... with radiologically defined unilateral hippocampal sclerosis. We performed voxel-based morphometric analysis of cortex and vertex-wise ... of the ipsilateral ventral pallidum (cluster size = 450 voxels, corrected p = 0.047, Max voxel coordinate = 107, 120, 65), medial thalamus (cluster size = 1128 voxels, corrected p = 0.049, Max voxel coordinate = 107, 93, 67), middle frontal gyrus (cluster size = 60 voxels, corrected p < 0.05, Max voxel coordinate = − 30, 49.5, 6), and contralateral posterior cingulate cortex (cluster size = 130 voxels, corrected p < 0.05, Max voxel coordinate = 16. ...
Tópico(s): Pharmacological Effects and Toxicity Studies
1980 - Elsevier BV | Hematology/Oncology Clinics of North America
Produção Nacional
Revisado por pares
R Krämer, Helen J. Khoury, José Wilson Vieira, Kate Brown,
... use the microCT images for skeletal dosimetry, spongiosa voxels in the skeletons were replaced at run time ... which have exactly the size of a spongiosa voxel and contain segmented trabecular bone and marrow micro-voxels. A cluster (=parallelepiped) of 2 x 2 x ... means that when a particle leaves a spongiosa voxel to enter into a neighboring spongiosa voxel, then the next micromatrix in the cluster will ... the particle travels through more than two spongiosa voxels in a row, then the cluster will be ... matrices and which was scanned with two different voxel resolutions. Taking into account a recent proposal, this ...
Tópico(s): Radiation Dose and Imaging
2009 - Wiley | Medical Physics
Steffen Hauth, Yavuz Murtezaoğlu, Lars Linsen,
... workpiece. The algorithm is based on an extended voxel structure. More precisely, we extend a voxel structure by adding distance values to the corner of the voxels and by linking empty voxels to non-empty voxels to accelerate finding the desired voxel. This ensures that we only need to consider ... collision area. The triangles within each non-empty voxel are stored in a bsp-tree. For empty voxels, we save information about the distances to the ... the mesh. The extra distance information in empty voxels enables a fast distance estimation and hence a ...
Tópico(s): Robotic Path Planning Algorithms
2009 - Elsevier BV | Computer-Aided Design
Hongtu Zhu, Yimei Li, Joseph G. Ibrahim, Weili Lin, Dinggang Shen,
... 3D volume for various neuroimaging studies. The existing voxel-wise approach has several major limitations for the ... underscoring the great need for methodological development. The voxel-wise approach essentially treats all voxels as independent units, whereas neuroimaging data are spatially ... usually expected. The initial smoothing step before the voxel-wise approach often blurs the image data near ... builds a small sphere at each location (called voxel) and use these consecutively connected spheres across all ...
Tópico(s): Spatial and Panel Data Analysis
2009 - Springer Science+Business Media | Lecture notes in computer science
Nikolaus Kriegeskorte, Rhodri Cusack, Peter A. Bandettini,
Recent studies suggested that fMRI voxel patterns can convey information represented in columnar-scale neuronal population codes, even when spatial resolution is insufficient to directly image the ... analysis techniques (Kriegeskorte and Bandettini, 2007). An individual voxel might weakly reflect columnar-level information if the ... fMRI hyperacuity (biased sampling by averaging within each voxel's boundaries; Kamitani and Tong, 2005) will only ... pattern information, and (c) that an alternative mechanism (voxel as complex spatiotemporal filter) is physiologically more accurate ...
Tópico(s): Advanced Neuroimaging Techniques and Applications
2009 - Elsevier BV | NeuroImage
Maria Vittoria Spampinato, J. N. Wood, V. De Simone, Jordan Grafman,
... AccessNeural Correlates of Anxiety in Healthy Volunteers: A Voxel-Based Morphometry StudyMaria Vittoria Spampinato M.D.Jacqueline ... report measures of level of anxiety on a voxel-by-voxel basis. Anxiety may be characterized by a combination ... evoking stimuli. In the present study we applied voxel-based morphometry (VBM) to high-resolution structural MRI ... small clusters, an extent threshold of 50 contiguous voxels was chosen. In VBM a statistical threshold of ... regionally specific gray matter volume differences on a voxel by voxel basis, while commonly used manual or ...
