La géométrie fractale pour l’analyse de signaux médicaux : état de l’art

The diagnostic interpretation of medical images is a complex task aiming to detect potential abnormalities. One of the most used features in this process is texture which is a key component in the human understanding of images. Many studies were conducted to develop algorithms for texture quantification. The relevance of fractal geometry in medical image analysis is justified by the proven self-similarity of anatomical objects when imaged with a finite resolution. Over the last years, fractal geometry was applied extensively in many medical signal analysis applications. The use of these geometries relies heavily on estimation of the fractal features. Various methods were proposed to estimate the fractal dimension or multifractal spectrum of a signal. This article presents an overview of these algorithms, the way they work, their benefits and limits, and their application in the field of medical signal analysis.     

La part de l’analyse phénoménologique dans l’étude de cas singulier

We argue that clinical psychiatry oscillates between two epistemological poles: inference and perception. The inferential approach categorises illnesses bottom up, from visible symptoms to the pathological category supposedly causing them. In doing so, psychiatry moves away from the possible instantaneous perception of a patient, as well as from illness as a changing, evolving, phenomenon. From a phenomenological point of view, the perceptive approach enables the therapist, within an encounter, to experience the emergence of an impression of a patient’s overall bearing, or attitude. Thanks to épochè, a sense of form, Gestalt will emerge. The clinical case, nevertheless, is always a construction, an intersubjective narrative about illness, recounted by the patient. Creating a library of clinical cases leads to the development of case types, each becoming a reference to which future clinical cases can be compared and categorised as belonging to a clinical family; it is the participant with respect to Plato’s eidos. Phenomenology contributes to clinical experience in that it makes possible the link between perception and inference, between subjective experience and intersubjective narrative, and between person and case type.     

Effets de l’âge et du genre sur la perfusion cérébrale régionale étudiée par deux méthodes d’analyse statistique voxel-par-voxel

Fully automated analysis programs have been applied more and more to aid for the reading of regional cerebral blood flow SPECT study. They are increasingly based on the comparison of the patient study with a normal database. In this study, we evaluate the ability of Three-Dimensional Stereotactic Surface Projection (3D-SSP) to isolate effects of age and gender in a previously studied normal population. The results were also compared with those obtained using Statistical Parametric Mapping (SPM99).MethodsEighty-nine ^99mTc-ECD-SPECT studies performed in carefully screened healthy volunteers (46 females, 43 males; age 20–81 years) were analysed using 3D-SSP. A multivariate analysis based on the general linear model was performed with regions as intrasubject factor, gender as intersubject factor and age as covariate.ResultsBoth age and gender had a significant interaction effect with regional tracer uptake. An age-related decline (p < 0.001) was found in the anterior cingulate gyrus, left frontal association cortex and left insula. Bilateral occipital association and left primary visual cortical uptake showed a significant relative increase with age (p < 0.001). Concerning the gender effect, women showed higher uptake (p < 0.01) in the parietal and right sensorimotor cortices. An age by gender interaction (p < 0.01) was only found in the left medial frontal cortex. The results were consistent with those obtained with SPM99.Conclusion3D-SSP analysis of normal rCBF variability is consistent with the literature and other automated voxel-based techniques, which highlight the effects of both age and gender.     

Étude de l’impact d’une correction d’atténuation par tomodensitométrie en scintigraphie myocardique

Myocardial perfusion SPECT is a routine for the assessment of patients with coronary artery disease (CAD). However, attenuation artifacts may decrease the specificity of the test. These artifacts can be corrected with an attenuation correction. We prospectively included 70 patients who underwent myocardial perfusion SPECT with (IRAC) and without (IRNC) attenuation correction using transmission CT imaging integrated in the acquisition system in patients with low prevalence of CAD. Automatic quantitative analysis with summed stress score (SSS) and rest (SRS) and summed difference score (SDS) was used as interpretation criteria. The results showed a specificity of 80% for IRAC and 56% for IRNC, a positive predictive value of 40% for IRAC and 23% for IRNC, without any significant change in sensitivity. An unpaired t-test showed no significant difference between the overall population and one where an artifact was corrected for heart rate and breath rate during the acquisition effort, the body mass index, chest and abdomen circumferences, and the ratio of these two parameters. Attenuation correction significantly improves the specificity of myocardial scintigraphy with no significant difference in sensitivity. The majority of corrections were for artifacts from the inferior wall in men. There is no correlation between the anthropomorphic and physiological parameters and the occurrence of an artifact of attenuation corrected with CT data.     

