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https://www.readbyqxmd.com/read/28646593/mri-assisted-dual-motion-correction-for-myocardial-perfusion-defect-detection-in-pet-imaging
#1
Xinhui Wang, Arman Rahmim, Jing Tang
PURPOSE: Myocardial perfusion (MP) PET imaging is a powerful tool in risk assess-assessment and stratification of patients with coronary artery disease. Involuntary organmotion degrades cardiac PET image resolution while respiratory and/or cardiac gating to freeze the motion leads to noisier reconstructed images due to reduced counts in the gated frames. In this work, we propose an MRI assisted dual motion correction method to compensate for respiratory and cardiac motion in MP PET data and study the impact of dual motion correction on MP defect detection using systematically designed experiments...
June 24, 2017: Medical Physics
https://www.readbyqxmd.com/read/28646146/optical-coherence-microscopy-as-a-novel-non-invasive-method-for-the-4d-live-imaging-of-early-mammalian-embryos
#2
Karol Karnowski, Anna Ajduk, Bartosz Wieloch, Szymon Tamborski, Krzysztof Krawiec, Maciej Wojtkowski, Maciej Szkulmowski
Imaging of living cells based on traditional fluorescence and confocal laser scanning microscopy has delivered an enormous amount of information critical for understanding biological processes in single cells. However, the requirement for a high numerical aperture and fluorescent markers still limits researchers' ability to visualize the cellular architecture without causing short- and long-term photodamage. Optical coherence microscopy (OCM) is a promising alternative that circumvents the technical limitations of fluorescence imaging techniques and provides unique access to fundamental aspects of early embryonic development, without the requirement for sample pre-processing or labeling...
June 23, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28645326/improving-visualization-of-4d-flow-cardiovascular-magnetic-resonance-with-four-dimensional-angiographic-data-generation-of-a-4d-phase-contrast-magnetic-resonance-cardioangiography-4d-pc-mrca
#3
Mariana Bustamante, Vikas Gupta, Carl-Johan Carlhäll, Tino Ebbers
Magnetic Resonance Angiography (MRA) and Phase-Contrast MRA (PC-MRA) approaches used for assessment of cardiovascular morphology typically result in data containing information from the entire cardiac cycle combined into one 2D or 3D image. Information specific to each timeframe of the cardiac cycle is, however, lost in this process. This study proposes a novel technique, called Phase-Contrast Magnetic Resonance CardioAngiography (4D PC-MRCA), that utilizes the full potential of 4D Flow CMR when generating temporally resolved PC-MRA data to improve visualization of the heart and major vessels throughout the cardiac cycle...
June 23, 2017: Journal of Cardiovascular Magnetic Resonance
https://www.readbyqxmd.com/read/28645293/prenatal-screening-of-fetal-ventriculoarterial-connections-benefits-of-4d-technique-in-fetal-heart-imaging
#4
Yu Wang, Miao Fan, Faiza Amber Siddiqui, Meilian Wang, Wei Sun, Xue Sun, Wenjia Lei, Ying Zhang
BACKGROUND: Identification of prenatal ventriculoarterial connections in fetuses with conotruncal anomalies (CTA) remains one of the greatest challenges for sonographers performing screening examinations. Herein, we propose a novel protocol of 4D volume analysis that identifies ventriculoarterial connections and evaluate its clinical utility in routine screenings. METHODS: Twenty-nine cases of transposition of the great arteries (TGA), 22 cases of double-outlet right ventricle (DORV), 36 cases of tetralogy of Fallot (TOF), 14 cases of truncus arteriosus (TCA), and randomly selected 70 normal fetuses were reviewed in this study...
June 23, 2017: Cardiovascular Ultrasound
https://www.readbyqxmd.com/read/28644661/soft-photon-and-graviton-theorems-in-effective-field-theory
#5
Henriette Elvang, Callum R T Jones, Stephen G Naculich
Extensions of the photon and graviton soft theorems are derived in 4D local effective field theories with massless particles of arbitrary spin. We prove that effective operators can result in new terms in the soft theorems at subleading order for photons and subsubleading order for gravitons. The new soft terms are unique, and we provide a complete classification of all local operators responsible for such modifications. We show that no local operators can modify the subleading soft graviton theorem. The soft limits are taken in a manifestly on-locus manner using a complex double deformation of the external momenta...
