Search results for "vox"
showing 10 items of 126 documents
Essai de modélisation des dynamiques géospatiales en 3D+1D par automates voxellaires
2017
National audience; L’analyse des processus géographiques nécessite la prise en compte de l’espace tridimensionnel ainsi que le continuum espace-temps. Par ailleurs, le développement des nouvelles techniques d’acquisition et de consolidation de l’information géographique favorise l’émergence des modèles numériques 3D des espaces urbains. Cependant, la plupart des modèles de géosimulation actuels s’appuient sur une formalisation en deux dimensions du cadre spatial et la troisième dimension n’est prise en compte que par le biais de paramètres ou attributs de localisation.
A classification approach to prostate cancer localization in 3T Multi-Parametric MRI
2016
International audience; Multiparametric-magnetic resonance imaging (mp-MRI) has demonstrated, in many studies, its potential in prostate cancer detection and analysis. We propose a supervised classification approach based on mp-MRI data base of 20 patients, in order to localize prostate cancer and to achieve a cartographic representation of the prostate voxels based on classification results. Proposed method provides a computer aided detection (CAD) software for prostatic cancer. For that, we have extracted varied features providing functional, anatomical and metabolic information helping the classifier to distinguish between three different classes ("Healthy", "Benign" and "Pathologic"). W…
The change of volume of the lumbar vertebrae along with aging in asymptomatic population: a preliminary analysis
2018
Previous studies have demonstrated that the length of the lumbar spine is decreasing with age. Despite considerable research based on sagittal measurements, little is known about the changes in the volume of vertebrae. The objective of this study was to evaluate the changes in the volume of either column of the spine with age. Materials and methods: Computed tomography scans of 62 asymptomatic subjects, performed for thoracolumbar trauma evaluation were used to create virtual 3D models. At least 10 patients were assigned to every decade of life from third to eight. We used a novel technique to measure the volume of anterior column (AC) and posterior column (PC) per each segment (a total of …
Examining stability of independent component analysis based on coefficient and component matrices for voxel-based morphometry of structural magnetic …
2018
Independent component analysis (ICA) on group-level voxel-based morphometry (VBM) produces the coefficient matrix and the component matrix. The former contains variability among multiple subjects for further statistical analysis, and the latter reveals spatial maps common for all subjects. ICA algorithms converge to local optimization points in practice and the mostly applied stability investigation approach examines the stability of the extracted components. We found that the practically stable components do not guarantee to produce the practically stable coefficients of ICA decomposition for the further statistical analysis. Consequently, we proposed a novel approach including two steps: …
High performance of intravoxel incoherent motion diffusion MRI in detecting viral hepatitis-b induced liver fibrosis.
2019
Background: Recently a small cohort study demonstrated that intravoxel incoherent motion (IVIM) diffusion MRI can detect early stage liver fibrosis. Using modified IVIM data acquisition parameters, the current study aims to confirm this finding. Methods: Twenty-six healthy volunteers, three patients of chronic viral hepatitis-b but without fibrosis and one mild liver steatosis subject, and 12 viral hepatitis-b patients with fibrosis (stage 1–2=7, stage 3–4=5) were included in this study. With a 1.5-T MR scanner and respiration-gating, IVIM diffusion imaging was acquired using a single-shot echo-planar sequence with a b -value series of 2, 0, 1, 15, 20, 30, 45, 50, 60, 80, 100, 200, 300, 600…
Shift-Invariant Canonical Polyadic Decomposition of Complex-Valued Multi-Subject fMRI Data with a Phase Sparsity Constraint
2020
Canonical polyadic decomposition (CPD) of multi-subject complex-valued fMRI data can be used to provide spatially and temporally shared components among groups with both magnitude and phase information. However, the CPD model is not well formulated due to the large subject variability in the spatial and temporal modalities, as well as the high noise level in complex-valued fMRI data. Considering that the shift-invariant CPD can model temporal variability across subjects, we propose to further impose a phase sparsity constraint on the shared spatial maps to denoise the complex-valued components and to model the inter-subject spatial variability as well. More precisely, subject-specific time …
Chapter 4 3D brainstem topodiagnosis – a voxel-based model analyzing MR imaging data
2006
Publisher Summary This chapter presents a new method of statistically based three-dimensional (3D) brainstem mapping to identify brainstem structures responsible for specific clinical and electrophysiological abnormalities. To ensure reliable correlations, a large cohort of patients with magnetic resonance (MR)-documented brainstem infarctions were recruited in two European neurological institutions—namely, the Department of Neurology, Johannes Gutenberg University, Mainz, Germany, and the Department of Neurological Sciences, “La Sapienza” University of Rome, Italy. This method minimizes the risk of highlighting vascular territories rather than the structures specifically responsible for th…
"Ei se ole vaan laulua" : kuorolaisten kokemuksia Jyväskylän musiikkiluokkien A-kuoron ja Vox Aurean vaikutuksista
2017
Tutkimukseni tehtävänä on selvittää, miten Jyväskylän musiikkiluokkien A-kuorossa (sittemmin Vox Aurea) laulaneet ihmiset kokevat kuoron vaikuttaneen elämäänsä. Haastattelin tutkimukseeni viittä erilaisesta musiikillisesta taustasta tulevaa aikuista, jotka ovat laulaneet kuorossa sen alkuvuosina, sekä kuutta nuorta, jotka lauloivat kuorossa haastatteluhetkellä. Kahden eri sukupolven haastatteleminen mahdollistaa vertailun sen suhteen, ovatko kuorolaulun tärkeät ja vaikuttavat asiat huomattavasti muuttuneet kuoron alkuajoista nykypäivään. Haastattelu oli teemahaastattelu, jossa oli avoimen haastattelun piirteitä. Tutkimus on aineistolähtöinen ja aineistosta nousevan sosiaalisen näkökulman pa…
Glioma Grading: The Role of Combined Perfusion MR Imaging and Single-Voxel MR Spectroscopy Compared to Conventional MR Imaging
2011
Abstract Body: Purpose To assess the contribution of combined perfusion MR imaging (MRI) and single-voxel MR spectroscopy (MRS) in grading primary gliomas compared with conventional MRI. Materials & Methods Thirty-two patients with primary cerebral glioma underwent conventional MRI, dynamic contrast-enhanced T2*-weighted perfusion MRI and single-voxel proton MRS. Gliomas were graded as low or high based on conventional MRI. The rCBV measurements were obtained from regions of maximum perfusion normalized between tumor and healthy tissue. Metabolite ratios ( [Cho]/[Cr], [Cho]/[NAA], [NAA]/[Cr]) were measured with TE: 34 ms. Tumor grade determined with the three methods then was compared with …
Approaching electrical tomography
2009
A general approach to electrical tomography is here described, based on the distribution of the experimental data to the set of voxels in which the subsoil has been divided. This approach utilizes the sensitivity coefficients as factors of the convolution procedure to execute the back projection of the data, to obtain the 3D pictures of the subsoil. A subsequent probabilistic filtering technique is described to improve the pictures in view of sharp boundary models. Some models are finally presented, mostly regarding cubic buried anomalies as well as pipe-shaped and L-shaped anomalies.