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https://www.readbyqxmd.com/read/28816657/a-dynamic-regression-approach-for-frequency-domain-partial-coherence-and-causality-analysis-of-functional-brain-networks
#1
Lipeng Ning, Yogesh Rathi
Coherence and causality measures are often used to analyze the influence of one region on another during analysis of functional brain networks. The analysis methods usually involve a regression problem where the signal of interest is decomposed into a mixture of regressor and a residual signal. In this paper, we revisit this basic problem and present solutions that provide the minimal-entropy residuals for different types of regression filters, such as causal, instantaneously causal and noncausal filters. Using optimal prediction theory, we derive several novel frequency-domain expressions for partial coherence, causality and conditional causality analysis...
August 14, 2017: IEEE Transactions on Medical Imaging
https://www.readbyqxmd.com/read/28812358/bioinspired-active-stealth-magneto-nanomicelles-for-theranostics-combining-efficient-mri-and-enhanced-drug-delivery
#2
Kai-Long Zhang, Jie Zhou, Hong Zhou, Ying Wu, Rui Liu, Li-Li Wang, Wei-Wen Lin, Guoming Huang, Huang-Hao Yang
The mononuclear phagocyte system (MPS), with key roles in recognition and clearance of foreign particles, is a major constraint to nanoparticle-based delivery systems. The desire to improve the delivery efficiency has prompted the search for stealthy long-circulating nanoplatforms. Herein, we design an antiphagocytic delivery system with "active" stealth behavior for cancer theranostics combining efficient MRI and enhanced drug delivery. We modify self-peptide, a synthetic peptide for active immunomodulation, to biodegradable poly (lactide-glycolide)-poly (ethylene glycol) (PLGA-PEG), then utilize the self-assembly properties of PLGA-PEG to form nanomicelles that encapsulating iron oxide (IO) nanoparticles and anticancer drug paclitaxel (PTX)...
August 16, 2017: ACS Applied Materials & Interfaces
https://www.readbyqxmd.com/read/28809668/tractography-based-score-for-learning-effective-connectivity-from-multimodal-imaging-data-using-dynamic-bayesian-networks
#3
Shilpa Dang, Santanu Chaudhury, Brejesh Lall, Prasun K Roy
OBJECTIVE: Effective connectivity (EC) is the methodology for determining functional-integration among the functionally-active segregated regions of the brain. By definition [1] EC is "the causal influence exerted by one neuronal group on another" which is constrained by anatomical connectivity (AC) (axonal connections). AC is necessary for EC but does not fully determine it, because synaptic communication occurs dynamically in a context-dependent fashion. Although there is a vast emerging evidence of structure-function relationship using multimodal imaging studies, till date only a few studies have done joint modelling of the two modalities: functional MRI (fMRI) and Diffusion Tensor Imaging (DTI)...
August 10, 2017: IEEE Transactions on Bio-medical Engineering
https://www.readbyqxmd.com/read/28803112/in-vivo-documentation-of-shape-and-position-changes-of-mri-visible-mesh-placed-in-rectovaginal-septum
#4
Urbankova Iva, Sindhwani Nikhil, Callewaert Geertje, Turri Alice, Rinkijevic Rita, Hympanova Lucie, Feola Andrew, Deprest Jan
BACKGROUND AND OBJECTIVE: Large deformations in synthetic meshes used in pelvic organ prolapse surgery may lead to suboptimal support for the underlying tissue, graft-related complications as well as recurrence. Our aim was to quantify in vivo longitudinal changes in mesh shape and geometry in a large animal model. We compare two commonly used mesh shapes, armed and flat, that are differently affixed. The secondary outcomes were active and passive biomechanical properties. METHODS: A total of 18 animals were used...
August 5, 2017: Journal of the Mechanical Behavior of Biomedical Materials
https://www.readbyqxmd.com/read/28789598/development-of-a-computerized-4-d-mri-phantom-for-liver-motion-study
#5
Chunhao Wang, Fang-Fang Yin, W P Segars, Zheng Chang, Lei Ren
PURPOSE: To develop a 4-dimensional computerized magnetic resonance imaging phantom with image textures extracted from real patient scans for liver motion studies. METHODS: The proposed phantom was developed based on the current version of 4-dimensional extended cardiac-torso computerized phantom and a clinical magnetic resonance scan. Initially, the extended cardiac-torso phantom was voxelized in abdominal-chest region at the end of exhalation phase. Structures/tissues were classified into 4 categories: (1) Seven key textured organs, including liver, gallbladder, spleen, stomach, heart, kidneys, and pancreas, were mapped from a clinical T1-weighted liver magnetic resonance scan using deformable registration...
