Central and Cortical Gray Mater Segmentation of Magnetic Resonance Images of the Fetal Brain

Motivation. The study of human brain development in itsearly stage is today possible thanks to in vivo fetalmagnetic resonance imaging (MRI) techniques. Aquantitative analysis of fetal cortical surfacerepresents a new approach which can be used as a markerof the cerebral maturation (as gyration) and also forstudying central nervous system pathologies [1]. However,this quantitative approach is a major challenge forseveral reasons. First, movement of the fetus inside theamniotic cavity requires very fast MRI sequences tominimize motion artifacts, resulting in a poor spatialresolution and/or lower SNR. Second, due to the ongoingmyelination and cortical maturation, the appearance ofthe developing brain differs very much from thehomogenous tissue types found in adults. Third, due tolow resolution, fetal MR images considerably suffer ofpartial volume (PV) effect, sometimes in large areas.Today extensive efforts are made to deal with thereconstruction of high resolution 3D fetal volumes[2,3,4] to cope with intra-volume motion and low SNR.However, few studies exist related to the automatedsegmentation of MR fetal imaging. [5] and [6] work on thesegmentation of specific areas of the fetal brain such asposterior fossa, brainstem or germinal matrix. Firstattempt for automated brain tissue segmentation has beenpresented in [7] and in our previous work [8]. Bothmethods apply the Expectation-Maximization Markov RandomField (EM-MRF) framework but contrary to [7] we do notneed from any anatomical atlas prior. Data set &Methods. Prenatal MR imaging was performed with a 1-Tsystem (GE Medical Systems, Milwaukee) using single shotfast spin echo (ssFSE) sequences (TR 7000 ms, TE 180 ms,FOV 40 x 40 cm, slice thickness 5.4mm, in plane spatialresolution 1.09mm). Each fetus has 6 axial volumes(around 15 slices per volume), each of them acquired inabout 1 min. Each volume is shifted by 1 mm with respectto the previous one. Gestational age (GA) ranges from 29to 32 weeks. Mother is under sedation. Each volume ismanually segmented to extract fetal brain fromsurrounding maternal tissues. Then, in-homogeneityintensity correction is performed using [9] and linearintensity normalization is performed to have intensityvalues that range from 0 to 255. Note that due tointra-tissue variability of developing brain someintensity variability still remains. For each fetus, ahigh spatial resolution image of isotropic voxel size of1.09 mm is created applying [2] and using B-splines forthe scattered data interpolation [10] (see Fig. 1). Then,basal ganglia (BS) segmentation is performed on thissuper reconstructed volume. Active contour framework witha Level Set (LS) implementation is used. Our LS follows aslightly different formulation from well-known Chan-Vese[11] formulation. In our case, the LS evolves forcing themean of the inside of the curve to be the mean intensityof basal ganglia. Moreover, we add local spatial priorthrough a probabilistic map created by fitting anellipsoid onto the basal ganglia region. Some userinteraction is needed to set the mean intensity of BG(green dots in Fig. 2) and the initial fitting points forthe probabilistic prior map (blue points in Fig. 2). Oncebasal ganglia are removed from the image, brain tissuesegmentation is performed as described in [8]. Results.The case study presented here has 29 weeks of GA. Thehigh resolution reconstructed volume is presented in Fig.1. The steps of BG segmentation are shown in Fig. 2.Overlap in comparison with manual segmentation isquantified by the Dice similarity index (DSI) equal to0.829 (values above 0.7 are considered a very goodagreement). Such BG segmentation has been applied on 3other subjects ranging for 29 to 32 GA and the DSI hasbeen of 0.856, 0.794 and 0.785. Our segmentation of theinner (red and blue contours) and outer cortical surface(green contour) is presented in Fig. 3. Finally, torefine the results we include our WM segmentation in theFreesurfer software [12] and some manual corrections toobtain Fig.4. Discussion. Precise cortical surfaceextraction of fetal brain is needed for quantitativestudies of early human brain development. Our workcombines the well known statistical classificationframework with the active contour segmentation forcentral gray mater extraction. A main advantage of thepresented procedure for fetal brain surface extraction isthat we do not include any spatial prior coming fromanatomical atlases. The results presented here arepreliminary but promising. Our efforts are now in testingsuch approach on a wider range of gestational ages thatwe will include in the final version of this work andstudying as well its generalization to different scannersand different type of MRI sequences. References. [1]Guibaud, Prenatal Diagnosis 29(4) (2009). [2] Rousseau,Acad. Rad. 13(9), 2006, [3] Jiang, IEEE TMI 2007. [4]Warfield IADB, MICCAI 2009. [5] Claude, IEEE Trans. Bio.Eng. 51(4) (2004). [6] Habas, MICCAI (Pt. 1) 2008. [7]Bertelsen, ISMRM 2009 [8] Bach Cuadra, IADB, MICCAI 2009.[9] Styner, IEEE TMI 19(39 (2000). [10] Lee, IEEE Trans.Visual. And Comp. Graph. 3(3), 1997, [11] Chan, IEEETrans. Img. Proc, 10(2), 2001 [12] Freesurfer,http://surfer.nmr.mgh.harvard.edu.

