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Publications (16)24.73 Total impact

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    ABSTRACT: Improved knowledge of brain maturation in fetuses and premature neonates is crucial for the early detection of pathologies and would help determine whether MR data from the premature brain might be used to evaluate fetal maturation. Using diffusion-weighted MR imaging and (1)H-MR spectroscopy, we compared cerebral microstructure and metabolism in normal in utero fetuses imaged near term and premature neonates imaged at term equivalent. Forty-eight subjects were investigated: 24 in utero fetuses (mean gestational age, 37 ± 1 weeks) and 24 premature neonates (mean postconceptional age, 37 ± 1 weeks). ADC values were measured in cerebellum, pons, white matter, brain stem, basal ganglia, and thalamus. MR spectroscopy was performed in deep white matter. Mean ADC values from fetuses and premature neonates were comparable except for the pons and the parietal white matter. ADC values were lower in the pons of premature neonates, whereas greater values were found in their parietal white matter compared with fetuses. Proton MR spectroscopy showed higher levels of NAA/H(2)O, Glx/H(2)O, tCr/H(2)O, and mIns/H(2)O in premature neonates compared with fetuses. Our study provides evidence of subtle anomalies in the parietal white matter of healthy premature neonates. In addition, the reduced ADC values in the pons together with the increased levels of NAA/H(2)O, tCr/H(2)O, and Glx/H(2)O in the centrum semiovale suggest a more advanced maturation in some white matter regions. Our results indicate that MR data from the premature brain are not appropriate for the assessment of the fetal brain maturation.
    American Journal of Neuroradiology 07/2011; 32(8):1451-8. · 3.17 Impact Factor
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    ABSTRACT: To determine the impact of exposing medical students to medical imaging during the first year of the second cycle of medical school (DCEM1) on their perception of this medical specialty and the acquisition of its basic concepts. All students in the 2007-2008 graduation class entering into the first year of the second cycle of medical school were anonymously enrolled into this project that included pre-rotation and post-rotation questionnaires, theory classes followed by clinical rotations with clearly predetermined objectives. A total of 108 students were enrolled, with 70% being females. The parents of the students had a medical or paramedical profession in 46.3% of cases. Before the rotation, 61.6% of students perceived a difference between a hospital-based practice and private practice. Fifty-two percent of students had a clear idea of their professional future prior to the rotation. Five students (4.7%) believed prior to the rotation that it might have an impact on their professional future, versus 63% after the rotation (P<0.0001). The students whose parents work in the medical or paramedical field do not have a better defined idea of their professional future; on the other hand, they have more interest for radiology (73.6% with high or very high interest versus 52.8%, P=0.03). After the rotation, there was a significant increase in the number of students with high or very high interest for radiology (77.8% versus 66.7%, P=0.023). A student noted that he would redirect his career to radiology. There was also a significant increase in the number of students perceiving a difference between a hospital-based practice and private practice (82.2% versus 61.6%, P=0.003). With regards to radiology knowledge before and after the rotation, there was a significant increase of mean scores (P<0.001). Eighty-eight percent of students were satisfied or very satisfied with the radiology rotation. Overall, the students believe that 70% of the objectives were achieved. The only criticism from the students was that the clinical instructors were overworked. Early exposure of medical students to radiology increases their level of interest for the specialty and increases the perception of differences between a hospital-based practice and private practice. The overall knowledge of students about radiology was improved, but the workload of clinical instructors impaired the quality of the rotation.
    Journal de Radiologie 05/2011; 92(5):393-404. · 0.35 Impact Factor
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    ABSTRACT: PurposeTo determine the impact of exposing medical students to medical imaging during the first year of the second cycle of medical school (DCEM1) on their perception of this medical specialty and the acquisition of its basic concepts.
    Journal De Radiologie - J RADIOL. 01/2011; 92(5):393-404.