January 1, 2017: Technology in Cancer Research & Treatment
https://www.readbyqxmd.com/read/28781414/test-suite-for-image-based-motion-estimation-of-the-brain-and-tongue
#6
Jordan Ramsey, Jerry L Prince, Arnold D Gomez
Noninvasive analysis of motion has important uses as qualitative markers for organ function and to validate biomechanical computer simulations relative to experimental observations. Tagged MRI is considered the gold standard for noninvasive tissue motion estimation in the heart, and this has inspired multiple studies focusing on other organs, including the brain under mild acceleration and the tongue during speech. As with other motion estimation approaches, using tagged MRI to measure 3D motion includes several preprocessing steps that affect the quality and accuracy of estimation...
February 11, 2017: Proceedings of SPIE
https://www.readbyqxmd.com/read/28777721/infinite-von-mises-fisher-mixture-modeling-of-whole-brain-fmri-data
#7
Rasmus E Røge, Kristoffer H Madsen, Mikkel N Schmidt, Morten Mørup
Cluster analysis of functional magnetic resonance imaging (fMRI) data is often performed using gaussian mixture models, but when the time series are standardized such that the data reside on a hypersphere, this modeling assumption is questionable. The consequences of ignoring the underlying spherical manifold are rarely analyzed, in part due to the computational challenges imposed by directional statistics. In this letter, we discuss a Bayesian von Mises-Fisher (vMF) mixture model for data on the unit hypersphere and present an efficient inference procedure based on collapsed Markov chain Monte Carlo sampling...
August 4, 2017: Neural Computation
https://www.readbyqxmd.com/read/28735215/estimation-of-individual-axon-bundle-properties-by-a-multi-resolution-discrete-search-method
#8
Ricardo Coronado-Leija, Alonso Ramirez-Manzanares, Jose Luis Marroquin
A stable, accurate and robust-to-noise method for the estimation of the intra-voxel bundle-wise diffusion properties for diffusion-weighted magnetic resonance imaging is presented. The proposed method overcomes some of the limitations of most of the multi-fiber algorithms in the literature and extends them to estimate the diffusion profiles, improving the estimation of the intra-voxel geometry at challenging microstructure configurations, that is to say: relatively small crossing angles, different voxel-wise anisotropic diffusion profiles and low SNR...
June 29, 2017: Medical Image Analysis
https://www.readbyqxmd.com/read/28725549/performance-of-unscented-kalman-filter-tractography-in-edema-analysis-of-the-two-tensor-model
#9
Ruizhi Liao, Lipeng Ning, Zhenrui Chen, Laura Rigolo, Shun Gong, Ofer Pasternak, Alexandra J Golby, Yogesh Rathi, Lauren J O'Donnell
Diffusion MRI tractography is increasingly used in pre-operative neurosurgical planning to visualize critical fiber tracts. However, a major challenge for conventional tractography, especially in patients with brain tumors, is tracing fiber tracts that are affected by vasogenic edema, which increases water content in the tissue and lowers diffusion anisotropy. One strategy for improving fiber tracking is to use a tractography method that is more sensitive than the traditional single-tensor streamline tractography...
2017: NeuroImage: Clinical
https://www.readbyqxmd.com/read/28719864/in-vivo-magnetic-resonance-imaging-of-pancreatic-tumors-using-iron-oxide-nanoworms-targeted-with-ptr86-peptide
#10
Yasaman Ahmadi, Genady Kostenich, Mor Oron-Herman, Wolfgang Wadsak, Markus Mitterhauser, Arie Orenstein, Siroos Mirzaei, Peter Knoll
To cut the high mortality rate of malignant disease such as pancreatic cancer, development of newly diagnostic probes for early stage detection of tumor lesions is required. Multimodal imaging nanoprobes allowing targeted and real time functional/anatomical imaging of tumors meet the demands. For this purpose, a MRI/optical dual-modality probe based on biodegradable magnetic iron oxide nanoworms has been developed. The cross-linked surface of nanoworms were anchored to fluorescent dyes and to FITC.PTR86; a novel synthetic peptide with high affinity towards somatostatin receptors...
