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Functional MR

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https://www.readbyqxmd.com/read/29793061/microstructural-imaging-of-the-human-brain-with-a-super-scanner-10-key-advantages-of-ultra-strong-gradients-for-diffusion-mri
#1
D K Jones, D C Alexander, R Bowtell, M Cercignani, F Dell'Acqua, D J McHugh, K L Miller, M Palombo, G J M Parker, U S Rudrapatna, C M W Tax
The key component of a microstructural diffusion MRI 'super-scanner' is a dedicated high-strength gradient system that enables stronger diffusion weightings per unit time compared to conventional gradient designs. This can, in turn, drastically shorten the time needed for diffusion encoding, increase the signal-to-noise ratio, and facilitate measurements at shorter diffusion times. This review, written from the perspective of the National Facility for In Vivo MR Imaging of Human Tissue Microstructure, an initiative to establish a shared 300 mT/m-gradient facility amongst the microstructural imaging community, describes ten advantages of ultra-strong gradients for microstructural imaging...
May 21, 2018: NeuroImage
https://www.readbyqxmd.com/read/29791905/disparities-in-chronic-kidney-disease-prevalence-among-males-and-females-in-195-countries-analysis-of-the-global-burden-of-disease-2016-study
#2
Boris Bikbov, Norberto Perico, Giuseppe Remuzzi
BACKGROUND: Chronic kidney disease (CKD) imposes a substantial burden on health care systems. There are some especially vulnerable groups with a high CKD burden, one of which is women. We performed an analysis of gender disparities in the prevalence of all CKD stages and renal replacement therapy (defined as impaired kidney function [IKF]) in 195 countries. METHODS: We used estimates produced by the Global Burden of Disease (GBD) Study 2016 revision using a Bayesian-regression analytic tool, DisMoD-MR 2...
May 23, 2018: Nephron
https://www.readbyqxmd.com/read/29790857/attenuation-correction-for-brain-pet-imaging-using-deep-neural-network-based-on-dixon-and-zte-mr-images
#3
Kuang Gong, Jaewon Yang, Kyungsang Kim, Georges El Fakhri, Youngho Seo, Quanzheng Li
Positron Emission Tomography (PET) is a functional imaging modality widely used in neuroscience studies. To obtain meaningful quantitative results from PET images, attenuation correction is necessary during image reconstruction. For PET/MR hybrid systems, PET attenuation is challenging as Magnetic Resonance (MR) images do not reflect attenuation coefficients directly. To address this issue, we present deep neural network methods to derive the continuous attenuation coefficients for brain PET imaging from MR images...
May 23, 2018: Physics in Medicine and Biology
https://www.readbyqxmd.com/read/29790820/towards-quantitative-18f-fdg-pet-mri-of-the-brain-automated-mr-driven-calculation-of-an-image-derived-input-function-for-the-non-invasive-determination-of-cerebral-glucose-metabolic-rates
#4
Lalith Ks Sundar, Otto Muzik, Lucas Rischka, Andreas Hahn, Ivo Rausch, Rupert Lanzenberger, Marius Hienert, Eva-Maria Klebermass, Frank-Günther Füchsel, Marcus Hacker, Magdalena Pilz, Ekaterina Pataraia, Tatjana Traub-Weidinger, Thomas Beyer
Absolute quantification of PET brain imaging requires the measurement of an arterial input function (AIF), typically obtained invasively via an arterial cannulation. We present an approach to automatically calculate an image-derived input function (IDIF) and cerebral metabolic rates of glucose (CMRGlc) from the [18F]FDG PET data using an integrated PET/MRI system. Ten healthy controls underwent test-retest dynamic [18F]FDG-PET/MRI examinations. The imaging protocol consisted of a 60-min PET list-mode acquisition together with a time-of-flight MR angiography scan for segmenting the carotid arteries and intermittent MR navigators to monitor subject movement...