Tópico(s): Functional Brain Connectivity Studies
2009 - American Psychiatric Association Publishing | Journal of Neuropsychiatry
Maria Vittoria Spampinato, Jacqueline Wood, Veronica De Simone, Jordan Grafman,
... AccessNeural Correlates of Anxiety in Healthy Volunteers: A Voxel-Based Morphometry StudyMaria Vittoria Spampinato M.D.Jacqueline ... report measures of level of anxiety on a voxel-by-voxel basis. Anxiety may be characterized by a combination ... evoking stimuli. In the present study we applied voxel-based morphometry (VBM) to high-resolution structural MRI ... small clusters, an extent threshold of 50 contiguous voxels was chosen. In VBM a statistical threshold of ... regionally specific gray matter volume differences on a voxel by voxel basis, while commonly used manual or ...
Tópico(s): Neural and Behavioral Psychology Studies
2009 - American Psychiatric Association Publishing | Journal of Neuropsychiatry
Piotr Orłowski, Maciej Orkisz,
... uses matrix trace, determinant and sign to discard voxels unlikely to belong to vessels, prior to the ... in four computed tomography datasets (300 × 300 × 300 voxels) containing coronary and pulmonary arteries. The test based ... computation of the eigenvalues in half of the voxels on average, while the test combining the Hessian determinant and sign eliminated up to 10% additional voxels. The actual time savings depend on the algorithm used to compute the eigenvalues for the remaining voxels. With a very fast algorithm using a closed- ...
Tópico(s): Advanced Image Fusion Techniques
2009 - Elsevier BV | IRBM
Massimiliano Pacilio, Nico Lanconelli, S. Lo Meo, M. Betti, L. Montani, Leonel Alberto Torres Aroche, Marco Antonio Coca Pérez,
... MC) codes are available to perform calculations of voxel S values for radionuclide targeted therapy. The aim ... their impact on absorbed dose evaluations performed by voxel dosimetry. Voxel S values for monoenergetic sources (electrons and photons) ... The impact of the differences (in terms of voxel S values) among the MC codes was also ... simulations with monochromatic sources, differences for self-irradiation voxel S values were mostly confined within 10% for ... with electron energy less than 500 keV, the voxel S values referred to the first neighbor voxels ...
Tópico(s): Radiation Therapy and Dosimetry
2009 - Wiley | Medical Physics
D. G. Amen, J. R. Prunella, J. H. Fallon, Breanne Amen, C. Hanks,
... the Odyssey Step-20 software, which color-grades voxels based on their relative frequencies of photon emission. ... global image signal by using a Thresholded Mean Voxel Value in SPM2. We ran two different voxel-by-voxel one-tailed t tests in SPM2, one comparing ... differences comprised of a minimum of 30 contiguous voxels. We used a relative threshold mask of 80%, and voxels outside the brain were excluded from the analyses. ... low activity was a large contiguous 1,011-voxel cluster centered at Brodmann's area 25, encompassing ...
Tópico(s): Suicide and Self-Harm Studies
2009 - American Psychiatric Association Publishing | Journal of Neuropsychiatry
David C. Alsop, Alan Connelly, John S. Duncan, A. Hufnagel, Carlo Pierpaoli, Fergus Rugg‐Gunn,
... required to construct a diffusion ellipsoid in each voxel of an imaging volume (12). Specifically, it provides ... of the effective diffusion tensor, D, in each voxel of an imaging volume. From D it is ... the local "fiber" frame of reference in each voxel. Each eigenvalue is associated with a principal direction ( ... in which the description of diffusion in that voxel is the simplest and most natural. In each voxel, these eigenvalues can be sorted in order of ... parallel to a bundle of fibers within a voxel. We can use measurements of this eigenvector in ...
Tópico(s): MRI in cancer diagnosis
2002 - Wiley | Epilepsia
Katherine H. Taber, Carlo Pierpaoli, Stephen Rose, Fergus Rugg‐Gunn, Jonathan B. Chalk, Derek K. Jones, Robin A. Hurley,
... the second image for every location (volume element; voxel) within the brain section. The differences between the ... apparent diffusion constant or coefficient; ADC) for each voxel in the image. DW MR imaging is quite ... speed in each direction is calculated for every voxel in the image. This matrix is the diffusion ... to gliosis. The degree of anisotropy within each voxel provides information on structural integrity of white matter. ... Cover). The principal direction of diffusion in each voxel is represented by a color scheme in which ...