July 6, 2017: Colloids and Surfaces. B, Biointerfaces
https://www.readbyqxmd.com/read/28714303/melittin-containing-hybrid-peptide-hydrogels-for-enhanced-photothermal-therapy-of-glioblastoma
#11
Honglin Jin, Guifang Zhao, Jianli Hu, Quanguang Ren, Kui Yang, Chao Wan, Ai Huang, Pindong Li, Jue-Ping Feng, Jing Chen, Zhenwei Zou
The design of biocompatible and efficacious anticancer biomaterials to achieve relatively low tumor recurrence rates is the main pursuit of cancer photothermal therapy (PTT). RADA16-I is a synthetic amphiphilic peptide with the sequence RADARADARADARADA that can self-assemble into a peptide nanofiber hydrogel. In this study, we synthesized a novel melittin-RADA32-indocyanine green (ICG) hydrogel ("MRI hydrogel"), which contains melittin in the peptide hydrogel backbone and ICG in the hydrogel matrix, for enhanced PTT of glioblastomas...
August 9, 2017: ACS Applied Materials & Interfaces
https://www.readbyqxmd.com/read/28695243/cns-metabolism-in-high-risk-drug-abuse-insights-gained-from-1-h-31-p-mrs-and-pet
#12
REVIEW
S Bodea
BACKGROUND: High-risk drug consumption is a matter of great concern for public health actors in industrialised countries. The latest trends show a market tendency towards diversification and increasing demand for high-purity synthetic drugs. While most consumers seek medical help after cannabis use, it is high-risk drugs like cocaine, heroin and amphetamines that account for most of the 1000 drug-related deaths that occur in Germany every year. PURPOSE: This article presents the most prominent in vivo cerebral metabolic information in cocaine, heroin and methamphetamine users provided by MRI spectroscopy and PET imaging...
July 10, 2017: Der Radiologe
https://www.readbyqxmd.com/read/28690126/-mri-based-radiotherapy-planning
#13
A Largent, J-C Nunes, C Lafond, N Périchon, J Castelli, Y Rolland, O Acosta, R de Crevoisier
MRI-based radiotherapy planning is a topical subject due to the introduction of a new generation of treatment machines combining a linear accelerator and a MRI. One of the issues for introducing MRI in this task is the lack of information to provide tissue density information required for dose calculation. To cope with this issue, two strategies may be distinguished from the literature. Either a synthetic CT scan is generated from the MRI to plan the dose, or a dose is generated from the MRI based on physical underpinnings...
July 6, 2017: Cancer Radiothérapie: Journal de la Société Française de Radiothérapie Oncologique
https://www.readbyqxmd.com/read/28678701/a-planning-and-guidance-platform-for-cardiac-resynchronization-therapy
#14
Peter Mountney, Jonathan M Behar, Daniel Toth, Maria Panayiotou, Sabrina Reiml, Marie-Pierre Jolly, Rashed Karim, Li Zhang, Alexander Brost, Christopher A Rinaldi, Kawal Rhode
Patients with drug-refractory heart failure can greatly benefit from cardiac resynchronization therapy (CRT). A CRT device can resynchronize the contractions of the left ventricle (LV) leading to reduced mortality. Unfortunately 30- 50% of patients do not respond to treatment when assessed by objective criteria such as cardiac remodeling. A significant contributing factor is suboptimal placement of the LV lead. It has been shown that placing this lead away from scar and at the point of latest mechanical activation can improve response rates...
June 27, 2017: IEEE Transactions on Medical Imaging
https://www.readbyqxmd.com/read/28677254/partial-volume-model-for-brain-mri-scan-using-mp2rage
#15
Quentin Duché, Hervé Saint-Jalmes, Oscar Acosta, Parnesh Raniga, Pierrick Bourgeat, Vincent Doré, Gary F Egan, Olivier Salvado
MP2RAGE is a T1 weighted MRI sequence that estimates a composite image providing much reduction of the receiver bias, has a high intensity dynamic range, and provides an estimate of T1 mapping. It is, therefore, an appealing option for brain morphometry studies. However, previous studies have reported a difference in cortical thickness computed from MP2RAGE compared with widely used Multi-Echo MPRAGE. In this article, we demonstrated that using standard segmentation and partial volume estimation techniques on MP2RAGE introduces systematic errors, and we proposed a new model to estimate partial volume of the cortical gray matter...
