Even though Magnetic Resonance Imaging (MRI) gives possibility to obtain qualitatively very good images, most quantitative results obtained by means of MRI are biased with high dependence on particular hardware parameters, imaging sequence used, and properties of analysed sample. Thus to enable comparison between results obtained on different scanners a calibration is needed. In one of the approaches to Diffusion Tensor Imaging (DTI), a B-matrix Spatial Distribution DTI (BSD-DTI) anisotropic phantoms are crucial in precise determination of the diffusion tensor. Anisotropic phantoms can be also useful as a porosity models or rock models in geology. The paper focuses on characterization of several anisotropic phantoms and describes their applications in DTI, and other domains related to MRI.
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http://dx.doi.org/10.1109/EMBC.2015.7318387 | DOI Listing |
Nan Fang Yi Ke Da Xue Xue Bao
January 2025
School of Mathematics and Computer Science, Gannan Normal University, Ganzhou 341000, China.
Objectives: We present a new low-dose CT reconstruction method using sub-pixel and anisotropic diffusion.
Methods: The sub-pixel intensity values and their second-order differences were obtained using linear interpolation techniques, and the new gradient information was then embedded into an anisotropic diffusion process, which was introduced into a penalty-weighted least squares model to reduce the noise in low-dose CT projection data. The high-quality CT image was finally reconstructed using the classical filtered back-projection (FBP) algorithm from the estimated data.
Biomed Phys Eng Express
January 2025
Department of Medical Radiation Sciences, Institute of Clinical Sciences, Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden.
Dual-polarity readout is a simple and robust way to mitigate Nyquist ghosting in diffusion-weighted echo-planar imaging but imposes doubled scan time. We here propose how dual-polarity readout can be implemented with little or no increase in scan time by exploiting an observed b-value dependence and signal averaging. The b-value dependence was confirmed in healthy volunteers with distinct ghosting at low b-values but of negligible magnitude at= 1000 s/mm.
View Article and Find Full Text PDFFront Neurosci
December 2024
Sherbrooke Connectivity Imaging Lab (SCIL), Computer Science Department, University of Sherbrooke, Sherbrooke, QC, Canada.
Magn Reson Med
December 2024
Mechanical Engineering and Materials Science, Washington University, St. Louis, Missouri, USA.
Purpose: Imaging phantoms with known anisotropic mechanical properties are needed to evaluate magnetic resonance elastography (MRE) methods to estimate anisotropic parameters. The aims of this study were to fabricate mechanically anisotropic MRE phantoms, characterize their mechanical behavior by direct testing, then assess the accuracy of MRE estimates of anisotropic properties using a transversely isotropic nonlinear inversion (TI-NLI) algorithm.
Methods: Directionally scaled and unscaled lattices were designed to exhibit anisotropic or isotropic mechanical properties.
Heliyon
November 2024
Department of Biomedical Engineering, Center for Biomedical and Robotics Technology (BART LAB), Faculty of Engineering, Mahidol University, Salaya, Thailand.
This study introduces a novel M-fiducial phantom-based automatic ultrasound (US) calibration technique aimed at improving 2D to 3D image registration in ultrasound-guided procedures. The technique addresses limitations in existing methods by enhancing feature extraction capabilities and improving calibration accuracy. The proposed method utilizes an M-fiducial phantom, an extended version of the standard N-fiducial phantom, designed to facilitate automatic extraction with a linear probe, particularly in small field-of-view scenarios.
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