scholarly journals Analysis of physiological noise in quantitative cardiac magnetic resonance

2019 ◽  
Author(s):  
Terrence Jao ◽  
Krishna Nayak
Keyword(s):  
Cardiac Magnetic Resonance ◽  
Magnetic Resonance ◽  
Parallel Imaging ◽  
Signal To Noise Ratio ◽  
Acceleration Factor ◽  
Physiological Noise ◽  
Matrix Size ◽  
Cardiac Mr ◽  
Bssfp Imaging ◽  
The Impact

AbstractPurposeTo determine the impact of imaging parameters on the temporal signal-to-noise ratio (TSNR) of quantitative cardiac magnetic resonance (MR) in humans, and to determine applicability of the physiological noise covariance (PNC) model for physiological noise (PN).MethodsWe conducted MRI experiments in four healthy volunteers, and obtained series of short-axis cardiac images acquired with snapshot balanced steady-state free precession (bSSFP) and snapshot gradient echo (GRE) using a broad range of spatial resolutions and parallel imaging acceleration factors commonly used in quantitative cardiac MR. We measured regional SNR and TSNR in these datasets and fit the measurements to the PNC model for PN, which assumes that PN scales with signal strength.ResultsThe relationship between SNR and TSNR in human cardiac MR without contrast preparation was well modeled by the PNC model. SNR consistently decreased as the spatial resolution (matrix size) and acceleration factor (R) increased for both GRE and bSSFP imaging. TSNR varied linearly with SNR using GRE imaging, when SNR was low (SNR < 20), and approached an asymptotic limit using bSSFP imaging, when SNR was high (SNR > 40).ConclusionsThe PNC model can be used to guide the choice of matrix size and acceleration factor to optimize TSNR in stable contrast cardiac MR, such as T2-prepared Blood-Oxygen-Level-Dependent (BOLD) and several variants of Arterial Spin Labeled (ASL) cardiac MR.

Cardiac magnetic resonance imaging in patients with systemic lupus erythematosus

2008 ◽  
Vol 68 (9) ◽  
pp. 1478-1481 ◽  
Author(s):  
S G O’Neill ◽  
S Woldman ◽  
F Bailliard ◽  
W Norman ◽  
J McEwan ◽  
...  
Keyword(s):  
Systemic Lupus Erythematosus ◽  
Cardiac Magnetic Resonance ◽  
Magnetic Resonance ◽  
Lupus Erythematosus ◽  
Control Group ◽  
Systemic Lupus ◽  
Gadolinium Contrast ◽  
Cardiac Mr ◽  
Group 4 ◽  
Male Patients

Objectives:To delineate the cardiac magnetic resonance (MR) appearances of cardiovascular disease (CVD) in patients with systemic lupus erythematosus (SLE), in comparison with transthoracic echocardiographs.Methods:Cardiac MR was performed on 22 patients with SLE—11 with previous CVD and 11 matched controls—using late gadolinium contrast enhancement (LGE) to identify areas of myocardial scarring; Transthoracic echocardiography (TTE) was performed on the same day.Results:Twenty female and two male patients participated. LGE was seen in 5/11 subjects in the CVD group (4/5 with previous myocardial infarction) and 1/11 in the control group. TTE detected myocardial abnormalities in 2/6 patients with LGE.Conclusion:The cardiac MR appearance of CVD in these patients with SLE was suggestive of coronary disease, rather than cumulative inflammatory muscle damage. Cardiac MR detected more abnormalities than TTE. Further studies of cardiac MR in patients with SLE are warranted to investigate these preliminary findings.

scholarly journals Maximizing the power of deep extragalactic imaging surveys with the James Webb Space Telescope

2019 ◽  
Vol 486 (3) ◽  
pp. 3087-3104 ◽  
Author(s):  
T W Kemp ◽  
J S Dunlop ◽  
R J McLure ◽  
C Schreiber ◽  
A C Carnall ◽  
...  
Keyword(s):  
Galaxy Evolution ◽  
Parallel Imaging ◽  
Near Infrared ◽  
Infrared Imaging ◽  
Current Knowledge ◽  
Signal To Noise Ratio ◽  
Added Value ◽  
Space Telescope ◽  
James Webb Space Telescope ◽  
The Impact

