Double-oblique free-breathing high resolution three-dimensional coronary magnetic resonance angiography.

OBJECTIVES: The goal of the present study was to develop a strategy for three-dimensional (3D) volume acquisition along the major axes of the coronary arteries. BACKGROUND: For high-resolution 3D free-breathing coronary magnetic resonance angiography (MRA), coverage of the coronary artery tree may be limited due to excessive measurement times associated with large volume acquisitions. Planning the 3D volume along the major axis of the coronary vessels may help to overcome such limitations. METHODS: Fifteen healthy adult volunteers and seven patients with X-ray angiographically confirmed coronary artery disease underwent free-breathing navigator-gated and corrected 3D coronary MRA. For an accurate volume targeting of the high resolution scans, a three-point planscan software tool was applied. RESULTS: The average length of contiguously visualized left main and left anterior descending coronary artery was 81.8 +/- 13.9 mm in the healthy volunteers and 76.2 +/- 16.5 mm in the patients (p = NS). For the right coronary artery, a total length of 111.7 +/- 27.7 mm was found in the healthy volunteers and 79.3 +/- 4.6 mm in the patients (p = NS). Comparing coronary MRA and X-ray angiography, a good agreement of anatomy and pathology was found in the patients. CONCLUSIONS: Double-oblique submillimeter free-breathing coronary MRA allows depiction of extensive parts of the native coronary arteries. The results obtained in patients suggest that the method has the potential to be applied in broader prospective multicenter studies where coronary MRA is compared with X-ray angiography.

Mycoplasma hominis in mid-trimester amniotic fluid : relation to pregnangy outcome

RESUME Introduction : Les naissances prématurées compliquent 6-10 % des grossesses dans les pays industrialisés et contribuent de façon notable aux taux de mortalité périnatale et de morbidité néonatale. Il a été démontré que la colonisation bactérienne du liquide amniotique joue un rôle dans l'étiologie des accouchements prématurés spontanés et des ruptures prématurées des membranes. Le but de ce travail était d'évaluer la présence de Mycoplasma hominis dans le liquide amniotique prélevé au 2eme trimestre de grossesse chez des patientes asymptomatiques et de déterminer son association avec une issue défavorable de la grossesse. Matériels et méthodes : Les échantillons de liquide amniotique de 456 patientes ayant subi une amniocentèse trans-abdominale entre les 15eme et I7eme semaines de grossesse pour diverses indications ont été testés par PCR (Polymerase Chain Reaction) afin d'identifier Mycoplasma hominis. Les produits ainsi amplifiés étaient ensuite détectés par ELISA (Enzyme-Linked Immunosorbent Assay). Les données cliniques étaient obtenues après l'accouchement. Résultats : Mycoplasma hominis a été identifié dans 29 (6,4%) des échantillons de liquide amniotique. Le taux de menace d'accouchement prématuré chez les patientes positives pour Mycoplasma hominis (14,3%) était plus élevé que chez les patientes négatives (3,3 %) (p=0,01). De même, les naissances prématurées spontanées avec membranes intactes étaient plus fréquentes chez les patientes positives (10,7%) que chez les patientes négatives (1,9 %) (p=0,02). Le taux de menace d'accouchement prématuré lors d'une grossesse antérieure était plus de trois fois plus élevé chez les patientes positives, cependant ce résultat n'était pas statistiquement significatif. Finalement, la présence du mycoplasme n'était pas corrélée à la gestose, au retard de croissance intra-utérin ou aux anomalies chromosomiques foetales. Conclusions : Les résultats montrent que la présence de Mycoplasma hominis dans le liquide amniotique prélevé entre les 15eme et I7eme semaines d' aménorrhée chez des patientes asymptomatiques est associée à un taux plus élevé de menace d'accouchement prématuré et de naissances prématurées spontanées. La détection de ce microorganisme au 2eme trimestre de la grossesse peut donc identifier les patientes à risque de menace d'accouchement et de naissance prématurées. Abstract Objective: The relationship between detection of Mycoplasma hominis in mid-trimester amniotic fluid and subsequent pregnancy outcome was investigated. Study design: Amniotic fluids from 456 women of European background who underwent a transabdominal amniocentesis at weeks 15-17 of pregnancy were tested for M. hominis by polymerase chain reaction (PCR). The amplicons were hybridized to an internal probe and detected by ELISA. Pregnancy outcomes and clinical data were subsequently obtained. Results: M. hominis were identified in 29 (6.4%) of the amniotic fluids. The rate of preterm labor in women positive for M. hominis (14.3%) was higher than in the negative women (3.3%) (p = 0.01). Similarly, a spontaneous preterm birth with intact membranes occurred in 10.7% of the M. hominis-posltive women as opposed to only 1.9% of the negative women (p = 0.02). The presence of this mycoplasma was not correlated with fetal chromosomal aberrations, intrauterine growth restriction or preeclampsia. Conclusions: Detection of M. hominis in second-trimester amniotic fluids can identify women at increased risk for subsequent preterm labor and delivery.