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    ABSTRACT: The phenotypic heterogeneity of low-grade gliomas (LGGs) is still inconsistently explained by known molecular abnormalities in patients treated according to the present standards of care. IDH1 codon 132 and IDH2 codon 172 sequencing was performed in a series of 47 LGGs and correlated with clinical presentation, MR imaging characteristics, genomic profile and outcome. A total of 38 IDH1 mutations at codon 132 and 2 IDH2 mutations at codon 172 were found, including 35 R132H (87.5%), 2 R132C (5.0%), 1 R132S (2.5%) and 2 R172 M (5%). The IDH mutations were significantly associated with 1p19q deleted genotype (P = 0.031) and p53 expression (P = 0.014). The presence (vs. absence) of IDH mutations was associated with a better outcome (5-year survival rate, 93% vs. 51%, respectively, P = 0.000001). After adjustment for age, tumor location and size, radiologic infiltration pattern and extent of surgery, multivariate analysis confirmed that IDH mutations was an independent favorable prognostic factor (hazard ratio = 40.9; 95% CI, 2.89-578.49, P = 0.006). Furthermore, we showed that patients with IDH-nonmutated tumors were significantly older (P = 0.020) and that these tumors involved significantly more frequently the insula (P = 0.004), were larger in size (>6 cm, P = 0.047), displayed an infiltrative pattern on MRI (P = 0.007) and were all p53 negative with no 1p19q deletion (P < 10⁻⁶). The absence of IDH mutations in LGGs identifies a novel entity of LGGs with distinctive location, infiltrative behavior, specific molecular alterations, and dismal outcome. These findings could significantly modify the LGG classification and may represent a new tool to guide patient-tailored therapy.
    Acta Neuropathologica 11/2010; 120(6):719-29. · 9.73 Impact Factor
  • La Revue de Médecine Interne 10/2010; 31(12):867-71. · 0.90 Impact Factor
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    ABSTRACT: We report a SPECT and PET voxel-based analysis of cerebral blood flow and metabolic rate for glucose in a 23-year-old woman with familial hemiplegic migraine (FHM) caused by ATP1A2 gene mutation. In comparison with healthy subjects, a PET scan showed brain glucose hypometabolism, controlaterally to the hemiplegia, in the perisylvian area early in the attack (Day 1), without any SPECT perfusion abnormalities. Decrease in metabolic rate was only partially reversible at Day 78, concordant at this time with a remaining hemisensory loss. These findings provide further evidence for a primary cortical metabolic dysfunction in FHM.
    Headache The Journal of Head and Face Pain 03/2010; 50(5):872-7. · 2.94 Impact Factor
  • Revue De Medecine Interne - REV MED INTERNE. 01/2010; 31(12):867-871.
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    ABSTRACT: During the last decade, increasing interest in magnetic resonance imaging has emerged for the evaluation of fetal abnormalities detected on ultrasound. The advent of single-shot rapid acquisition sequences has greatly facilitated our ability to obtain detailed imaging information of the fetal brain. To date, fetal magnetic resonance imaging has shown to have an important role in the investigation of cerebral abnormalities suspected by sonography, and in the detection of subtle brain anomalies associated with high-risk pregnancies. Magnetic resonance imaging has proved to be a useful adjunct to sonography during the prenatal period of development, especially for the detection of acquired disorders.
    Seminars in perinatology 09/2009; 33(4):234-50. · 2.33 Impact Factor
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    ABSTRACT: Vigabatrin is an antiepileptic drug that produces intramyelinic edema in several animal models. This study investigates the effect of vigabatrin on the developing human brain. The authors retrospectively blindly review 34 brain magnetic resonance imaging of 22 epileptic infants (age: 9 +/- 1 months) that received vigabatrin, focusing on the presence of hyperintensity on T2- and diffusion-weighted images. Patients treated with vigabatrin displayed significant magnetic resonance imaging hyperintensity of basal ganglia and brain stem (P < .001, Wilcoxon test). This hyperintensity was transient and maximal 3 to 6 months after the beginning of vigabatrin. Hyperintensity was independent from duration and type of epilepsy, and from the presence or absence of seizures. The authors conclude that vigabatrin treatment is associated with transient hypersignal of the basal ganglia and brain stem in epileptic infants. Such transient hyperintensity is likely to be age-dependent and time-dependent because it has never been observed in adult patients.