July 5, 2017: Human Brain Mapping
https://www.readbyqxmd.com/read/28669918/estimation-of-white-matter-fiber-parameters-from-compressed-multiresolution-diffusion-mri-using-sparse-bayesian-learning
#16
Pramod Kumar Pisharady, Stamatios N Sotiropoulos, Julio M Duarte-Carvajalino, Guillermo Sapiro, Christophe Lenglet
We present a sparse Bayesian unmixing algorithm BusineX: Bayesian Unmixing for Sparse Inference-based Estimation of Fiber Crossings (X), for estimation of white matter fiber parameters from compressed (under-sampled) diffusion MRI (dMRI) data. BusineX combines compressive sensing with linear unmixing and introduces sparsity to the previously proposed multiresolution data fusion algorithm RubiX, resulting in a method for improved reconstruction, especially from data with lower number of diffusion gradients. We formulate the estimation of fiber parameters as a sparse signal recovery problem and propose a linear unmixing framework with sparse Bayesian learning for the recovery of sparse signals, the fiber orientations and volume fractions...
June 29, 2017: NeuroImage
https://www.readbyqxmd.com/read/28669751/finite-element-analysis-to-investigate-variability-of-mr-elastography-in-the-human-thigh
#17
L Hollis, E Barnhill, M Perrins, P Kennedy, N Conlisk, C Brown, P R Hoskins, P Pankaj, N Roberts
PURPOSE: To develop finite element analysis (FEA) of magnetic resonance elastography (MRE) in the human thigh and investigate inter-individual variability of measurement of muscle mechanical properties. METHODS: Segmentation was performed on MRI datasets of the human thigh from 5 individuals and FEA models consisting of 12 muscles and surrounding tissue created. The same material properties were applied to each tissue type and a previously developed transient FEA method of simulating MRE using Abaqus was performed at 4 frequencies...
June 29, 2017: Magnetic Resonance Imaging
https://www.readbyqxmd.com/read/28661074/a-review-of-recent-developments-of-mesoporous-materials
#18
REVIEW
Steven L Suib
This personal account concerns novel recent discoveries in the area of mesoporous materials. Most of the papers discussed have been published within the last two to three years. A major emphasis of most of these papers is the synthesis of unique mesoporous materials by a variety of synthetic methods. Many of these articles focus on the control of the pore sizes and shapes of mesoporous materials. Synthetic methods of various types have been used for such control of porosity including soft templating, hard templating, nano-casting, electrochemical methods, surface functionalization, and trapping of species in pores...
June 29, 2017: Chemical Record: An Official Publication of the Chemical Society of Japan ... [et Al.]
https://www.readbyqxmd.com/read/28655418/synthesis-and-characterization-of-monophosphinic-acid-dota-derivative-a-smart-tool-with-functionalities-for-multimodal-imaging
#19
Satya Narayana Murthy Chilla, Ondrej Zemek, Jan Kotek, Sébastien Boutry, Lionel Larbanoix, Coralie Sclavons, Luce Vander Elst, Ivan Lukes, Robert N Muller, Sophie Laurent
A new facile synthetic strategy was developed to prepare bifunctional monophosphinic acid Ln-DOTA derivatives, Gd-DO2AGAP(NBn) and Gd- DO2AGAP(ABn). The relaxivities of the Gd-complexes are enhanced compared to Gd-DOTA. Monophosphinic acid arm of these Gd-complexes affords enhancement of inner sphere water exchange rate due to its steric bulkiness. The different functionalities of DO2AGAP(NBn) were appended in trans positions and are designed to conjugate identical or different vectors according to the potential applications...
August 15, 2017: Bioorganic & Medicinal Chemistry
https://www.readbyqxmd.com/read/28651599/dosimetric-evaluation-of-synthetic-ct-for-magnetic-resonance-only-based-radiotherapy-planning-of-lung-cancer
#20
Hesheng Wang, Hersh Chandarana, Kai Tobias Block, Thomas Vahle, Matthias Fenchel, Indra J Das
BACKGROUND: Interest in MR-only treatment planning for radiation therapy is growing rapidly with the emergence of integrated MRI/linear accelerator technology. The purpose of this study was to evaluate the feasibility of using synthetic CT images generated from conventional Dixon-based MRI scans for radiation treatment planning of lung cancer. METHODS: Eleven patients who underwent whole-body PET/MR imaging following a PET/CT exam were randomly selected from an ongoing prospective IRB-approved study...
June 26, 2017: Radiation Oncology
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