January 1, 2018: Journal of Cerebral Blood Flow and Metabolism
https://www.readbyqxmd.com/read/29789551/epidermal-glucocorticoid-and-mineralocorticoid-receptors-act-cooperatively-to-regulate-epidermal-development-and-counteract-skin-inflammation
#5
Judit Bigas, Lisa M Sevilla, Elena Carceller, Julia Boix, Paloma Pérez
Endogenous and synthetic glucocorticoids (GCs) regulate epidermal development and combat skin inflammatory diseases. GC actions can be mediated through the GC receptor (GR) and/or the mineralocorticoid receptor (MR), highly homologous ligand-activated transcription factors. While the role of GR as a potent anti-inflammatory mediator is well known, that of MR is not as clear, nor is whether these receptors cooperate or antagonize each other in the epidermis. To address this, we generated mice with epidermal-specific loss of both receptors (double knockout, DKO), and analyzed the phenotypical and functional consequences relative to single KOs or controls (CO)...
May 22, 2018: Cell Death & Disease
https://www.readbyqxmd.com/read/29788278/prognostic-value-of-left-ventricular-reverse-remodelling-and-recurrent-mitral-regurgitation-after-personalized-surgical-treatment-of-patients-with-non-ischaemic-cardiomyopathy-and-functional-mitral-regurgitation
#6
Annelieke H J Petrus, Laurens F Tops, Eva Timmer, Michel I M Versteegh, Olaf M Dekkers, Robert J M Klautz, Jerry Braun
OBJECTIVES: The aim of this study was to determine the prevalence of left ventricular reverse remodelling (LVRR) and recurrent mitral regurgitation (MR) at mid-term follow-up (1-2 years after surgery) in patients after personalized surgical treatment of heart failure and functional MR due to non-ischaemic cardiomyopathy and to assess their prognostic impact on long-term clinical outcomes. METHODS: Consecutive patients with refractory heart failure and non-ischaemic MR, who underwent mitral valve surgery with or without additional procedures, were identified...
May 19, 2018: Interactive Cardiovascular and Thoracic Surgery
https://www.readbyqxmd.com/read/29787866/handedness-dependent-functional-organizational-patterns-within-the-bilateral-vestibular-cortical-network-revealed-by-fmri-connectivity-based-parcellation
#7
V Kirsch, R Boegle, D Keeser, E Kierig, B Ertl-Wagner, T Brandt, M Dieterich
Current evidence points towards a vestibular cortex that involves a multisensory bilateral temporo-parietal-insular network with a handedness-dependent hemispheric lateralization. This study aimed to identify handedness-dependent organizational patterns of (lateralized and non-lateralized) functional subunits within the human vestibular cortex areas. 60 healthy volunteers (30 left-handed and 30 right-handed) were examined on a 3T MR scanner using resting state functional MRI (fMRI). The data was analyzed in four major steps using a functional connectivity based parcellation (fCBP) approach: (1) independent component analysis (ICA) on a whole brain level to identify different resting state networks (RSN); (2) creation of a vestibular informed mask from four whole brain ICs that included reference coordinates of the vestibular network extracted from meta-analyses of vestibular neuroimaging experiments; (3) Re-ICA confined to the vestibular informed mask; (4) cross-correlation of the activated voxels within the vestibular subunits (parcels) to each other (P-to-P) and to the whole-brain RSN (P-to-RSN)...
May 19, 2018: NeuroImage
https://www.readbyqxmd.com/read/29786715/cancer-cell-membrane-coated-magnetic-nanoparticles-for-mr-nir-fluorescence-dual-modal-imaging-and-photodynamic-therapy
#8
Jiong Li, Xuandong Wang, Dongye Zheng, Xinyi Lin, Zuwu Wei, Da Zhang, Zhuanfang Li, Yun Zhang, Ming Wu, Xiaolong Liu
Theranostic nanoprobes integrated with dual-modal imaging and therapeutic functions, such as photodynamic therapy (PDT), have exhibited significant potency in cancer treatments due to their high imaging accuracy and non-invasive advantages for cancer elimination. However, biocompatibility and highly efficient accumulation of these nanoprobes in tumor are still unsatisfactory for clinical application. In this study, a photosensitizer -loaded magnetic nanobead with surface further coated with a layer of cancer cell membrane (SSAP-Ce6@CCM) was designed to improve the biocompatibility and cellular uptake and ultimately achieve enhanced MR/NIR fluorescence imaging and PDT efficacy...
