Chemical shift encoding (CSE) for sensitive fluorine-19 MRI of perfluorocarbons with complex spectra.

To implement a fluorine-19 ( <sup>19</sup> F) chemical shift encoding (CSE) approach for the sensitive imaging of molecules with multi-resonance spectra to remove their chemical shift displacement (CSD) artifacts, and to characterize its sensitivity versus established pulse sequences. The feasibility of CSE spoiled gradient echo (GRE) and balanced steady-state free precession (bSSFP) was first demonstrated in a phantom study. The dependence of the sensitivity of CSE-bSSFP on several pulse sequence parameters was then established, after which the occurrence of out-of-plane excitation was assessed for 2D and 3D techniques. Next, the sensitivity (in mm <sup>-3</sup> s <sup>-0.5</sup> ) of both CSE techniques was compared to bSSFP ultrashort echo time (bSSFP-UTE) imaging and multi-chemical-shift-selective turbo spin echo (MCSS-TSE) in a second phantom study. Finally, the sensitivity of the CSE-bSSFP, bSSFP-UTE, and MCSS-TSE pulse sequences was compared in a preliminary in vivo mouse study. Both CSE approaches were successfully implemented and resulted in negligible residual CSD artifacts, while large-volume 3D acquisitions should be considered to reduce problems related to out-of-plane excitation. CSE-bSSFP was shown to have a higher sensitivity than the bSSFP-UTE and MCSS-TSE pulse sequences (15.8 ± 1.3 vs. 11.7 ± 1.0 vs. 13.3 ± 0.9 mm <sup>-3</sup> s <sup>-0.5</sup> , respectively, P < 0.001), whereas CSE-GRE technique had a lower sensitivity (4.8 ± 1.1 mm <sup>-3</sup> s <sup>-0.5</sup> ). CSE <sup>19</sup> F MR imaging enables the unambiguous visualization of compounds with complex spectra, and provides high sensitivity both in vitro and in vivo. Magn Reson Med 79:2724-2730, 2018. © 2017 International Society for Magnetic Resonance in Medicine

MR Volumetry of Lung Nodules: A Pilot Study.

Introduction: Computed tomography (CT) is currently the reference modality for the detection and follow-up of pulmonary nodules. While 2D measurements are commonly used in clinical practice to assess growth, increasingly 3D volume measurements are being recommended. The goal of this pilot study was to evaluate preliminarily the capabilities of 3D MRI using ultra-short echo time for lung nodule volumetry, as it would provide a radiation-free modality for this task. Material and Methods: Artificial nodules were manufactured out of Agar and measured using an ultra-short echo time MRI sequence. CT data were also acquired as a reference. Image segmentation was carried out using an algorithm based on signal intensity thresholding (SIT). For comparison purposes, we also performed manual slice by slice segmentation. Volumes obtained with MRI and CT were compared. Finally, the volumetry of a lung nodule was evaluated in one human subject in comparison with CT. Results: Using the SIT technique, minimal bias was observed between CT and MRI across the entire range of volumes (2%) with limits of agreement below 14%. Comparison of manually segmented MRI and CT resulted in a larger bias (8%) and wider limits of agreement (-23% to 40%). In vivo, nodule volume differed of <16% between modalities with the SIT technique. Conclusion: This pilot study showed very good concordance between CT and UTE-MRI to quantify lung nodule volumes, in both a phantom and human setting. Our results enhance the potential of MRI to quantify pulmonary nodule volume with similar performance to CT

Abnormal White Matter Integrity in Adolescents with Internet Addiction Disorder: A Tract-Based Spatial Statistics Study