Abstract We present a new analysis of the potential power of deep, near-infrared, imaging surveys with the James Webb Space Telescope (JWST) to improve our knowledge of galaxy evolution. In this work we properly simulate what can be achieved with realistic survey strategies, and utilize rigorous signal-to-noise ratio calculations to calculate the resulting posterior constraints on the physical properties of galaxies. We explore a broad range of assumed input galaxy types (&gt;20 000 models, including extremely dusty objects) across a wide redshift range (out to z ≃ 12), while at the same time considering a realistic mix of galaxy properties based on our current knowledge of the evolving population (as quantified through the Empirical Galaxy Generator). While our main focus is on imaging surveys with NIRCam, spanning $\lambda _{\mathrm{ obs}} = 0.8\!-\!5.0\, \mu$m, an important goal of this work is to quantify the impact/added-value of: (i) parallel imaging observations with MIRI at longer wavelengths, and (ii) deeper supporting optical/UV imaging with HST (potentially prior to JWST launch) in maximizing the power and robustness of a major extragalactic NIRCam survey. We show that MIRI parallel 7.7-$\mu$m imaging is of most value for better constraining the redshifts and stellar masses of the dustiest (AV &gt; 3) galaxies, while deep B-band imaging (reaching ≃ 28.5 AB mag) with ACS on HST is vital for determining the redshifts of the large numbers of faint/low-mass, z &lt; 5 galaxies that will be detected in a deep JWST NIRCam survey.

scholarly journals Cardiac magnetic resonance parallel imaging at 3.0 Tesla: Technical feasibility and advantages

2004 ◽  
Vol 19 (3) ◽  
pp. 291-297 ◽  
Author(s):  
Kiaran P. McGee ◽  
Josef P. Debbins ◽  
Ed B. Boskamp ◽  
LeRoy Blawat ◽  
Lisa Angelos ◽  
...  
Keyword(s):  
Cardiac Magnetic Resonance ◽  
Magnetic Resonance ◽  
Parallel Imaging ◽  
3.0 Tesla ◽  
Technical Feasibility

Artifacts by Misalignment of Cardiac Magnetic Resonance Phased-array Coil Elements: From Simulation to In vivo Test

2019 ◽  
Vol 15 (3) ◽  
pp. 301-307
Author(s):  
Daniele De Marchi ◽  
Alessandra Flori ◽  
Nicola Martini ◽  
Giulio Giovannetti
Keyword(s):  
Cardiac Magnetic Resonance ◽  
Magnetic Resonance ◽  
Phased Array ◽  
Signal To Noise Ratio ◽  
Whole Body ◽  
Signal To Noise ◽  
Phased Array Coil ◽  
Noise Ratio ◽  
Array Coil

Background: Cardiac magnetic resonance evaluations generally require a radiofrequency coil setup comprising a transmit whole-body coil and a receive coil. In particular, radiofrequency phased-array coils are employed to pick up the signals emitted by the nuclei with high signal-tonoise ratio and a large region of sensitivity. Methods: Literature discussed different technical issues on how to minimize interactions between array elements and how to combine data from such elements to yield optimum Signal-to-Noise Ratio images. However, image quality strongly depends upon the correct coil position over the heart and of one array coil portion with respect to the other. Results: In particular, simple errors in coil positioning could cause artifacts carrying to an inaccurate interpretation of cardiac magnetic resonance images. Conclusion: This paper describes the effect of array elements misalignment, starting from coil simulation to cardiac magnetic resonance acquisitions with a 1.5 T scanner. </P><P> Phased-array coil simulation was performed using the magnetostatic approach; moreover, phantom and in vivo experiments with a commercial 8-elements cardiac phased-array receiver coil permitted to estimate signal-to-noise ratio and B1 mapping for aligned and shifted coil.

scholarly journals The Impact of Injector-Based Contrast Agent Administration on Bolus Shape and Magnetic Resonance Angiography Image Quality

2017 ◽  
Vol 10 ◽  
pp. 1178623X1770589 ◽  
Author(s):  
Gregor Jost ◽  
Jan Endrikat ◽  
Hubertus Pietsch
Keyword(s):  
Magnetic Resonance ◽  
Magnetic Resonance Angiography ◽  
Contrast Agent ◽  
Signal To Noise Ratio ◽  
Peak Height ◽  
Qualitative Comparison ◽  
Time To Peak ◽  
Magnetic Resonance Angiography Image ◽  
Test Bolus ◽  
The Impact

Objective: To compare injector-based contrast agent (CA) administration with hand injection in magnetic resonance angiography (MRA). Methods: Gadobutrol was administered in 6 minipigs with 3 protocols: (a) hand injection (one senior technician), (b) hand injection (6 less-experienced technicians), and (c) power injector administration. The arterial bolus shape was quantified by test bolus measurements. A head and neck MRA was performed for quantitative and qualitative comparison of signal enhancement. Results: A significantly shorter time to peak was observed for protocol C, whereas no significant differences between protocols were found for peak height and bolus width. However, for protocol C, these parameters showed a much lower variation. The MRA revealed a significantly higher signal-to-noise ratio for injector-based administration. A superimposed strong contrast of the jugular vein was found in 50% of the hand injections. Conclusions: Injector-based CA administration results in a more standardized bolus shape, a higher vascular contrast, and a more robust visualization of target vessels.

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