Un premier schéma de l’inconscient par Charcot dès 1892

The recent discovery of a drawing of the mind sheds new light on Charcot’s contribution to the discovery of the unconscious. This particular drawing, given by his son Jean-Baptiste, was found in Charcot’s personal notes related to a lecture he gave in June 1892 and was kept in the Salpêtrière historical collection of the University Pierre and Marie Curie. Is this drawing an anticipation of Freud’s first topology of the Unconscious? This is the main issue raised. In order to understand its full meaning, we will focus on Charcot’s scientific thoughts, the specific position he held on hypnosis, his studies on the force of the idea and experimental paralysis, his relationships with Pierre Janet and Sigmund Freud during the years 1885–1992, and finally, his view on Sigmund Freud that is shared in their correspondences.     

À propos de quelques questions éthiques soulevées par la maladie d’Alzheimer

This paper tackles two ethical problems often raised by Alzheimer’s disease and associated disorders: the issue of diagnosis disclosure and the issue of autonomy (or consent). The first part of the paper begins with a critical analysis of the literature on diagnosis disclosure. The authors try to understand why the problem is such a hotly debated issue. They then propose some theoretical and practical perspectives. For example, they suggest that one should allow the patients themselves to designate the persons who should be informed about their health status. They also wonder whether it is really coherent to communicate the diagnosis without discussing its known consequences. The second part of the paper begins with an analytical presentation of the problems one encounters when attempting to respect the autonomy of alzheimer patients. Then the authors discuss the interests and the limits of the proposed solutions to these problems. Finally, they discuss the analyses by two contemporary philosophers (Dworkin and Jaworska) concerning the question: to what extent does Alzheimer’s disease undermine the capacity for autonomy?     

Pré-traitement d’un volume IRM par filtrage anisotrope robuste pour la segmentation de l’épaule

A novel pre-treatment process for image segmentation, based on anisotropic diffusion and robust statistics, is presented in this paper. Image smoothing with edge preservation is shown to help upper limb segmentation (shoulder segmentation in particular) in MRI datasets. The anisotropic diffusion process is mainly controlled by an automated stopping function that depends on the values of voxel gradient. Voxel gradients are divided into two classes: one for high values, corresponding to edge voxels or noisy voxels, one for low values. The anisotropic diffusion process is also controlled by a threshold on voxel gradients that separates both classes. A global estimation of this threshold parameter is classically used. In this paper, we propose a new method based on a local robust estimation. It allows a better removing of noise while preserving edges in the images. An entropy criterion is used to quantify the ability of the algorithm to remove noise with different signal to noise ratios in synthetic images. Another quantitative evaluation criterion based on the Pratt Figure of Merit (FOM) is proposed to evaluate the edge preservation and their location accuracy with respect to a manual segmentation. The results on synthetic and MRI data of shoulder show the assets of the local model in terms of areas homogeneity and edges locations.     

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.     

Le développement de l’inventaire de dépistage ERIraos: un outil global d’appréciation du risque d’évolution psychotique

Adequate identification of patients for early intervention programmes requires reliable and valid assessment tools. Within the German Schizophrenia Network (Kompetenznetz Schizophrenie) a set of schedules for early detection of schizophrenia has been proposed: the Early Recognition Inventory ERIraos. ERIraos is a two-step procedure with a 17-item checklist used at step 1 by GPs, psychologists, teachers, while a comprehensive 110-item symptom list is applied at early intervention centres at the expert level. In addition, ERIraos allows the assessment of several risk factors for psychosis such as familial load, childhood deficiencies, alcohol and drug use by special modules. Some preliminary results are presented here. The frequency of the 17 checklist symptoms increases from the early to the late prodrome, and more specific symptoms occur over time. The 17 checklist symptoms are grouped by factor analysis to 5 factors (psychotic, depressive, disorganised, withdrawn, dysphoric). In addition to prodromal symptoms, most patients (86.2%) report at least one additional risk factor (mean: 1.7 risks). 68% demonstrate some schizotypal features, 53% report alcohol and/or drug consumption, 24% demonstrate some deficiency or delay in childhood development, 21% report definite obstetric or birth complications, and 10% have a family history of schizophrenia or some schizophrenia-like diagnosis in first degree relatives. So far, the results are of a preliminary nature, and when sufficient information on psychotic transitions is available, the predictive value of ERIraos will be determined.     