4-7-19, stade Pershing, [Lawrence] Shields, Américain, à l'arrivée de la course de relais de 3000 m [des Jeux interalliés, le n°835 William C. Gray, membre du relais américain, lève le poing en signe de victoire] : [photographie de presse] / [Agence Rol]

Référence bibliographique : Rol, 54716

Anti-aging : Una relectura contemporània de Dorian Gray

Partint de l'estudi del llibre El retrat de Dorian Gray d'Oscar Wilde s'analitzarà, des del punt de vista de la cultura actual, una societat que s'aferra a la joventut i utilitza tots els mètodes tecnològics per defugir de la vellesa.

Unwanted sexual experiences among adolescents: shedding light on the gray zone between consensual and non-consensual sex.

This study aimed at exploring adolescents' perceptions of unwanted sexual experiences (USE) in order to set up definitions, categories, and boundaries on the continuum between consensual and non-consensual sex. METHODS: We conducted a qualitative thematic analysis of four focus group discussions gathering a total of 29 male and female adolescents aged 16-20 years. RESULTS: Analysis of participants' discourse revealed three main characteristics that define USE, namely, regret, as most situations discussed were said to be acceptable or not in terms of whether there were regrets after the fact; misperception of sexual intent; and lack of communication between partners. CONCLUSIONS: Our findings revealed that health professionals should be aware of the subtle aspects identifying USE when screening for situations that can have adverse psychological consequences. Where prevention is concerned, it appears important to address these aspects of USE in sex education classes.

Uma nova espécie de Cladomorphus Gray, 1835 (Phasmatidae, Cladomorphinae) de Minas Gerais, Brasil

Cladomorphus trimariensis sp. nov. é descrita de Três Marias, Minas Gerais. A nova espécie difere de C. phyllinus Gray, 1835 principalmente pelo opérculo e placa micropilar do ovo, ausência de espinhos nas pernas médias e posteriores e pelas projeções distais nos tergos IV e V, que são menos desenvolvidas.

Proton T1 relaxation times of metabolites in human occipital white and gray matter at 7 T.

Proton T1 relaxation times of metabolites in the human brain have not previously been published at 7 T. In this study, T1 values of CH3 and CH2 group of N-acetylaspartate and total creatine as well as nine other brain metabolites were measured in occipital white matter and gray matter at 7 T using an inversion-recovery technique combined with a newly implemented semi-adiabatic spin-echo full-intensity acquired localized spectroscopy sequence (echo time = 12 ms). The mean T1 values of metabolites in occipital white matter and gray matter ranged from 0.9 to 2.2 s. Among them, the T1 of glutathione, scyllo-inositol, taurine, phosphorylethanolamine, and N-acetylaspartylglutamate were determined for the first time in the human brain. Significant differences in T1 between white matter and gray matter were found for water (-28%), total choline (-14%), N-acetylaspartylglutamate (-29%), N-acetylaspartate (+4%), and glutamate (+8%). An increasing trend in T1 was observed when compared with previously reported values of N-acetylaspartate (CH3 ), total creatine (CH3 ), and total choline at 3 T. However, for N-acetylaspartate (CH3 ), total creatine, and total choline, no substantial differences compared to previously reported values at 9.4 T were discernible. The T1 values reported here will be useful for the quantification of metabolites and signal-to-noise optimization in human brain at 7 T. Magn Reson Med 69:931-936, 2013. © 2012 Wiley Periodicals, Inc.

Evaluación poblacional de Gari solida (Gray, 1828) en bahía Independencia-Pisco, junio 2010

En junio 2010, se efectuó la evaluación poblacional de almeja Gari solida en los principales bancos naturales de bahía Independencia: El Ancla, Pan de Azúcar y La Pampa para determinar su distribución, concentración, estructura por tamaños y magnitud poblacional. Los resultados evidenciaron una disminución de la biomasa y población, respecto a agosto del 2008, en 44,9% y 56,2%, respectivamente. La densidad por unidad de muestreo fluctuó entre 1 y 47 ind.m-2, las mayores densidades medias se encontraron en Pan de Azúcar (5,06 ind.m-2), La Pampa (2,42 ind.m-2) y menor densidad en El Ancla (0,57 ind.m-2). La biomasa total se calculó en 336,96 t (± 19,9%) y la población en 8,48 millones de individuos (± 19,85%), el 22,1% de la biomasa correspondió a ejemplares con tamaño mínimo de extracción (TME ≥75 mm). Las tallas de 792 ejemplares analizados fluctuaron entre 4 y 95 mm de longitud valvar, con moda en 65 mm y media en 57,5 mm. El rendimiento promedio del pie con respecto al peso total fue de 1: 9,5.