May 22, 2018: Biomaterials Science
https://www.readbyqxmd.com/read/29786487/diffusion-weighted-mri-is-superior-to-pet-ct-in-predicting-survival-of-patients-undergoing-90-y-radioembolization-of-hepatic-metastases
#9
Alexandra Barabasch, Alexander Heinzel, Philipp Bruners, Nils A Kraemer, Christiane K Kuhl
Purpose To determine the relationship between diffusion-weighted (DW) liver MR images obtained 4-6 weeks after lobar yttrium 90 (90 Y) treatment and overall survival in comparison with PET/CT or established oncologic factors known to affect survival. Materials and Methods The institutional review board approved this prospective intraindividual comparative study in 36 consecutive patients (25 women) with liver-dominant metastases (20 colorectal, 14 breast, two other) (mean age, 60 years ± 10 [standard deviation]) who underwent fluorine 18 (18 F) fluorodeoxyglucose (FDG) PET/CT and DW MRI before and 4-6 weeks after 90 Y radioembolization...
May 21, 2018: Radiology
https://www.readbyqxmd.com/read/29783201/n-4-18-f-fluorobenzyl-cholylglycine-a-novel-tracer-for-pet-of-enterohepatic-circulation-of-bile-acids-radiosynthesis-and-proof-of-concept-studies-in-rats
#10
Kim Frisch, Damion H R Stimson, Taracad Venkatachalam, Gregory K Pierens, Susanne Keiding, David Reutens, Rajiv Bhalla
INTRODUCTION: Enterohepatic circulation (EHC) of conjugated bile acids is an important physiological process crucial for regulation of intracellular concentrations of bile acids and their function as detergents and signal carriers. Only few bile acid-derived imaging agents have been synthesized and hitherto none have been evaluated for studies of EHC. We hypothesized that N-(4-[18 F]fluorobenzyl)cholylglycine ([18 F]FBCGly), a novel fluorine-18 labeled derivative of endogenous cholylglycine, would be a suitable tracer for PET of the EHC of conjugated bile acids, and we report here a radiosynthesis of [18 F]FBCGly and a proof-of-concept study by PET/MR in rats...
May 4, 2018: Nuclear Medicine and Biology
https://www.readbyqxmd.com/read/29782653/data-driven-gating-in-pet-influence-of-respiratory-signal-noise-on-motion-resolution
#11
Florian Büther, Iris Ernst, Lynn Johann Frohwein, Joost Pouw, Klaus Peter Schäfers, Lars Stegger
PURPOSE: Data-driven gating (DDG) approaches for positron emission tomography (PET) are interesting alternatives to conventional hardware-based gating methods. In DDG, the measured PET data themselves are utilized to calculate a respiratory signal that is subsequently used for gating purposes. The success of gating is then highly dependent on the statistical quality of the PET data. In this study we investigate how this quality determines signal noise and thus motion resolution in clinical PET scans using a center-of-mass-based (COM) DDG approach, specifically with regard to motion management of target structures in future radiotherapy planning applications...