Background: Internet addiction disorder (IAD) is currently becoming a serious mental health issue around the globe. Previous studies regarding IAD were mainly focused on associated psychological examinations. However, there are few studies on brain structure and function about IAD. In this study, we used diffusion tensor imaging (DTI) to investigate white matter integrity in adolescents with IAD. Methodology/Principal Findings: Seventeen IAD subjects and sixteen healthy controls without IAD participated in this study. Whole brain voxel-wise analysis of fractional anisotropy (FA) was performed by tract-based spatial statistics (TBSS) to localize abnormal white matter regions between groups. TBSS demonstrated that IAD had significantly lower FA than controls throughout the brain, including the orbito-frontal white matter, corpus callosum, cingulum, inferior fronto-occipital fasciculus, and corona radiation, internal and external capsules, while exhibiting no areas of higher FA. Volume-of-interest (VOI) analysis was used to detect changes of diffusivity indices in the regions showing FA abnormalities. In most VOIs, FA reductions were caused by an increase in radial diffusivity while no changes in axial diffusivity. Correlation analysis was performed to assess the relationship between FA and behavioral measures within the IAD group. Significantly negative correlations were found between FA values in the left genu of the corpus callosum and the Screen for Child Anxiety Related Emotional Disorders, and between FA values in the left external capsule and the Young’s Internet addiction scale

Sex counts: An examination of sexual service advertisements in a UK online directory

Internationally, sex work research, public opinion, policy, laws, and practice are predicated on the assumption that commercial sex is a priori sold by women and bought by men. Scarce attention has been devoted to lesbian, gay, bisexual, transgender, or queer/questioning (LGBTQ) sex working as well as women who pay for sex. This is as much an empirical absence as it is a theoretical one, for the ideological claim that women comprise the “vast majority” of sex workers is rarely, if ever, exposed to empirical scrutiny. Focusing on the UK, we address this major gap in evidence in order to challenge the gendered and heterosexist logics that underpin contemporary debates. We do so by presenting large‐scale data gained from the quantitative analysis of 25,511 registered member profiles of an online escort directory. Our findings point to heterogeneity rather than homogeneity in the contemporary sex industry including in terms of gender identity, sexual orientation, and advertised client base. For example, while two‐thirds of advertisements self‐identify as “Female,” one in four are listed as “Male;” less than half list their sexual orientation as “Straight;” and nearly two‐thirds advertise to women clients. Our study thus challenges prevailing heteronormative assumptions about commercial sex, which erase LGBTQ sex workers and other non‐normative identities and practices, and which we argue have important political, practical, and theoretical consequences

Exploring a new method for quantitative sodium MRI in the human upper leg with a surface coil and symmetrically arranged reference phantoms.

The aim of this study is to validate and evaluate the reproducibility of a new setup for the quantification of the tissue sodium concentration (TSC) in the human upper leg muscles with sodium MRI at 3 Tesla. This setup is making use of an emit and receive single loop surface coil together with a set of square, symmetrically arranged reference phantoms. As a second aim, the performances of two MRI protocols for the TSC quantification in the upper leg muscles are compared: one using an ultra-short echo time (UTE) 3-dimensional radial sequence (UTE-protocol), and the other one using standard gradient echo sequence (GRE-protocol). A validation test of the quantification of sodium concentration is performed in phantoms. The bias of the method is estimated and compared between both protocols. The reproducibility of TSC quantification is assessed in phantoms by the coefficient of variation (CV) and compared between both protocols. The reproducibility is also assessed in 11 health volunteers. Signal to noise ratio (SNR) maps are acquired in phantoms with both protocols in order to compare the resulting SNR. The apparatus and post processing were successfully implemented. The bias of the method was smaller than 10% in phantoms (excepted for Na concentration of 10 mmol/L when using the GRE protocol). The reproducibility of the method using symmetrically arranged phantoms was high in phantoms and humans (CV <5%). The GRE-protocol leads to a better SNR than the UTE-protocol in 2D images. The use of symmetrically arranged reference phantoms lead to reproducible results in phantoms and humans. Sodium imaging in the human upper leg with a single loop surface coil should be performed with a standard 2-dimensional GRE protocol if an optimal SNR is needed. However, the quantification of the fast and slow decay time constants of the sodium signal, which plays a role in the TSC quantification, still has to be done with a UTE sequence. Moreover, the quantification of sodium concentration is more accurate with the UTE protocol for small sodium concentrations (<20 mmol)