Gray Hungarian Partridge, 2011

Data sheet produced by the Iowa Department of Natural Resources is about different times of animals, insects, snakes, birds, fish, butterflies, etc. that can be found in Iowa.

Cuando Frankenstein encontró a Dorian Gray: dandysmo, post-identidad y sujetos virtuales

The appearance and popularization of the internet has created new forms of writing, which compel us to think anew about identity and subjectivity. Webjournals or blogs are specially interesting because they are a massive phenomenon that use autobiographical writing in a peculiar way. These forms of writing stress a particular paradox of the genre: the coexistence between a purpose of private, confessional and spontaneous writing and a public image, carefully built, as a result of its writing. The technology is new, but, in fact, the paradox is old. This paper tries to explore this old paradox, our eternal condition of cyborgs, our use of technologies in order to construct a public, unique and recognizably identity. In oder to do so, I will try to show the virtual condition of any written individual ¿this issue has already been dealt with by autobiographical studies¿, focusing on blogs, and especially on concrete example (Lord Whimsy¿s Journal). I will pay attention to gender as a technology that constructs identity and, at the same time, is deconstructed by the autobiographical narratives analyzed. In short, I attempt to show that virtual and autobiographical discourse do not bring forth a new kind of subject but the permanence of an old phenomenon "clearly developed by dandyism, for instance¿: the use of tehnologies to re-invent, re-formulate and re-construct us as multiple, hybrid and mixed subjects."

Taxonomy of the genus Chamaesyce S.F. Gray in the Iberian Peninsula and the Balearic Islands

A taxonomic study is undertaken of the ten taxa (nine of them specific) belonging to the genus Chamaesyce S.F. Gray (Euphorbiaceae) which are present in the Iberian Peninsula and the Balearic Islands and a dichotomic key is provided. The taxonomic chacarcteristics of ecology are given. The presence of Chamaesyce humifusa (Willd.) Prokh. in the Iberian Peninsula is confirmed and Chamaesyce humistrata (Gray) Small is recorded for the first time from Europe.

A proposito de los generos Aconitum L. y Consolida (DC.) S.F.Gray en la Peninsula Iberica.

Seguimos para este taxon, en lo nomenclatural, a TAMURA & LAUENER (1979:459), mientras no se tipifique de forma adecuada A. lycoctonum L., considerado nom. ambig. ya por TUTIN (1964:212), con pocas posibilidades de que no sea diverso de A. vulparia. A. pyrenaicum L. es también algo muy distinto del taxon que nos ocupa y, en caso de no ser aceptada la proposición de que se lo considere ñamen rejiciendum, hecha por TAMURA & LAUENER (Le.: 447), seria el nombre correcto para A. barbatum Pers. (=A. squarrosum DC.) de Siberia. Otro nombre que aún podría ser prioritario, A. altissimum Miller (WARNCKE, 1964:30; TAMURA & LAUENER, l.c), no puede usarse en tanto no se localice algún material de aquel en que se basó la descripción un tanto ambigua de Miller....

Notas corologicas balearicas de Chamaesyce S.F. Gray

Con el fin de allegar materiales para un estudio cariológico de Chamaesyce S. F. Gray que forma parte de una revisión genérica, objeto de la tesis de licenciatura de uno de nosotros J. J. Orell , se planteó la necesidad de visitar la isla de Mallorca. Fruto de la visita son las notas que siguen.

Cuando Frankenstein encontró a Dorian Gray: dandysmo, post-identidad y sujetos virtuales

The appearance and popularization of the internet has created new forms of writing, which compel us to think anew about identity and subjectivity. Webjournals or blogs are specially interesting because they are a massive phenomenon that use autobiographical writing in a peculiar way. These forms of writing stress a particular paradox of the genre: the coexistence between a purpose of private, confessional and spontaneous writing and a public image, carefully built, as a result of its writing. The technology is new, but, in fact, the paradox is old. This paper tries to explore this old paradox, our eternal condition of cyborgs, our use of technologies in order to construct a public, unique and recognizably identity. In oder to do so, I will try to show the virtual condition of any written individual ¿this issue has already been dealt with by autobiographical studies¿, focusing on blogs, and especially on concrete example (Lord Whimsy¿s Journal). I will pay attention to gender as a technology that constructs identity and, at the same time, is deconstructed by the autobiographical narratives analyzed. In short, I attempt to show that virtual and autobiographical discourse do not bring forth a new kind of subject but the permanence of an old phenomenon "clearly developed by dandyism, for instance¿: the use of tehnologies to re-invent, re-formulate and re-construct us as multiple, hybrid and mixed subjects."