Tópico(s): Fetal and Pediatric Neurological Disorders
2002 - American Psychiatric Association Publishing | Journal of Neuropsychiatry
Yuichi Kimura, Michio Senda, Nathaniel M. Alpert,
Formation of parametric images requires voxel-by-voxel estimation of rate constants, a process sensitive to noise and computationally demanding. A model-based clustering method for a two-parameter model (CAKS) ... three-parameter model. The concept was to average voxels with similar kinetic signatures to reduce noise. Voxel kinetics were categorized by the first two principal ... of the tissue time–activity curves for all voxels. k2 and k3 were estimated cluster-by-cluster, and K1 was estimated voxel-by-voxel within clusters. When CAKS was applied ...
Tópico(s): Radiomics and Machine Learning in Medical Imaging
2002 - IOP Publishing | Physics in Medicine and Biology
... pixel size, 0.17 mm. To obtain cubic voxels, the consecutive cross-sectional slices were measured in ... the dark gray boxes contains 50 × 50 × 50 voxels (8.5 × 8.5 × 8.5 mm3). Superimposed ... possible to triangulate the surface of any given voxel array very quickly. The marching cubes algorithm is ... how a logical cube spawned by eight neighboring voxels is intersected by the surface. The resulting surface is a polygon represented by triangles. A voxel within a cube can either belong to the object or to the background. Depending on the voxel configurations within a cube, different triangulated surfaces will ...
Tópico(s): Radiomics and Machine Learning in Medical Imaging
2002 - Lippincott Williams & Wilkins | Topics in Magnetic Resonance Imaging
... compression algorithm for three-dimensional (3-D) binary voxel surfaces, based on the pattern code representation (PCR). In PCR, a voxel surface is represented by a series of pattern codes. The pattern of a voxel v is defined as the 3 /spl times/ 3 /spl times/ 3 array of voxels, centered on v. Therefore, the pattern code for v informs of the local shape of the voxel surface around v. The proposed algorithm can achieve the coding gain, since the patterns of adjacent voxels are highly correlated to each other. The performance ...
Tópico(s): Advanced Vision and Imaging
2002 - Institute of Electrical and Electronics Engineers | IEEE Transactions on Image Processing
Gustav Schonfeld, Bruce W. Patterson, Dmitriy A. Yablonskiy, Tariq Tanoli, Maurizio Averna, Nizar Elias, Pin Yue, Joseph J. H. Ackerman,
... of liver fat percentage determinations in three nonoverlapping voxels. Open table in a new tab Results are ... of liver fat percentage determinations in three nonoverlapping voxels. All MRS data were collected on a 1. ... 348Google Scholar) without water suppression was used. Accurate voxel localization was achieved by utilizing specially designed numerically ... 132: 260-265Google Scholar). This not only improved voxel localization but also almost doubled the signal-to-noise ratio by improving voxel profile. An outer volume suppression technique was used ...
Tópico(s): Lipid metabolism and biosynthesis
2003 - Elsevier BV | Journal of Lipid Research
Sakae Kinase, Masa Takahashi, Kimiaki Saitô,
... photons and electrons in the kidneys of a voxel mouse were evaluated using Monte Carlo simulations. The ... The self-AFs for the kidneys of the voxel mouse were compared with those for voxel humans. In addition, self-S values (μGy/MBq· ... found that the photon self-AFs for the voxel mouse are significantly smaller than those for the voxel humans and that the electron self-AFs for the voxel mouse are consistent with those for the voxel humans in the energy range 10-100 keV, ... sharp fall. The self-S values for the voxel mouse were found to be much larger than ...
Tópico(s): Effects of Radiation Exposure
2008 - Taylor & Francis | Journal of Nuclear Science and Technology
... interest. VI denotes the ratio of color-coded voxels to all voxels within the volume and is expressed as a ... power Doppler signal intensity from all color-coded voxels and VFI is the simple mathematical relationship derived ... VI actually quantifies the number of color-coded voxels, which does not necessarily mean the number of ... a correlation between the number of color-coded voxels and 'number of vessels'. This finding is in ... is just a ratio between colored and total voxels and, since voxels are actually small cubes that ...
