart-dedicated cameras has emerged, using novel cadmium–zinc–telluride (CZT) semi-conductors, with different physical characteristics and geometrical distribution. Our study aimed to investigate, in this new generation camera, the relation between patient's positioning and the occurring of physical artefacts. Plus, we examined whether these artefacts were likely to affect the interpretation made with such images.Material and methodsIn this prospective study, we included 60 patients scheduled in our unit for MPI. All of them underwent both prone and supine acquisitions, after stress test as well as at rest.ResultsAt a global population level, we observed significantly more abnormalities in supine acquisitions in territories mainly vascularized by right coronary artery, and to a lesser extent, by circumflex artery, than observed in prone acquisitions. No scoring difference was observed, regardless of position, in Summed Stress Score, Summed Rest Score or Summed Difference Score. This observation remained the same whether on a global population level, or on a BMI- and perimeter-basis level.ConclusionPosition related physical artefacts, such as attenuation and Compton scattering, are similar to those previously described with Anger cameras. These artefacts do not affect the interpretation of myocardial scans significantly, provided that both images are acquired in the same anatomical position.     

Effets de l’Oxygenation du Milieu d’Incubation des Cotyledons de Ricin sur les Flux de Protons et sur l’Absorption du Saccharose

Some of the effects of oxygen concentration in the external medium bathing castor bean cotyledons were investigated. At 700 μM O₂, the sucrose-dependent proton influx was dependent on external pH while sucrose influx was independent of pH between 4,5 and 6; proton influx and sucrose influx were both dependent on external sucrose concentration; both were saturated above 50 mM sucrose. The stoichiometry H+/S decreased with increasing pH and sucrose concentration. These data were consistent with the results obtained in stirred or aerated external medium. Oxygen consumption, acidification of the medium, sucrose-dependent proton influx and sucrose uptake increased with increasing oxygen concentration up to 700 μM where saturation was reached. Bubbling with air (O₂, 160 μM) resulted in the same increase despite lower oxygen concentration. It is suggested that not only O₂ concentration but also CO₂ concentration act on O₂ consumption, and proton and sucrose fluxes.

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Effets de la fluorescence résiduelle dans les tissus biologiques sur les signaux de fluorescence résolus temporellement par la méthode des éléments finis

A computational model based on finite element method is derived to examine how the simulated time-dependent signals are related to the presence of residual fluorescence in biological media surrounding a fluorescent object. We apply a subtraction technique on recorded data when imperfect uptake of fluorescing agent into the tumor is considered. We show the limits of the subtracting method for low target: background fluorescent absorption contrast by extracting the time to reach the half maximum and analyzing the maximum of the time-resolved signals versus target depth.     

Évaluation de l’exactitude de latéralisation du foyer épileptogène par la tomographie par émission de positons au 18f-fluorodésoxyglucose dans le bilan préopératoire de l’épilepsie temporale : analyse visuelle simple et par index d’asymétrie inter-hémisphérique par soustraction d’images,analyse quantitative par statistical parametric mapping

IntroductionInter-ictal 18F-2-fluoro-deoxy-D-glucose-positron emission tomography (FDG-PET) plays a key role for the preoperative evaluation of patients with pharmacoresistant temporal lobe epilepsy. PET images are usually analyzed visually, a way that is reported to provide a high diagnostic value but that remains subjective, depending on the expertise and experience of the observer. By contrast, the voxel-based quantitative analyses, such as statistical parametric mapping (SPM), are objective and therefore, observer independent methods of analyses. In this study, the accuracy of the analyses of brain FDG-PET images to lateralize the temporal lobe epileptogenic zone was compared between: (1) a conventional visual method, (2) a quantitative SPM analysis, and (3) a visual analysis of inter-hemispheric asymmetry (IHA) obtained after images substraction.Materials and methodsFDG-PET scans of 31 patients presenting a severe temporal epilepsy and whom the temporal foci had been accurately lateralized (successful subsequent surgical treatment) were retrospectively analysed by (1) a consensual visual analysis from two experienced observers; (2) SPM analysis with voxel-wise comparisons of FDG-PET images of patients with those of age-matched healthy controls, using various statistical threshold (P) and cluster (k) values; and (3) visual assessment by the two same observers of images obtained for assessing the IHA. For this purpose, a flipped image was initially obtained by reversing in the left-right direction the FDG-PET images, which had been previously spacially normalized with the SPM template. Then, flipped and non-flipped images were substracted.ResultsThe temporal hypometabolic area was accurately identified: (1) by the conventional visual analysis in 87 % of patients and with a satisfactory interobserver reproducibility (interobserver Cohen's coefficient = 0.79); (2) by SPM analysis, in 90 % of patients (when using optimal thresholds of 0.01 for P value and of 50 voxels (400 mm³) for k value); and (3) with the visual analysis of IHA in 97 % of patients with an excellent interobserver reproductibility (interobserver Cohen's coefficient = 1).ConclusionIn patients presenting severe temporal epilepsy, visual assessment of FDG-PET images from IHA seems more accurate for lateralizing the epileptogenic temporal areas when compared with either conventional visual or quantitative SPM analyses. Moreover, this method is very easy to use in clinical practice, contrary to the quantitative method using SPM