    Journal of child neurology 03/2009; 24(3):305-15. · 1.59 Impact Factor
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    ABSTRACT: Few studies exist in the literature on pediatric brain tumors examined with advances MRI techniques. The aim of this review is to try to find out some specific tissular characteristics of the main cerebral tumors encountered in children, especially through diffusion imaging, perfusion imaging and proton magnetic resonance spectroscopy (MRS). However, hemispheric cerebral tumors are not as common as in the adult population.
    Journal of Neuroradiology 06/2008; 35(5):261-7. · 1.24 Impact Factor
  • N. Girard, S. Pineau, F. Chapon
    Journal De Radiologie - J RADIOL. 01/2008; 89(10):1319-1319.
  • Journal of Neuroradiology - J NEURORADIOL. 01/2008; 35(5):261-267.
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    ABSTRACT: Magnetic resonance imaging (MRI) is the imaging tool of choice to evaluate brain maturation and especially brain myelination. Magnetic resonance imaging also provides functional insight through diffusion images and proton spectroscopy. In this review the MRI techniques are analyzed for both pre- and postnatal periods. The origin of MR signal changes is also detailed in order to understand normal myelination evolution and the consequences on brain maturation of the different pathologies encountered prior and after birth. Because MRI is "blind" in terms of signal on conventional sequences after 2 years of age, a particular attention is given to diffusion images and proton spectroscopy of the developing brain.
    Journal of Neuroradiology 01/2008; 34(5):290-310. · 1.24 Impact Factor
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    ABSTRACT: Neonatal brain disorders consist of a wide chapter including brain malformations, hypoxic-ischemic encephalopathy (HIE), intracranial infections, perinatal trauma and metabolic encephalopathy. We will focus here on HIE, intracranial infections (especially materno-fetal infection with or without prolonged and/or premature rupture of membranes) and metabolic encephalopathy, those three conditions being the most frequent so far in our experience. Neonatal stroke is also analyzed. Moreover minor perinatal events might be superimposed on an already damaged (infective, edematous, metabolically abnormal or maldeveloped) brain, highlighting the main role and potential benefits of neuroimaging during the neonatal period. The different methods of brain imaging are thus reported with their advantages and disadvantages.
    Journal of Neuroradiology 08/2007; 34(3):167-82. · 1.24 Impact Factor
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    ABSTRACT: La patologia vascolare si avvale di indagini mediante tecniche d’immagine poco o affatto invasive. Gli apparecchi ecoDoppler di ultima generazione migliorati dai mezzi di contrasto ecografici, la risonanza magnetica a banda larga e gli scanner multidetettori sono sufficientemente performanti per poter limitare il ricorso all’angiografia. La scelta dell’esame è condizionata dalla sua affidabilità, dall’indicazione clinica, dalle controindicazioni proprie di ciascun paziente e dal livello tecnico disponibile. L’ecoDoppler viene utilizzato in prima istanza, completato da una RM o da uno scanner a seconda della situazione clinica. In caso di dubbio l’angiografia resta l’ultima spiaggia, ma diventa preponderante soprattutto come guida del trattamento endovascolare. Resta da definire il ruolo della tomografia a emissione di positroni (PET).
    EMC - Tecniche Chirurgiche Vascolare. 12(1):1–22.
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    ABSTRACT: La resonancia magnética (RM) del sistema nervioso fetal, sobre todo del cerebro, juega un papel cada vez más importante en la detección de anomalías del sistema nervioso central, papel favorecido por los adelantos técnicos de la RM y por el desarrollo de centros de diagnóstico prenatal. Todas las técnicas, incluidas las desarrolladas en la población adulta, pueden ser utilizadas para el estudio in utero, aunque con ciertas limitaciones. El conocimiento de las ventajas y los límites de técnicas como la RM, en relación al período posnatal, es primordial para conseguir protocolos de exploración de rutina adaptados a las demandas clínicas y ecográficas, con el objetivo de establecer diagnósticos precoces y permitir el seguimiento uterino de un caso determinado. Todo ello obliga al conocimiento de las modificaciones morfológicas y las características de la RM nuclear (RMN) a lo largo del embarazo. Gracias a estos datos, el conocimiento del sistema nervioso fetal y el diagnóstico de sus anomalías resultan más sencillos.
    EMC - Ginecología-Obstetricia. 44(2):1–13.