Classification et clé de détermination des faciès d'écoulements en rivières de montagne

La diversité hydromorphodynamique de 294 faciès d'écoulement appartenant à 15 rivières des Pyrénées a été analysée. A partir d'une Analyse Factorielle des Correspondances Multiples et d'une classification hiérarchique sur les coordonnées des individus, 6 groupes principaux puis 18 sous-groupes de faciès d'écoulement ont pu être différenciés. Une clé de détermination des faciès d'écoulement pour rivière de montagne est proposée. Cinq niveaux de discrimination successifs, quantitatifs ou qualitatifs, permettent d'identifier sur le terrain les 18 sous-groupes de faciès d'écoulement. La validité écologique de cette classification de faciès a été testée sur les biomasses et densités de truites ainsi que sur les densités de frayères. L'appartenance aux 18 sous-groupes explique de 45,6 % de la variabilité des biomasses totales à 18,8 % (p<0.05) de la variabilité des biomasses d'alevins (p<0.05)

Relations entre les caractéristiques de l'habitat et les populations de truites communes (Salmo trutta L.) de la vallée de la Neste d'Aure

Les relations entre les caractéristiques de l'habitat et les biomasses et densités de truites communes (Salmo trutta L.) ont été recherchées dans 33 stations de la rivière Neste d'Aure et trois de ses affluents : la Neste du Louron, la Neste du Rioumajou et le ruisseau d'Espiaube dans le département des Hautes-Pyrénées. L'étude a été conduite sur un cycle annuel. Dans un premier temps, la validité du modèle d'Indice de Qualité d'Habitat (HQI) (BINNS et EISERMAN, 1979), basé sur 10 variables de l'habitat, a été testée. Les biomasses théoriques prévues par le modèle ne sont pas linéairement corrélées aux biomasses observées par pêche électrique. Le meilleur ajustement linéaire est obtenu grâce à des transformations par les logarithmes. Toutefois, la pente de la droite de régression est significativement différente de 1 (t = 2.53(p < 0.01)). Le modèle de l'Indice de Qualité d'Habitat ne constitue pas, dans le cas de la vallée d'Aure, un outil satisfaisant de prévision des biomasses de truites. Dans un deuxième temps, l'influence de chaque variable de l'habitat a été testée individuellement. Les biomasses observées sont significativement corrélées à l'altitude (entre 1350 et 600 m), aux surfaces d'abris, à la température mensuelle maximale (pour une gamme allant de 10 à 16 °C), à la conductivité électrique, à la vitesse moyenne au fond, à la profondeur moyenne et au rapport largeur/profondeur. Les densités sont significativement corrélées aux mêmes variables, à l'exception de la profondeur moyenne ; il faut également ajouter des corrélations significatives avec la pente de la ligne d'eau et la largeur de la rivière. L'étude par classe d'âge montre que l'abondance de la cohorte 0+ est liée à l'altitude, la température et la conductivité. La largeur moyenne constitue la seule caractéristique de l'habitat physique corrélée avec les biomasses et densités de 0+. L'étude par saison indique seulement une corrélation négative entre les densités et biomasses échantillonnées en hiver et la profondeur moyenne. En ce qui concerne la cohorte 1+, on observe des corrélations avec les mêmes variables altitude, température et conductivité auxquelles il faut ajouter la variable abris. Les densités de truites de taille supérieure à la taille légale de capture (180 mm) sont positivement corrélées à la surface d'abris, la profondeur moyenne, la température et la conductivité, et négativement avec l'altitude. Dans une troisième étape, à partir de régressions multiples progressives, il a été possible d'établir un modèle statistique à 5 variables qui explique 86% de la variation de biomasse totale de truites.Ce type d'outil peut constituer un élément de gestion pour les populations de truites de la Vallée de la Neste d'Aure