June 9, 2017: Physical Review Letters
https://www.readbyqxmd.com/read/28644511/bacteriophage-tail-tube-assembly-studied-by-proton-detected-4d-solid-state-nmr
#6
Maximilian Zinke, Pascal Fricke, Camille Samson, Songhwan Hwang, Joseph Wall, Sascha Lange, Sophie Zinn-Justin, Adam Lange
Obtaining unambiguous resonance assignments remains a major bottleneck in solid-state NMR studies of protein structure and dynamics. Particularly for supramolecular assemblies with large subunits (>150 residues), the analysis of crowded spectral data presents a challenge, even if three-dimensional (3D) spectra are used. Here, we present a proton-detected 4D solid-state NMR assignment procedure that is tailored for large assemblies. The key to recording 4D spectra with three indirect carbon or nitrogen dimensions with their inherently large chemical shift dispersion lies in the use of sparse non-uniform sampling (as low as 2%)...
June 23, 2017: Angewandte Chemie
https://www.readbyqxmd.com/read/28644151/ecg-based-4d-dose-reconstruction-of-cardiac-arrhythmia-ablation-with-carbon-ion-beams-application-in-a-porcine-model
#7
Daniel Richter, H Immo Lehmann, Anna Eichhorn, Anna M Constantinescu, Robert Kaderka, Matthias Prall, Patrick Lugenbiel, Mitsuru Takami, Dierk Thomas, Christoph Bert, Marco Durante, Douglas L Packer, Christian Graeff
Noninvasive ablation of cardiac arrhythmia by scanned particle radiotherapy is highly promising, but especially challenging due to cardiac and respiratory motion. Irradiations for catheter-free ablation in intact pigs were carried out at the GSI Helmholtz Center in Darmstadt using scanned carbon ions. Here, we present real-time electrocardiogram (ECG) data to estimate time-resolved (4D) delivered dose. For 11 animals, surface ECGs and temporal structure of beam delivery were acquired during irradiation. R waves were automatically detected from surface ECGs...
June 23, 2017: Physics in Medicine and Biology
https://www.readbyqxmd.com/read/28643924/exosomes-novel-regulators-of-bone-remodelling-and-potential-therapeutic-agents-for-orthodontics
#8
REVIEW
L S Holliday, K P McHugh, J Zuo, J I Aguirre, J K Neubert, W J Rody
Recent studies suggest that exosomes are involved in intercellular communication required for the maintenance of healthy bone. Exosomes are small (30-150 nm in diameter) extracellular vesicles that are formed in multivesicular bodies and are released from cells as the multivesicular bodies fuse with the plasma membrane. Regulatory exosomes have the capacity to exert profound control over target cells. They can stimulate plasma membrane receptors and are also internalized by the target cell delivering proteins, lipids, small molecules and functional RNAs from the cell of origin...
June 2017: Orthodontics & Craniofacial Research
https://www.readbyqxmd.com/read/28642891/safety-tolerability-of-the-anti-semaphorin-4d-antibody-vx15-2503-in-a-randomized-phase-1-trial
#9
Christopher LaGanke, Lawrence Samkoff, Keith Edwards, Lily Jung Henson, Pavle Repovic, Sharon Lynch, Lael Stone, David Mattson, Aaron Galluzzi, Terrence L Fisher, Christine Reilly, Laurie A Winter, John E Leonard, Maurice Zauderer
OBJECTIVE: To evaluate the safety, tolerability, pharmacokinetics (PK), and pharmacodynamics (PD) of VX15/2503 in a randomized, single-dose, dose-escalation, double-blind, placebo-controlled study enrolling adult patients with MS. METHODS: Single IV doses of VX15/2503 or placebo were administered. Ten patients each were randomized (4:1 randomization ratio) into 5 ascending dose cohorts of 1, 3, 6, 10, or 20 mg/kg. Safety, immunogenicity, PK/PD, MRI, ECG, and lymphocyte subset levels were evaluated...
July 2017: Neurology® Neuroimmunology & Neuroinflammation
https://www.readbyqxmd.com/read/28640394/in-scan-and-scan-rescan-assessment-of-lv-in-and-outflow-volumes-by-4d-flow-mri-versus-2d-planimetry
#10
Vivian P Kamphuis, Roel L F van der Palen, Patrick J H de Koning, Mohammed S M Elbaz, Rob J van der Geest, Albert de Roos, Arno A W Roest, Jos J M Westenberg
PURPOSE: To evaluate the in-scan and scan-rescan consistency of left ventricular (LV) in- and outflow assessment from 1) 2D planimetry; 2) 4D flow magnetic resonance imaging (MRI) with retrospective valve tracking, and 3) 4D flow MRI with particle tracing. MATERIALS AND METHODS: Ten healthy volunteers (age 27 ± 3 years) underwent multislice cine short-axis planimetry and whole-heart 4D flow MRI on a 3T MRI scanner twice with repositioning between the scans...