Rapid detection of enterovirus in cerebrospinal fluid by a fully-automated PCR assay is associated with improved management of aseptic meningitis in adult patients.

BACKGROUND: Enterovirus (EV) is the most frequent cause of aseptic meningitis (AM). Lack of microbiological documentation results in unnecessary antimicrobial therapy and hospitalization. OBJECTIVES: To assess the impact of rapid EV detection in cerebrospinal fluid (CSF) by a fully-automated PCR (GeneXpert EV assay, GXEA) on the management of AM. STUDY DESIGN: Observational study in adult patients with AM. Three groups were analyzed according to EV documentation in CSF: group A=no PCR or negative PCR (n=17), group B=positive real-time PCR (n=20), and group C=positive GXEA (n=22). Clinical, laboratory and health-care costs data were compared. RESULTS: Clinical characteristics were similar in the 3 groups. Median turn-around time of EV PCR decreased from 60h (IQR (interquartile range) 44-87) in group B to 5h (IQR 4-11) in group C (p<0.0001). Median duration of antibiotics was 1 (IQR 0-6), 1 (0-1.9), and 0.5 days (single dose) in groups A, B, and C, respectively (p<0.001). Median length of hospitalization was 4 days (2.5-7.5), 2 (1-3.7), and 0.5 (0.3-0.7), respectively (p<0.001). Median hospitalization costs were $5458 (2676-6274) in group A, $2796 (2062-5726) in group B, and $921 (765-1230) in group C (p<0.0001). CONCLUSIONS: Rapid EV detection in CSF by a fully-automated PCR improves management of AM by significantly reducing antibiotic use, hospitalization length and costs.

Morphometric Analysis of McCoy Cells Inoculated with Cerebrospinal Fluid from Patients with Rabies

To demonstrate the potential of McCoy cells for the isolation of rabies virus from the cerebrospinal (CSF) fluid of a patient with a diagnosis of rabies, McCoy cells were inoculated with CSF from a patient with a clinical diagnosis of rabies and investigated in terms of morphometric aspect using the JAVA analysis system for the quantification of the increased size of infected cells compared to noninfected cells. The cells were also examined in terms of specific staining for the diagnosis of rabies by the method of Sellers for the observation of intracytoplasmic inclusions and by specific immunofluorescence staining for rabies virus. Infected cells showed changes in cell permeability and morphologic modifications which differed significantly compared to normal cells (P<0.001) when analyzed by the Mann-Whitney and Kruskal-Wallis tests. Intense activity of the endoplasmic reticulum was also observed, as indicated by the presence of intracytoplasmic inclusions visualized by specific staining. The present study demonstrated the isolation of rabies virus from the CSF of a patient with rabies, showing that McCoy cells can be used for the laboratory diagnosis of patients suspected to have rabies.

Noninvasive detection of macrophage-rich atherosclerotic plaque in hyperlipidemic rabbits using "positive contrast" magnetic resonance imaging.