Les enjeux de l’intégration de l’automate d’immunohématologie AutoVue d’Ortho-Clinical Diagnostics au sein du laboratoire

Evaluation des critères de sécurité, productivité et conformité à la réglementation. L’automatisation de la paillasse d’immuno-hématologie au laboratoire est une démarche dont l’objectif est d’optimiser les contraintes organisationnelles et économiques tout en préservant la qualité des résultats par l’utilisation des techniques analytiques de référence dans un cadre sécuritaire et réglementaire de haut niveau.     

Provenance d’artefacts en rhyolite corse : évaluation des méthodes d’analyse géochimique

Through the analysis of flint and obsidian artefacts, numerous studies have shown the links that existed between Corsica and Sardinia during Neolithic and Chalcolithic. However, we have almost no information about the movements and exchanges that took place in Corsica itself. Rhyolite, a siliceous volcanic rock, has been exploited in Corsica and disseminated throughout the territory from the early Neolithic. Up to now, only one major study has been conducted in the North of the island, in order to identify, by petrographic analysis, the raw material deposits of these rhyolite artefacts. Petrography is a destructive method; it is thus difficult to apply it to large series of archaeological objects. Our aim was therefore to investigate less invasive analytical methods, based on the geochemistry of rocks, in order to conduct future studies based on these rhyolite remains. We analysed 34 geological samples from four different sources, as well as 31 archaeological samples unearthed at three different archaeological areas. We show that EDXRF is an effective method to discriminate sources but also to characterise artefacts using nondestructive protocol. LA-ICP-MS encounters issues due to heterogeneity of the studied rocks. However, we show that by adjusting our testing protocol this method can complement the EDXRF analysis, which is ineffective on objects that are too thin.     

Les théories de l’économie animale et l’émergence de la psychiatrie de l’Encyclopédie à l’aliénisme

The author analysesEncyclopédie’s articles devoted to nervous and mental functioning and disorders, showing that a new approach to lunacy as a mental illness, which is defined in some articles as a “general trouble of the animal economy”, progressively emerged. The term,animal economy, unified physical and moral aspects of the study of man. It was elaborated by XVIIIth century physiologists and was widely accepted by French physicians. This idea is based on the vitalistic thought of the Montpellier school, which equated life with sensibility, and on English medical conceptions of a nervous-centred organism. Later on Philippe Pinel’s work displayed the legacy of these conceptions. On one hand, the comprehensive view of physical and moral dimensions in theanimal economy neutralized the question of an organic or psychogenetic origin of madness. This enabled him to consider it as a determinate field of sensibility interactions and as a medical matter, and to legitimize the group of therapeutic practices that he namedtraitement moral. On the other hand, Pinel departed from the classical conception ofanimal economy by developing his concept of aprinciple of mania, which underlies the manifold symptoms and forms of madness, and which are only perceptible to a trained specialist (aliéniste). The historical development analysed in this article show how alienists were enabled to claim both the wholly medical nature of insanity as disease, and their specific competence as apart from the other medical disciplines. To this extent, Esquirol achieved Pinel’s scientific work.     

Transmission héréditaire de l’information épigénétique par le gamète mâle

What determines phenotype is one of the most fundamental questions in biology. Historically, most studies have focused on genetics but more recent studies have revealed the existence of epigenetic modifications that are not based on DNA sequencing but are essential for appropriate gene expression. Importantly, these epigenetic modifications can be inherited by the offspring. Thus, both male and female gametes contain inherited epigenetic information.     

