scholarly journals Pseudo‐spiral sampling and compressed sensing reconstruction provides flexibility of temporal resolution in accelerated aortic 4D flow MRI: A comparison with k‐t principal component analysis

2020 ◽  
Vol 33 (4) ◽  
Author(s):  
Lukas M. Gottwald ◽  
Eva S. Peper ◽  
Qinwei Zhang ◽  
Bram F. Coolen ◽  
Gustav J. Strijkers ◽  
...  
Keyword(s):  
Principal Component Analysis ◽  
Compressed Sensing ◽  
Temporal Resolution ◽  
Principal Component ◽  
Component Analysis ◽  
4D Flow Mri ◽  
4D Flow ◽  
Flow Mri

scholarly journals Hemodynamic measurements with an abdominal 4D flow MRI sequence with spiral sampling and compressed sensing in patients with chronic liver disease

2018 ◽  
Vol 49 (4) ◽  
pp. 994-1005 ◽  
Author(s):  
Octavia Bane ◽  
Steven Peti ◽  
Mathilde Wagner ◽  
Stefanie Hectors ◽  
Hadrien Dyvorne ◽  
...  
Keyword(s):  
Liver Disease ◽  
Compressed Sensing ◽  
Chronic Liver Disease ◽  
Chronic Liver ◽  
4D Flow Mri ◽  
4D Flow ◽  
Flow Mri ◽  
Hemodynamic Measurements

scholarly journals Effect of temporal resolution on 4D flow MRI in the portal circulation

2013 ◽  
Vol 39 (4) ◽  
pp. 819-826 ◽  
Author(s):  
Benjamin R. Landgraf ◽  
Kevin M. Johnson ◽  
Alejandro Roldán-Alzate ◽  
Christopher J. Francois ◽  
Oliver Wieben ◽  
...  
Keyword(s):  
Temporal Resolution ◽  
Portal Circulation ◽  
4D Flow Mri ◽  
4D Flow ◽  
Flow Mri

Abstract 14534: In vitro Assessment of Transvalvular Peak Velocity Measurement for Various Orifice Shapes: Comparison Between 4D Flow MRI vs. Doppler Echocardiography

Circulation ◽  
2020 ◽  
Vol 142 (Suppl_3) ◽  
Author(s):  
Jeesoo Lee ◽  
Nadia El hangouche ◽  
Liliana Ma ◽  
Michael Scott ◽  
Michael Markl ◽  
...  
Keyword(s):  
Temporal Resolution ◽  
Continuous Wave ◽  
Peak Velocity ◽  
Left Ventricular ◽  
Patient Specific ◽  
Maximal Velocity ◽  
4D Flow Mri ◽  
4D Flow ◽  
Flow Phantom ◽  
Flow Mri

Introduction: 4D flow MRI can assess transvalvular velocity, but validation against continuous wave (CW) Doppler echo is limited in high-velocity regurgitation and stenosis situations. We sought to compare 4D flow MRI and echo peak velocity using a pulsatile echo-MRI flow phantom. Materials and Methods: An MRI-compatible flow phantom with restrictive orifice situated was driven by a left ventricular assist device at 50 bpm (figure 1A). Three orifice shapes were tested: circular, elliptical and 3D-printed patient-specific mitral regurgitant orifice model of prolapse with areas of 0.5, 0.41 and 0.35 cm 2 , respectively. CW Doppler was acquired with peak velocity extracted from the profile. Retrospectively-gated 4D flow MRI was performed (spatial resolution = 2 mm isotropic, temporal resolution = 36 ms, encoding velocity = 400 cm/s). Maximal velocity magnitude was extracted volumetrically (figure 1B). An echo-mimicking profile was also obtained with a “virtual” ultrasound beam in the 4D flow data to simulate CW Doppler (figure 1C). Bland-Altman analysis was used to assess the agreement of temporal peak velocities. Results: 4D flow MRI demonstrated a centrally directed jet for the circular and elliptical orifices and an oblique jet for the prolapse orifice (figure 1B). Peak velocities were in excellent agreement between 4D flow MRI vs. echo for the circular (peak: 5.13 vs. 5.08 m/s, bias = 0.06 ± 0.66 m/s, figure 1D) and the elliptical orifice (peak: 4.95 vs. 4.79 m/s, bias = 0.07 ± 0.87 m/s, figure 1E). The prolapse orifice velocity was underestimated somewhat by MRI by ~10% (peak: 4.41 vs. 4.90 m/s, bias=0.26±1.18, figure 1F). Conclusion: 4D flow MRI can quantify high velocities like echo for simple geometries while underestimating for more complex geometry, likely due to partial volume effects. Further investigation is warranted to systematically investigate the effects of 4D flow MRI spatial and temporal resolution as well as the jet angle on velocity quantification accuracy.