OBJECTIVES: This study was designed to identify macrophage-rich atherosclerotic plaque noninvasively by imaging the tissue uptake of long-circulating superparamagnetic nanoparticles with a positive contrast off-resonance imaging sequence (inversion recovery with ON-resonant water suppression [IRON]). BACKGROUND: The sudden rupture of macrophage-rich atherosclerotic plaques can trigger the formation of an occlusive thrombus in coronary vessels, resulting in acute myocardial infarction. Therefore, a noninvasive technique that can identify macrophage-rich plaques and thereby assist with risk stratification of patients with atherosclerosis would be of great potential clinical utility. METHODS: Experiments were conducted on a clinical 3-T magnetic resonance imaging (MRI) scanner in 7 heritable hyperlipidemic and 4 control rabbits. Monocrystalline iron-oxide nanoparticles (MION)-47 were administrated intravenously (2 doses of 250 mumol Fe/kg), and animals underwent serial IRON-MRI before injection of the nanoparticles and serially after 1, 3, and 6 days. RESULTS: After administration of MION-47, a striking signal enhancement was found in areas of plaque only in hyperlipidemic rabbits. The magnitude of enhancement on magnetic resonance images had a high correlation with the number of macrophages determined by histology (p < 0.001) and allowed for the detection of macrophage-rich plaque with high accuracy (area under the curve: 0.92, SE: 0.04, 95% confidence interval: 0.84 to 0.96, p < 0.001). No significant signal enhancement was measured in remote areas without plaque by histology and in control rabbits without atherosclerosis. CONCLUSIONS: Using IRON-MRI in conjunction with superparamagnetic nanoparticles is a promising approach for the noninvasive evaluation of macrophage-rich, vulnerable plaques.

An approximate solution method for boundary layer flow of a power law fluid over a flat plate

The work in this paper deals with the development of momentum and thermal boundary layers when a power law fluid flows over a flat plate. At the plate we impose either constant temperature, constant flux or a Newton cooling condition. The problem is analysed using similarity solutions, integral momentum and energy equations and an approximation technique which is a form of the Heat Balance Integral Method. The fluid properties are assumed to be independent of temperature, hence the momentum equation uncouples from the thermal problem. We first derive the similarity equations for the velocity and present exact solutions for the case where the power law index n = 2. The similarity solutions are used to validate the new approximation method. This new technique is then applied to the thermal boundary layer, where a similarity solution can only be obtained for the case n = 1.

The borehole-fluid effect in electrical resistivity imaging

Fluid that fills boreholes in crosswell electrical resistivity investigations provides the necessary electrical contact between the electrodes and the rock formation but it is also the source of image artifacts in standard inversions that do not account for the effects of the boreholes. The image distortions can be severe for large resistivity contrasts between the rock formation and borehole fluid and for large borehole diameters. We have carried out 3D finite-element modeling using an unstructured-grid approach to quantify the magnitude of borehole effects for different resistivity contrasts, borehole diameters, and electrode configurations. Relatively common resistivity contrasts of 100:1 and borehole diameters of 10 and 20 cm yielded, for a bipole length of 5 m, apparent resistivity underestimates of approximately 12% and 32% when using AB-MN configurations and apparent resistivity overestimates of approximately 24% and 95% when using AM-BN configurations. Effects are generally more severe at shorter bipole spacings. We report the results obtained by either including or ignoring the boreholes in inversions of 3D field data from a test site in Switzerland, where approximately 10,000 crosswell resistivity-tomography measurements were made across six acquisition planes among four boreholes. Inversions of raw data that ignored the boreholes filled with low-resistivity fluid paradoxically produced high-resistivity artifacts around the boreholes. Including correction factors based on the modeling results fora ID model with and without the boreholes did not markedly improve the images. The only satisfactory approach was to use a 3D inversion code that explicitly incorporated the boreholes in the actual inversion. This new approach yielded an electrical resistivity image that was devoid of artifacts around the boreholes and that correlated well with coincident crosswell radar images.

No Role for Cerebrospinal Fluid Myelin Basic Protein Levels in Patients Treated for Childhood Acute Lymphoblastic Leukemia.