Profil évolutif de la dénervation cardiaque sympathique dans l’amylose héréditaire à transthyrétine

IntroductionCardiac amyloidosis is a rare disease with poor prognosis, requiring an early diagnosis. I123-MIBG plays an important role in early evaluation of sympathetic cardiac innervation, which is decreased due to amyloid infiltration. The aim of this study was to assess the temporal evolution of cardiac denervation in patients with hereditary amyloidosis, particularly the rate of progression and regional abnormalities; and to identify progression markers.MethodsForty-six patients were included. All of them were carriers of a TTR mutation or received domino liver transplantation, and underwent at least two evaluations of cardiac innervation with MIBG, between February 2011 and February 2018. Progression of cardiac denervation was determined by comparing the H/M ratio at first and final assessment. Regional abnormalities were evaluated using the perfusion/innervation mismatch on a 17 segments model. Logistic regression analysis was used to identify predictors of progression.ResultsTwenty-two patients were stable and 24 were progressive. The mean delay between two MIBG scans was 3.2 ± 1.3 years. Late H/M decreased by 3.9%/year in progressive group, and tended to accelerate after symptoms onset (− 1.4 ± 5.4 vs − 0.49 ± 2.9, P = 0.03). Regional abnormalities were initally located in the infero-latéral segments and extended to the inferior and lateral walls at final assessment. LVEF (OR: 0.90, P = 0.003) and initiation of amyloidosis targeted treatment (OR = 5,35, P = 0.003) were independent predictors of sympathetic denervation progression.ConclusionProgression of myocardial sympathetic denervation in hereditary amyloidosis is slow, but accelerates after symptoms onset. LVEF and treatment are potential progression markers. Regional abnormalities are mainly located in the inferolateral segments and tend to extend at the borders of the denervated area.     

L’analyse combinée de la tomoscintigraphie myocardique de stress et de l’angioscanner coronaire pour identifier les artères responsables de l’ischémie

The identification of ischemia-related coronary artery by stress myocardial perfusion SPECT (SPECT-MPS) is difficult, but it is likely that this identification could be easier by fusionning the SPECT images with images from coronary CT angiography (CTA).ObjectiveTo assess the usefulness of the fusion of SPECT-MPS images with CTA images in the identification of ischemia-related coronary arteries.MethodSPECT-MPS and CTA, which had been recorded in a delay ≤ 3 months, were reanalyzed blindly to identify the coronary arterial vessels with (1) stress ischemia at SPECT-MPS and (2) significant coronary stenosis (> 70 %) at CTA. In case of discordance between the two techniques, an analysis was performed while fusioning the SPECT-MPS and CTA images.ResultsThe population included 38 patients, of whom 22 (58 %) had an ischemia at SPECT-MPS. The identification of the ischemia-related vessels was initially discordant between SPECT-MPS and CTA for 17 patients (45 %). After the fusion's analysis, nine out of these 17 patients (53 %) became totally concordant because of modifications in the CTA analysis in six patients and in the SPECT-MPS analysis in only three. A low severity of ischemia was the main correlate of persisting discordances after fusion: 58 % (7/12) of such low severity ischemia were observed in coronary vessels with persisting discordance, but only 24 % (5/27) with concordant coronary vessels (p = 0.02).ConclusionThe identification with SPECT-MPS of the ischemia-related coronary artery is rarely modified by a fusion analysis with CTA images. Discordances between the two techniques remain frequent, even after fusion, but especially in case of low severity SPECT-MPS ischemias.     

Proposition d’une nouvelle biozonation par ammonites de l’Albien du Bassin andin (Pérou)

The study of the ammonite fauna of the Albian formations allows a major revision of its biostratigraphic frame in northern and central Peru. A carving in ammonite biozones is proposed for the Inca, Chulec and Pariatambo Formations and the Pulluicana group. The Lower Albian is represented by the Nicholsoni Biozone (subdivided into the umbilicostatus, and nicholsoni biohorizons, followed by an interval subzone) and by the Raimondii Biozone (carved in three subzones: Haasi, Raimondii – itself subdivided into the ebrayi and alternum biohorizons – and Mathewsi, including the pseudolyelli biohorizon). The Middle Albian is characterised by the Carbonarium Biozone, carved in the Ulrichi and Carbonarium Subzones. The base of Upper Albian is represented by the Cristatum Subzone.