June 22, 2017: Journal of Magnetic Resonance Imaging: JMRI
https://www.readbyqxmd.com/read/28638413/uterine-cavity-abnormalities-in-patients-with-endometriosis-in-alexandria-a-diagnostic-test-accuracy-study
#11
Eman Aly Abd El Fattah
Endometriosis is strongly associated with infertility. Endometrial polyps are prevalent in infertile women and they have similar pathological characteristics to endometriosis, suggesting a possible association. Uterine malformations as uterine septum and hypoplastic uterus are also linked to endometriosis. Hysterosalpingogram and transvaginal ultrasonography are used to diagnose endometrial lesions. Hysteroscopy can detect small lesions that might be missed. Recently, 4D ultrasonography is being used, but which is superior has not been established yet...
2017: Obstetrics and Gynecology International
https://www.readbyqxmd.com/read/28637308/three-dimensional-right-ventricular-regional-deformation-and-survival-in-pulmonary-hypertension
#12
Pamela Moceri, Nicolas Duchateau, Delphine Baudouy, Elie-Dan Schouver, Sylvie Leroy, Fabien Squara, Emile Ferrari, Maxime Sermesant
Aims: Survival in pulmonary hypertension (PH) relates to right ventricular (RV) function. However, the RV unique anatomy and structure limit 2D analysis and its regional 3D function has not been studied yet. The aim of this study was to assess the implications of global and regional 3D RV deformation on clinical condition and survival in adults with PH and healthy controls. Methods and results: We collected a prospective longitudinal cohort of 104 consecutive PH patients and 34 healthy controls between September 2014 and December 2015...
June 15, 2017: European Heart Journal Cardiovascular Imaging
https://www.readbyqxmd.com/read/28636002/electronic-structure-and-time-dependent-description-of-rotational-predissociation-of-lih
#13
P Jasik, J E Sienkiewicz, J Domsta, N E Henriksen
The adiabatic potential energy curves of the (1)Σ(+) and (1)Π states of the LiH molecule were calculated. They correlate asymptotically to atomic states, such as 2s + 1s, 2p + 1s, 3s + 1s, 3p + 1s, 3d + 1s, 4s + 1s, 4p + 1s and 4d + 1s. A very good agreement was found between our calculated spectroscopic parameters and the experimental ones. The dynamics of the rotational predissociation process of the 1(1)Π state were studied by solving the time-dependent Schrödinger equation. The classical experiment of Velasco [Can...
June 21, 2017: Physical Chemistry Chemical Physics: PCCP
https://www.readbyqxmd.com/read/28635959/optogenetic-activation-of-plexin-b1-reveals-contact-repulsion-between-osteoclasts-and-osteoblasts
#14
Abhijit Deb Roy, Taofei Yin, Shilpa Choudhary, Vladimir Rodionov, Carol C Pilbeam, Yi I Wu
During bone remodelling, osteoclasts induce chemotaxis of osteoblasts and yet maintain spatial segregation. We show that osteoclasts express the repulsive guidance factor Semaphorin 4D and induce contact inhibition of locomotion (CIL) in osteoblasts through its receptor Plexin-B1. To examine causality and elucidate how localized Plexin-B1 stimulation may spatiotemporally coordinate its downstream targets in guiding cell migration, we develop an optogenetic tool for Plexin-B1 designated optoPlexin. Precise optoPlexin activation at the leading edge of migrating osteoblasts readily induces local retraction and, unexpectedly, distal protrusions to steer cells away...
June 21, 2017: Nature Communications
https://www.readbyqxmd.com/read/28635614/advanced-treatment-planning-using-direct-4d-optimisation-for-pencil-beam-scanned-particle-therapy
#15
Kinga Bernatowicz, Ye Zhang, Rosalind Lucy Perrin, Damien Charles Weber, Antony John Lomax
We report on development of a new four-dimensional (4D) optimisation approach for scanned proton beams, which incorporates both irregular motion patterns and the delivery dynamics of the treatment machine into the plan optimiser. Furthermore, we assess the effectiveness of this technique to reduce dose to critical structures in proximity to moving targets, while maintaining effective target dose homogeneity and coverage. The proposed approach has been tested using both a simulated phantom and a clinical liver cancer case, and allows for realistic 4D calculations and optimisation using irregular breathing patterns extracted from e...