May 21, 2018: Medical Physics
https://www.readbyqxmd.com/read/29779258/hyperpolarized-porous-silicon-nanoparticles-potential-theragnostic-material-for-%C3%A2-%C3%A2-si-magnetic-resonance-imaging
#12
Hyeonglim Seo, Ikjang Choi, Nicholas Whiting, Jingzhe Hu, Quy Son Luu, Shivanand Pudakalakatti, Caitlin McCowan, Yaewon Kim, Niki Zacharias, Seunghyun Lee, Pratip Bhattacharya, Youngbok Lee
Porous silicon nanoparticles have recently garnered attention as potentially-promising biomedical platforms for drug delivery and medical diagnostics. Here, we demonstrate porous silicon nanoparticles as contrast agents for ²⁹Si magnetic resonance imaging. Size-controlled porous silicon nanoparticles were synthesized by magnesiothermic reduction of silica nanoparticles and were surface activated for further functionalization. Particles were hyperpolarized via dynamic nuclear polarization to enhance their ²⁹Si MR signals; the particles demonstrated long ²⁹Si spin-lattice relaxation (T₁) times (~ 25 mins), which suggests potential applicability for medical imaging...
May 20, 2018: Chemphyschem: a European Journal of Chemical Physics and Physical Chemistry
https://www.readbyqxmd.com/read/29778855/myocardial-strain-in-prediction-of-outcomes-after-surgery-for-severe-mitral-regurgitation
#13
Hyue Mee Kim, Goo-Yeong Cho, In-Chang Hwang, Hong-Mi Choi, Jun-Bean Park, Yeonyee E Yoon, Hyung-Kwan Kim
OBJECTIVES: We investigated whether global longitudinal strain (GLS) is a better predictor of clinical events after surgery for mitral regurgitation (MR) than conventional parameters. BACKGROUND: The optimal timing for surgery is guided by left ventricular (LV) dimension or left ventricular ejection fraction (LVEF), even though normal LVEF can mask depressed LV systolic function in severe mitral MR. METHODS: From 2006 to 2016, 506 patients (age 58...
May 11, 2018: JACC. Cardiovascular Imaging
https://www.readbyqxmd.com/read/29777670/the-impact-of-mitral-disease-etiology-on-operative-mortality-following-mitral-valve-operations
#14
J Scott Rankin, Maria Grau-Sepulveda, David M Shahian, A Marc Gillinov, Rakesh Suri, James S Gammie, Steven F Bolling, Patrick M McCarthy, Vinod H Thourani, Niv Ad, Sean M O'Brien, Jeffrey P Jacobs, Vinay Badhwar
BACKGROUND: The patho-etiology of mitral regurgitation (MR) has been suggested as a mediator of outcomes following mitral valve (MV) operations, particularly in ischemic functional mitral regurgitation (IMR). This study examined the independent association of MV etiology with mortality. METHODS: Using the Society of Thoracic Surgeons Database, all patients undergoing mitral valve replacement or repair from 2011-2014 were assessed. Patients who underwent concomitant surgical ablation, septal defect closure, tricuspid valve repair, or coronary artery bypass grafting were included...
May 16, 2018: Annals of Thoracic Surgery
https://www.readbyqxmd.com/read/29776996/effects-of-chronic-exposure-to-12%C3%A2-saltwater-on-the-endocrine-physiology-of-juvenile-american-alligator-alligator-mississippiensis
#15
P C Faulkner, M L Burleson, L Simonitis, C Marshall, D Hala, L H Petersen
American alligator ( Alligator mississippiensis , Linnaeus) habitats are prone to saltwater intrusion following major storms, hurricanes or droughts. Anthropogenic impacts affecting hydrology of freshwater systems may exacerbate saltwater intrusion into freshwater habitats. The endocrine system of alligators is susceptible to changes in the environment but it is currently not known how the crocodilian physiological system responds to environmental stressors such as salinity. Juvenile alligators were exposed to 12‰ saltwater for 5 weeks to determine effects of chronic exposure to saline environments...
May 18, 2018: Journal of Experimental Biology
https://www.readbyqxmd.com/read/29772066/3d-specific-absorption-rate-estimation-from-high-intensity-focused-ultrasound-sonications-using-the-green-s-function-heat-kernel
#16
Nicholas J Freeman, Henrik Odéen, Dennis L Parker
PURPOSE: Evaluate a numerical inverse Green's function method of deriving specific absorption rates (SARs) from high intensity focused ultrasound (HIFU) sonications given tissue parameters (thermal conductivity, specific heat capacity, and mass density) and 3-D magnetic resonance imaging (MRI) temperature measurements. METHODS: SAR estimates were evaluated using simulations and MR temperature measurements from HIFU sonications. For simulations, a "true" SAR was calculated using the hybrid angular spectrum method for ultrasound simulations...