Tópico(s): Hemodynamic Monitoring and Therapy
2008 - Wiley | Ultrasound in Obstetrics and Gynecology
Rajendra A. Morey, Teresa V. Mitchell, Seniha Inan, Jeffrey A. Lieberman, Ayşenil Belger,
... 5 ms, flip angle =20°, FOV =24 cm, voxel =0.9375×0.9375×1.5 mm, 256×256 voxels, 24 images), two-dimensional spin echo sequence (TR= ... 1500ms, TE=40ms, flip angle=90°, NEX=1, voxel=3.75×3.75×5 mm, imaging matrix 64×64 voxels) were acquired.Functional Image Analysis Our preliminary analysis ... event-related hemodynamic response. In a whole-brain voxel-based approach, individual participant t-maps were generated ... target event (AAT and UAD trials) by identifying voxels in which the average activity correlated with an ...
Tópico(s): Neural dynamics and brain function
2008 - American Psychiatric Association Publishing | Journal of Neuropsychiatry
John W. Ballrick, Juan Martín Palomo, Edward Ruch, B. Douglas Amberman, Mark G. Hans,
... was lower at faster scan times and larger voxel sizes. Conclusions: This CBCT machine has clinically accurate ... was lower at faster scan times and larger voxel sizes. Conclusions: This CBCT machine has clinically accurate ... size (cm)Scan time (s)⁎Manufacturer's specifications.Voxel size (mm)⁎Manufacturer's specifications.Exposure (s)⁎Manufacturer' ... variables were image size, seconds of scan, and voxel size. The coefficient of determination (R2) was calculated ... 0.1186 cm, 20 s, 0.4 mm voxel, mandibular0.033 ± 0.0660.046 ± 0.0920.039 ± ...
Tópico(s): Digital Radiography and Breast Imaging
2008 - Elsevier BV | American Journal of Orthodontics and Dentofacial Orthopedics
Michael G. Stabin, A.B. Brill,
Voxel dosimetry is a common approach to the internal dosimetry of non-uniform activity distributions in nuclear ... extend our analytical approach for the calculation of voxel S factors to materials different from the soft ... or photons was uniformly distributed within the central voxel, and the energy deposition was scored over the surrounding 11×11×11 voxels. Voxel S factors were obtained for the following standard ... standard ICRU materials: Bone compact and Muscle striated.Voxel S factors were represented as a function of ...
Tópico(s): Advanced Radiotherapy Techniques
2008 - Elsevier BV | Seminars in Nuclear Medicine
Clifford A. Smith, Glenn T. Stebbins, Russell Bartt, Harold A. Kessler, Oluwatoyin Adeyemi, Eileen Martin, Roland Bammer, Michael E. Moseley,
... by creating individual subject mask volumes to exclude voxels representing white matter abnormalities based on T2 signal, ... depressive symptoms and fractional anisotropy were evaluated using voxel-wise analysis of covariance and regression analyses in ... value of less than 0.05. For all voxel-wise comparisons, significance was determined with a p ... 001 with a contiguous cluster size of 20 voxels.RESULTSSociodemographic and Medical Data No differences in age, ... multiple comparisons) with an extent threshold of 20 voxels. Voxels evidencing significant differences in anisotropic diffusion are ...
Tópico(s): Functional Brain Connectivity Studies
2008 - American Psychiatric Association Publishing | Journal of Neuropsychiatry
Malin Björnsdotter, Johan Wessberg,
... multivariate machine learning approach to the identification of voxel clusters containing brain state discriminating information, serving as ... algorithm that, in conjunction with a classifier, extracts voxel clusters with a classification score above a pre- ... can be displayed as two- or three-dimensional voxel discrimination relevance maps (VDRMs), indicating where and to ... When applied to a finger-tapping dataset numerous voxel clusters with impressive classification rates were identified, at ... feature selection approach outperformed the GLM T-map voxel ranking method (e.g., group level AUC of ...
Tópico(s): Functional Brain Connectivity Studies
2008 - Institute of Electrical and Electronics Engineers | IEEE Journal of Selected Topics in Signal Processing
Edmund T. Rolls, Fabian Grabenhorst, Leonardo Franco,
... 80% correct from the activations of groups of voxels in the orbitofrontal and medial prefrontal cortex and ... prediction was typically a little better with multiple voxels than with one voxel, and the information increased sublinearly with the number of voxels up to typically seven voxels. Thus the information from different voxels was not independent, and there was considerable redundancy across voxels. This redundancy was present even when the voxels were from different brain areas. The pairwise stimulus- ...