June 21, 2017: Physics in Medicine and Biology
https://www.readbyqxmd.com/read/28634788/consistent-reconstruction-of-4d-fetal-heart-ultrasound-images-to-cope-with-fetal-motion
#16
Christine Tanner, Barbara Flach, Céline Eggenberger, Oliver Mattausch, Michael Bajka, Orcun Goksel
PURPOSE: 4D ultrasound imaging of the fetal heart relies on reconstructions from B-mode images. In the presence of fetal motion, current approaches suffer from artifacts, which are unrecoverable for single sweeps. METHODS: We propose to use many sweeps and exploit the resulting redundancy to automatically recover from motion by reconstructing a 4D image which is consistent in phase, space, and time. An interactive visualization framework to view animated ultrasound slices from 4D reconstructions on arbitrary planes was developed using a magnetically tracked mock probe...
June 20, 2017: International Journal of Computer Assisted Radiology and Surgery
https://www.readbyqxmd.com/read/28629434/reduction-of-breathing-irregularity-related-motion-artifacts-in-low-pitch-spiral-4d-ct-by-optimized-projection-binning
#17
René Werner, Christian Hofmann, Eike Mücke, Tobias Gauer
BACKGROUND: Respiration-correlated CT (4D CT) is the basis of radiotherapy treatment planning of thoracic and abdominal tumors. Current clinical 4D CT images suffer, however, from artifacts due to unfulfilled assumptions concerning breathing pattern regularity. We propose and evaluate modifications to existing low-pitch spiral 4D CT reconstruction protocols to counteract respective artifacts. METHODS: The proposed advanced reconstruction (AR) approach consists of two steps that build on each other: (1) statistical analysis of the breathing signal recorded during CT data acquisition and extraction of a patient-specific reference breathing cycle for projection binning; (2) incorporation of an artifact measure into the reconstruction...
June 19, 2017: Radiation Oncology
https://www.readbyqxmd.com/read/28627499/first-principles-studies-of-chromium-line-ordered-alloys-in-a-molybdenum-disulfide-monolayer
#18
Noeliarinala Felana Andriambelaza, Edwin Mapasha, Nithaya Chetty
Density functional theory (DFT) calculations have been performed to study the thermodynamic stability, structural and electronic properties of various chromium (Cr) line-ordered alloy configurations in a molybdenum disulfide (MoS<sub>2</sub>) hexagonal monolayer for band gap engineering. Only the molybdenum (Mo) sites were substituted at each concentration in this study. For comparison purpose, different Cr line-ordered alloy and random alloy configurations were studied and the most thermodynamically stable ones at each concentration were identified...
June 19, 2017: Journal of Physics. Condensed Matter: An Institute of Physics Journal
https://www.readbyqxmd.com/read/28625908/-on-the-spot-the-use-of-4d-cta-to-differentiate-a-true-spot-sign-from-a-distal-intracranial-aneurysm
#19
Johanna P de Jong, Leo Kluijtmans, Martinus J van Amerongen, Mathias Prokop, Hieronymus D Boogaarts, Frederick J A Meijer
BACKGROUND: Spontaneous intracerebral hemorrhage may arise from underlying abnormalities including aneurysms. Computed tomography angiography (CTA) is widely used for the detection of possible underlying causes, which is important since it may have immediate therapeutic consequences. In addition, CTA is used to detect the so-called "spot sign", indicating active hemorrhage which carries a worse prognosis. CTA is, however, a snapshot in time. Four-dimensional CTA (4D-CTA) is a dynamic type of imaging and has emerged as a valuable imaging technique for different neurovascular disorders...
June 15, 2017: World Neurosurgery
https://www.readbyqxmd.com/read/28624916/interethnic-variation-in-pelvic-floor-morphology-in-women-with-symptomatic-pelvic-organ-prolapse
#20
Zeelha Abdool, Hans Peter Dietz, Barend Gerhardus Lindeque
INTRODUCTION AND HYPOTHESIS: There is a lack of epidemiological studies evaluating female pelvic organ prolapse in developing countries. Current studies have largely focused on women of white ethnicity. This study was designed to determine interethnic variation in pelvic floor functional anatomy, namely, levator hiatal distensibility and pelvic organ descent, in women with symptomatic pelvic organ prolapse in a multi-ethnic South African population. METHODS: This prospective observational study included 258 consecutive women referred for pelvic organ prolapse assessment and management at a tertiary urogynaecological clinic...
June 17, 2017: International Urogynecology Journal
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