INTRODUCTION: Central nervous system prophylaxis of childhood acute lymphoblastic leukemia has dropped rates of relapses but has been associated with neurotoxicity and imaging abnormalities. Predictors of neurotoxicity are lacking, because of inconsistency between clinical symptoms and imaging. Some have suggested that cerebrospinal fluid myelin basic protein (MBP) levels to be of potential interest. A retrospective analysis of MBP levels in correlation with clinical and radiologic data is presented. MATERIALS AND METHODS: MBP levels obtained at the time of intrathecals, charts, and neuroradiology reports were retrospectively analyzed. Academic achievement data were obtained from phone contacts with patients and families. RESULTS: We retrieved 1248 dosages of MBP in 83 patients, 381 neurologic examinations in 34 patients and 69 neuroradiologic investigations in 27 patients. Fifty-two patients had abnormal MBP levels. Radiologic anomalies were present in 47% of those investigated, 14% of them having school difficulties. Proportions of patients with school difficulties in the groups with abnormal MBP levels but no radiologic anomalies or with no radiologic investigations were 0% and 3%, respectively, which was lower than in the group of patients with normal MBP levels (100%, 22%, and 5%, respectively). DISCUSSION: Notwithstanding the retrospective character of our study, we conclude that there is limited usefulness of systematic dosage of MBP as indicator of treatment-induced neurotoxicity in acute lymphoblastic leukemia patients.

Magnetostratigraphy of the Kavaalani section (southwestern Turkey): Consequence for the origin of the Antalya Calcareous Nappes (Turkey) and for the Norian (Late Triassic) magnetic polarity timescale

A magnetostratigraphic study of the Kavaalani section of uppermost Carnian to Upper Norian age, located in the Antalya Calcareous Nappes (southwestern Turkey), reveals nineteen polarity intervals. This pattern correlates very well with two other polarity sequences obtained from the same nappe system (Bolucektasi Tepe and Kavur Tepe) if these sections were deposited in the same (northern) hemisphere. This new interpretation changes our previous conclusions regarding the southern hemisphere origin of the magnetic remanence of the Kavur Tepe section. The paleomagnetic data obtained from the Kavur Tepe and the Kavaalani sections therefore reflect large (similar to 180 degrees) internal rotations within the Antalya nappes. These nappes were likely formed close to the northern tip of the Arabian promontory. We propose a revised yet still preliminary version of the Norian magnetic polarity sequence.

An introduction to model-independent diffusion magnetic resonance imaging.

ABSTRACT: q-Space-based techniques such as diffusion spectrum imaging, q-ball imaging, and their variations have been used extensively in research for their desired capability to delineate complex neuronal architectures such as multiple fiber crossings in each of the image voxels. The purpose of this article was to provide an introduction to the q-space formalism and the principles of basic q-space techniques together with the discussion on the advantages as well as challenges in translating these techniques into the clinical environment. A review of the currently used q-space-based protocols in clinical research is also provided.

Magnetic resonance imaging determinants of intraindividual variability in the elderly: combined analysis of grey and white matter.

Elderly individuals display a rapid age-related increase in intraindividual variability (IIV) of their performances. This phenomenon could reflect subtle changes in frontal lobe integrity. However, structural studies in this field are still missing. To address this issue, we computed an IIV index for a simple reaction time (RT) task and performed magnetic resonance imaging (MRI) including voxel based morphometry (VBM) and the tract based spatial statistics (TBSS) analysis of diffusion tensor imaging (DTI) in 61 adults aged from 22 to 88 years. The age-related IIV increase was associated with decreased fractional anisotropy (FA) as well as increased radial (RD) and mean (MD) diffusion in the main white matter (WM) fiber tracts. In contrast, axial diffusion (AD) and grey matter (GM) densities did not show any significant correlation with IIV. In multivariate models, only FA has an age-independent effect on IIV. These results revealed that WM but not GM changes partly mediated the age-related increase of IIV. They also revealed that the association between WM and IIV could not be only attributed to the damage of frontal lobe circuits but concerned the majority of interhemispheric and intrahemispheric corticocortical connections.

The in vivo performance of magnetic particle-loaded injectable, in situ gelling, carriers for the delivery of local hyperthermia.