Tópico(s): Neural and Behavioral Psychology Studies
2008 - American Physiological Society | Journal of Neurophysiology
Okito Yamashita, Masa-aki Sato, Taku Yoshioka, Frank Tong, Yukiyasu Kamitani,
... is important to choose an appropriate set of voxels (or features) as inputs to the decoder, since the presence of many irrelevant voxels could lead to poor generalization performance, a problem known as overfitting. Although individual voxels could be chosen based on univariate statistics, the resulting set of voxels could be suboptimal if correlations among voxels carry important information. Here, we propose a novel ... sparse logistic regression (SLR), that automatically selects relevant voxels while estimating their weight parameters for classification. Using ...
Tópico(s): Face Recognition and Perception
2008 - Elsevier BV | NeuroImage
Yoshikazu Nomura, Hiroshi Watanabe, Eiichi Honda, Tohru Kurabayashi,
... possible to evaluate bone mineral density (BMD) using voxel values from cone‐beam CT (CBCT) for dental ... imaged by CBCT and multi‐slice CT (MSCT). Voxel values and CT numbers, respectively, of the samples ... hydroxyapatite (HA) reference phantom, a conversion formula from voxel value to BMD was obtained. Results: There was a positive correlation between the voxel values of CBCT and the iodine concentration of ... ray dose or the mean energy, although the voxel values had a slight tendency to be saturated ... higher iodine concentrations. An excellent correlation between the voxel values and CT numbers was also observed. A ...
Tópico(s): Medical Imaging Techniques and Applications
2010 - Wiley | Clinical Oral Implants Research
Jason Langley, Wei Liu, Elaine Jordan, Joseph A. Frank, Qun Zhao,
... region. The magnetic field inhomogeneities dephase spins in voxels neighboring the nanoparticles. The dephasing caused by the ... Gradient The finite perturber method models (23) each voxel as a spherical dipole with the sphere embedded within each voxel. This method uses a scaling factor of (6/ ... to account for the excess volume within the voxel (23). The magnetic field for a magnetic dipole ... point, p, at a distance r outside the voxel is (3)where θ denotes the angle the ... the radius of the sphere embedded within the voxel, μ0 is the permeability of free space, and ...
Tópico(s): Advanced MRI Techniques and Applications
2010 - Wiley | Magnetic Resonance in Medicine
Rachmat Mulia, Christian Dupraz, Meine van Noordwijk,
... a 3D model based on both local (soil voxel level) and global (tree level) controls of root ... carbon to fine root growth in each rooted voxel depend on the success in water uptake in this voxel during the previous day, relative to overall supply ... at plant level. The allocated C in each voxel is then split into proliferation (within voxel growth) and extension into neighbouring voxels (colonisation), with scale-dependent thresholds and transfer coefficients. ... of a coarse root infrastructure linking all rooted voxels depends on the apparent need for adjustment of ...
Tópico(s): Plant Molecular Biology Research
2010 - Springer Science+Business Media | Plant and Soil
Pavel Lougovski, Jordan LeNoach, Lei Zhu, Yunzhi Ma, Yair Censor, Lei Xing,
... To establish an inverse planning framework with adjustable voxel penalty for more conformal IMRT dose distribution as ... with organ specific parameters is first performed. The voxel penalty scheme is then “switched on” by allowing the prescription dose to change on an individual voxel scale according to the deviation of the actual voxel dose from the ideally desired dose. The rationale here is intuitive: when the dose at a voxel does not meet its ideal dose, it simply implies that this voxel is not competitive enough when compared with the ...
Tópico(s): Radiopharmaceutical Chemistry and Applications
2010 - SAGE Publishing | Technology in Cancer Research & Treatment
Zikuan Chen, Arvind Caprihan, Vince D. Calhoun,
... magnetization will affect the magnetic field at a voxel in question. Existing reports on BOLD simulation only consider vasculature inside a single voxel, thus omitting the contribution from the surrounding regions. ... field and the BOLD signal at a cortical voxel by numerical simulation. Methods: A cortical voxel is generated as a cubic bin filled with ... capillary vessels. First, the authors generate a cortical voxel with a random vessel network and embed it in a greater voxel by filling its surrounding region with vasculatures by ...
Tópico(s): Advanced Neuroimaging Techniques and Applications
2010 - Wiley | Medical Physics