May 17, 2018: Medical Physics
https://www.readbyqxmd.com/read/29770490/functional-magnetic-resonance-electrical-impedance-tomography-fmreit-sensitivity-analysis-using-an-active-bidomain-finite-element-model-of-neural-tissue
#17
Rosalind J Sadleir, Fanrui Fu, Munish Chauhan
PURPOSE: A direct method of imaging neural activity was simulated to determine typical signal sizes. METHODS: An active bidomain finite-element model was used to estimate approximate perturbations in MR phase data as a result of neural tissue activity, and when an external MR electrical impedance tomography imaging current was added to the region containing neural current sources. RESULTS: Modeling-predicted, activity-related conductivity changes should produce measurable differential phase signals in practical MR electrical impedance tomography experiments conducted at moderate resolution at noise levels typical of high field systems...
May 16, 2018: Magnetic Resonance in Medicine: Official Journal of the Society of Magnetic Resonance in Medicine
https://www.readbyqxmd.com/read/29765606/a-new-mr-sad-algorithm-for-the-automatic-building-of-protein-models-from-low-resolution-x-ray-data-and-a-poor-starting-model
#18
Pavol Skubák, Demet Araç, Matthew W Bowler, Ana R Correia, Andre Hoelz, Sine Larsen, Gordon A Leonard, Andrew A McCarthy, Sean McSweeney, Christoph Mueller-Dieckmann, Harm Otten, Gabriel Salzman, Navraj S Pannu
Determining macromolecular structures from X-ray data with resolution worse than 3 Å remains a challenge. Even if a related starting model is available, its incompleteness or its bias together with a low observation-to-parameter ratio can render the process unsuccessful or very time-consuming. Yet, many biologically important macromolecules, especially large macromolecular assemblies, membrane proteins and receptors, tend to provide crystals that diffract to low resolution. A new algorithm to tackle this problem is presented that uses a multivariate function to simultaneously exploit information from both an initial partial model and low-resolution single-wavelength anomalous diffraction data...
March 1, 2018: IUCrJ
https://www.readbyqxmd.com/read/29762931/mitraclip-technique-five-years-after-alfieri-stitch-mitral-valve-repair
#19
Ivaylo R Tonchev, Anna Turyan, Ronen Beeri, Mony Shuvy
The case is described of a successful MitraClip procedure performed on an 88-year-old patient with severe mitral regurgitation (MR), five years after she had undergone mitral valve repair using the Alfieri surgical procedure. It is suggested that the MitraClip procedure is an option in patients with severe MR persisting after the Alfieri procedure. Video 1: Transesophageal echocardiography before the MitraClip procedure. Severe mitral regurgitation with preserved left ventricular systolic function. The main regurgitant jet originates from the medial commissure...
September 2017: Journal of Heart Valve Disease
https://www.readbyqxmd.com/read/29762924/early-improvement-in-mitral-regurgitation-after-cardiac-resynchronization-therapy-in-cardiomyopathy-patients
#20
Hakimeh Sadeghian, Masoumeh Lotfi-Tokaldany, Mahdi Montazeri, Ali Kazemi Saeed, Mohammad Sahebjam, Akram Sardari, Gita Ejmalian
BACKGROUND: The study aim was to investigate factors affecting the improvement of mitral regurgitation (MR) severity within 48 hours after cardiac resynchronization therapy (CRT) in patients with cardiomyopathy. METHODS: Sixty-nine cardiomyopathy patients (48 males, 21 females; mean age 59.12 ± 9.66 years) in NYHA functional class ≥III, with left ventricular ejection fraction (LVEF) ≤35%, and QRS duration >120 ms, with MR ≥moderate, were included in the study...
September 2017: Journal of Heart Valve Disease
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