Effect of temporal resolution on 4D flow MRI in the portal circulation

2014 ◽  
Vol 39 (4) ◽  
pp. spcone-spcone ◽  
Author(s):  
Benjamin R. Landgraf ◽  
Kevin M. Johnson ◽  
Alejandro Roldán-Alzate ◽  
Christopher J. Francois ◽  
Oliver Wieben ◽  
...  
Keyword(s):  
Temporal Resolution ◽  
Portal Circulation ◽  
4D Flow Mri ◽  
4D Flow ◽  
Flow Mri

scholarly journals Novel Magnetic Resonance Acquisition and Processing Strategies for Biological Tissue Characterisation

2021 ◽  
Author(s):  
◽  
Fangrong Zong
Keyword(s):  
Magnetic Field ◽  
Principal Component Analysis ◽  
Magnetic Resonance ◽  
Compressed Sensing ◽  
Fractional Anisotropy ◽  
Principal Component ◽  
Component Analysis ◽  
Tissue Characterisation ◽  
Diffusion Weighted ◽  
Field Strengths

<p>Proton magnetic resonance techniques have become indispensable for characterising tissues non-invasively. These methods provide abundant information regarding metabolism, morphology and histology of the sample under study. While these techniques were more expensive in the past compared to radioactive methods, modern advances in hardware and methodology provide the potential to use magnetic resonance systems more efficiently and widely. In this context, this thesis explored innovative magnetic resonance technologies from three independent perspectives which are suitable for tissue characterisation, utilising techniques from a wide range of disciplines including physics, engineering, biology and medical sciences.  One strategy relates to compressed sensing magnetic resonance imaging, seeking to recover detailed features at high undersampling rates. A data-adaptive sparse transform facilitated by principal component analysis was introduced as an alternative to the conventional pre-defined sparse transform. Moreover, the principal component analysis was used in a recognition algorithm for the reconstruction of undersampled data. The performances of these approaches were studied in cases of localised changes in the acquired images. The results demonstrated that the recognition reconstruction algorithm performed better than wavelet compressed sensing. This progress can be utilised to accelerate current state of the art imaging protocols at high magnetic field strengths. Furthermore, the prior knowledge contained in high resolution databases may enhance imaging capabilities of technologies at low magnetic field strengths.  A second approach exploits nuclear magnetic resonance diffusion contrast instead of contrast agents for tissue characterisation. Microstructural information and global fractional anisotropy can be obtained from diffusion-diffusion correlation spectroscopy via a novel multi-dimensional gradient scheme. The concept was validated by random walk simulations and experiments of biological samples. Both correlation maps and global fractional anisotropy of in vitro healthy and tumour-bearing mouse brains were found to be different, thus providing a potential application of the proposed scheme in diffusion oncology.  In addition, a threshold algorithm on the selection of a region of interest was implemented to minimise inter-observer variations. This technique was applied to a pilot study of diffusion weighted imaging data which were acquired from patients after x-ray mammography indicated lesions. The statistical analysis revealed an optimal threshold similar to values commonly used in positron emission tomography. Apart from selecting regions automatically, various data processing methods were implemented and compared with each other regarding their diagnostic accuracies. This field study provides opportunities for standardising procedures in diffusion weighted mammography, which may be integrated into clinical analysis in the future.</p>

scholarly journals Highly accelerated aortic 4D flow MRI using compressed sensing: Performance at different acceleration factors in patients with aortic disease

2020 ◽  
Vol 85 (4) ◽  
pp. 2174-2187
Author(s):  
Ashitha Pathrose ◽  
Liliana Ma ◽  
Haben Berhane ◽  
Michael B. Scott ◽  
Kelvin Chow ◽  
...  
Keyword(s):  
Compressed Sensing ◽  
Aortic Disease ◽  
4D Flow Mri ◽  
4D Flow ◽  
Flow Mri ◽  
Sensing Performance

scholarly journals Principal component analysis of ensemble recordings reveals cell assemblies at high temporal resolution

2009 ◽  
Vol 29 (1-2) ◽  
pp. 309-325 ◽  
Author(s):  
Adrien Peyrache ◽  
Karim Benchenane ◽  
Mehdi Khamassi ◽  
Sidney I. Wiener ◽  
Francesco P. Battaglia
Keyword(s):  
Principal Component Analysis ◽  
Temporal Resolution ◽  
Principal Component ◽  
Component Analysis ◽  
High Temporal Resolution ◽  
Cell Assemblies
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