Parametric analysis of the spatial resolution and signal-to-noise ratio in super-resolved spatiotemporally encoded (SPEN) MRI

In this article, an approach to designing and developing an ultrahigh frequency (≤600 MHz) ultrasound analog frontend with Golay coded excitation sequence for high resolution imaging applications is presented. For the purpose of visualizing specific structures or measuring functional responses of micron-sized biological samples, a higher frequency ultrasound is needed to obtain a decent spatial resolution while it lowers the signal-to-noise ratio, the difference in decibels between the signal level and the background noise level, due to the higher attenuation coefficient. In order to enhance the signal-to-noise ratio, conventional approach was to increase the transmit voltage level. However, it may cause damaging the extremely thin piezoelectric material in the ultrahigh frequency range. In this paper, we present a novel design of ultrahigh frequency (≤600 MHz) frontend system capable of performing pseudo Golay coded excitation by configuring four independently operating pulse generators in parallel and the consecutive delayed transmission from each channel. Compared with the conventional monocycle pulse approach, the signal-to-noise ratio of the proposed approach was improved by 7–9 dB without compromising the spatial resolution. The measured axial and lateral resolutions of wire targets were 16.4 µm and 10.6 µm by using 156 MHz 4 bit pseudo Golay coded excitation, respectively and 4.5 µm and 7.7 µm by using 312 MHz 4 bit pseudo Golay coded excitation, respectively.

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Beamformer enhancement by post-processing for improved spatial resolution and signal-to-noise ratio

10.1117/12.772942 ◽

2008 ◽

Author(s):

Kevin Owen ◽

Drake A. Guenther ◽

William F. Walker

Keyword(s):

Spatial Resolution ◽

Signal To Noise Ratio ◽

Post Processing ◽

Signal To Noise ◽

Noise Ratio

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X-ray shadowgraphy applications in ablatively accelerated planar foil studies

Laser and Particle Beams ◽

10.1017/s0263034600004614 ◽

1992 ◽

Vol 10 (4) ◽

pp. 685-688 ◽

Cited By ~ 3

Author(s):

V. A. Bolotin ◽

I. N. Burdonsky ◽

V. V. Gavrilov ◽

A. Yu. Gol'tsov ◽

E. V. Zhuzhukalo ◽

...

Keyword(s):

Laser Pulse ◽

Spatial Resolution ◽

Spectral Range ◽

Focal Spot ◽

Signal To Noise Ratio ◽

Signal To Noise ◽

Plasma Flows ◽

X Ray ◽

Noise Ratio ◽

Drive Laser Pulse

The article reviews experiments on flash X radiography of laser-accelerated foils. The spatial resolution, sensitivity, spectral range, and signal-to-noise ratio of measurements were carefully optimized and characterized. The method was used at the Mishen facility to measure a distribution of mass ablative rate across the focal spot and for observation of the transverse plasma flows during the drive laser pulse.

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The effect of spatial resolution on the reproducibility of diffusion imaging when controlled signal to noise ratio

Biomedical Journal ◽

10.1016/j.bj.2019.03.002 ◽

2019 ◽

Vol 42 (4) ◽

pp. 268-276 ◽

Cited By ~ 4

Author(s):

Yao-Liang Chen ◽

Yu-Jen Lin ◽

Sung-Han Lin ◽

Chih-Chien Tsai ◽

Yu-Chun Lin ◽

...

Keyword(s):

Spatial Resolution ◽

Signal To Noise Ratio ◽

Diffusion Imaging ◽

Signal To Noise ◽

Noise Ratio

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A Least-Squares Strain Estimator for Elastography

Ultrasonic Imaging ◽

10.1177/016173469701900303 ◽

1997 ◽

Vol 19 (3) ◽

pp. 195-208 ◽

Cited By ~ 326

Author(s):

Faouzi Kallel ◽

Jonathan Ophir

Keyword(s):

Least Squares ◽

Spatial Resolution ◽

Dynamic Range ◽

Signal To Noise Ratio ◽

Simulated Data ◽

Signal To Noise ◽

Noise Ratio ◽

Gel Phantom

A least-squares strain estimator (LSQSE) for elastography is proposed. It is shown that with such an estimator, the signal-to-noise ratio in an elastogram ( SNRe) is significantly improved. This improvement is illustrated theoretically using a modified strain filter and experimentally using a homogeneous gel phantom. It is demonstrated that the LSQSE results in an increase of the elastographic sensitivity (smallest strain that could be detected), thereby increasing the strain dynamic range. Using simulated data, it is shown that a tradeoff exists between the improvement in SNRe and the reduction of strain contrast and spatial resolution.

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Signal and noise in helioseismic holography

Astronomy and Astrophysics ◽

10.1051/0004-6361/201833825 ◽

2018 ◽

Vol 620 ◽

pp. A136 ◽

Cited By ~ 7

Author(s):

Laurent Gizon ◽

Damien Fournier ◽

Dan Yang ◽

Aaron C. Birch ◽

Hélène Barucq

Keyword(s):

Spatial Resolution ◽

Green's Function ◽

Sound Speed ◽

Signal To Noise Ratio ◽

Solar Interior ◽

Solar Oscillations ◽

Signal To Noise ◽

Holographic Image ◽

Image Intensity ◽

Noise Ratio

Context. Helioseismic holography is an imaging technique used to study heterogeneities and flows in the solar interior from observations of solar oscillations at the surface. Holographic images contain noise due to the stochastic nature of solar oscillations. Aims. We aim to provide a theoretical framework for modeling signal and noise in Porter–Bojarski helioseismic holography. Methods. The wave equation may be recast into a Helmholtz-like equation, so as to connect with the acoustics literature and define the holography Green’s function in a meaningful way. Sources of wave excitation are assumed to be stationary, horizontally homogeneous, and spatially uncorrelated. Using the first Born approximation we calculated holographic images in the presence of perturbations in sound-speed, density, flows, and source covariance, as well as the noise level as a function of position. This work is a direct extension of the methods used in time-distance helioseismology to model signal and noise. Results. To illustrate the theory, we compute the holographic image intensity numerically for a buried sound-speed perturbation at different depths in the solar interior. The reference Green’s function is obtained for a spherically-symmetric solar model using a finite-element solver in the frequency domain. Below the pupil area on the surface, we find that the spatial resolution of the holographic image intensity is very close to half the local wavelength. For a sound-speed perturbation of size comparable to the local spatial resolution, the signal-to-noise ratio is approximately constant with depth. Averaging the image intensity over a number N of frequencies above 3 mHz increases the signal-to-noise ratio by a factor nearly equal to the square root of N. This may not be the case at lower frequencies, where large variations in the holographic signal are due to the contributions from the long-lived modes of oscillation.

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