We investigated the use of in situ implant formation that incorporates superparamagnetic iron oxide nanoparticles (SPIONs) as a form of minimally invasive treatment of cancer lesions by magnetically induced local hyperthermia. We developed injectable formulations that form gels entrapping magnetic particles into a tumor. We used SPIONs embedded in silica microparticles to favor syringeability and incorporated the highest proportion possible to allow large heating capacities. Hydrogel, single-solvent organogel and cosolvent (low-toxicity hydrophilic solvent) organogel formulations were injected into human cancer tumors xenografted in mice. The thermoreversible hydrogels (poloxamer, chitosan), which accommodated 20% w/v of the magnetic microparticles, proved to be inadequate. Alginate hydrogels, however, incorporated 10% w/v of the magnetic microparticles, and the external gelation led to strong implants localizing to the tumor periphery, whereas internal gelation failed in situ. The organogel formulations, which consisted of precipitating polymers dissolved in single organic solvents, displayed various microstructures. A 8% poly(ethylene-vinyl alcohol) in DMSO containing 40% w/v of magnetic microparticles formed the most suitable implants in terms of tumor casting and heat delivery. Importantly, it is of great clinical interest to develop cosolvent formulations with up to 20% w/v of magnetic microparticles that show reduced toxicity and centered tumor implantation.

Oligo-Miocene extensional tectonics and fluid flow across the Northern Snake Range detachment system, Nevada

The Northern Snake Range (Nevada) represents a spectacular example of a metamorphic core complex and exposes a complete section from the mylonitic footwall into the hanging wall of a fossil detachment system. Paired geochronological and stable isotopic data of mylonitic quartzite within the detachment footwall reveal that ductile deformation and infiltration of meteoric fluids occurred between 27 and 23 Ma. Ar-40/Ar-39 ages display complex recrystallization-cooling relationships but decrease systematically from 26.9 +/- 0.2 Ma at the top to 21.3 +/- 0.2 Ma at the bottom of footwall mylonite. Hydrogen isotope (delta D) values in white mica are very low (-150 to -145 %) within the top 80-90 m of detachment footwall, in contrast to values obtained from the deeper part of the section where values range from -77 to -64 %, suggesting that time-integrated interaction between rock and meteoric fluid was restricted to the uppermost part of the mylonitic footwall. Pervasive mica-water hydrogen isotope exchange is difficult to reconcile with models of Ar-40 loss during mylonitization solely by volume diffusion. Rather, we interpret the Ar-40/Ar-39 ages of white mica with low-delta D values to date syn-mylonitic hydrogen and argon isotope exchange, and we conclude that the hydrothermal system of the Northern Snake Range was active during late Oligocene (27-23 Ma) and has been exhumed by the combined effects of ductile strain, extensional detachment faulting, and erosion.

Low-pressure, water-assisted anatexis of basic dykes in a contact metamorphic aureole, Fuerteventura (Canary Islands): oxygen isotope evidence for a meteoric fluid origin

Migmatites produced by low-pressure anatexis of basic dykes are found in a contact metamorphic aureole around a pyroxenite-gabbro intrusion (PX2), on Fuerteventura. Dykes outside and inside the aureole record interaction with meteoric water, with low or negative delta O-18 whole-rock values (+0.2 to -3.4 parts per thousand), decreasing towards the contact. Recrystallised plagioclase, diopside, biotite and oxides, from within the aureole, show a similar evolution with lowest delta O-18 values (-2.8, -4.2, - 4.4 and -7.6 parts per thousand, respectively) in the migmatite zone, close to the intrusion. Relict clinopyroxene phenocrysts preserved in all dykes, retain typically magmatic delta O-18 values up to the anatectic zone, where the values are lower and more heterogeneous. Low delta O-18 values, decreasing towards the intrusion, can be ascribed to the advection of meteoric water during magma emplacement, with increasing fluid/rock ratios (higher dyke intensities towards the intrusion acting as fluid-pathways) and higher temperatures promoting increasing exchange during recrystallisation.