نتایج جستجو برای: partial volume effect
تعداد نتایج: 2103220 فیلتر نتایج به سال:
UNLABELLED PET imaging of D(2) receptors or (18)F-L-dopa metabolism are reference protocols to follow and study neurodegenerative diseases, but the accuracy of striatal PET imaging is limited by the partial-volume effect (PVE). For such studies, the geometric transfer matrix (GTM) method has been proposed to correct the regional mean values for PVE and is now widely used. METHODS The GTM meth...
The partial volume effect (PVE) significantly restricts the absolute quantification of regional myocardial uptake and thereby limits the accuracy of absolute measurement of blood flow and coronary flow reserve by SPECT. The template-projection-reconstruction method has been previously developed for PVE compensation. This method assumes the availability of coregistered high-spatial resolution an...
UNLABELLED We present software for integrated analysis of brain PET studies and coregistered segmented MRI that couples a module for automated placement of regions of interest (ROI) with 4 alternative methods for partial-volume-effect correction (PVEc). The accuracy and precision of these methods have been measured using 4 simulated (18)F-FDG PET studies with increasing degrees of atrophy. ME...
Quantitative analyses of computed tomography images are prone to errors due to the partial volume effect which affects objects (e.g., bones) that have a different size or are assessed with different resolution. We have developed a set of equations suitable for both modeling the partial volume effect in cortical bone and for performing the corresponding adjustment. Seven hollow cylinders and 2 c...
Quantitative accuracy of positron emission tomography (PET) is decreased by the partial volume effect (PVE). The PVE correction (PVC) methods proposed by Alfano et al., Rousset et al., Müller-Gärtner et al. and Meltzer et al. were evaluated in the present study to obtain guidelines for selecting among them. For accuracy evaluation, the Hoffman brain phantom was scanned with three PETs of differ...
Magnetic resonance spectroscopic imaging (MRSI) is currently used clinically in conjunction with anatomical MRI to assess the presence and extent of brain tumors and to evaluate treatment response. Unfortunately, the clinical utility of MRSI is limited by significant variability of in vivo spectra. Spectral profiles show increased variability because of partial coverage of large voxel volumes, ...
Iterative reconstruction methods relying on linearization of the relationship between images and projections have to cope with the inherent representation of the scanned object by voxel elements. When the voxel size becomes large enough to reduce the overall computational requirements, partial volume can become an issue for overall image quality. We propose in this paper a linear parametric mod...
Segmentation of Magnetic Resonance Imaging (MRI) is a process of assigning tissue class labels to voxels. One of the main sources of segmentation error is the partial volume effect (PVE) which occurs most often with low resolution images – with large voxels, the probability of a voxel containing multiple tissue classes increases. We propose a multistage algorithm for segmenting MRI images with ...
Analyzing gray matter diffusion properties can be challenging due to possible measurement biases originating from averaging of gray matter (GM) and cerebrospinal fluid (CSF) signals. Therefore, a better characterization of CSF contamination effects in different cortical regions is required in order to disentangle actual changes in microstructure of GM itself from changes due to other effects su...
Partial-volume Bayesian classification of material mixtures in MR volume data using voxel histograms
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