scholarly journals High-contrast photoacoustic imaging through scattering media using correlation detection of adaptive time window

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Liqi Yu ◽  
Jialin Sun ◽  
Xinjing Lv ◽  
Qi Feng ◽  
Huimei He ◽  
...  
Keyword(s):  
Light Scattering ◽  
Time Window ◽  
Photoacoustic Imaging ◽  
Signal To Noise Ratio ◽  
Photoacoustic Signal ◽  
High Contrast ◽  
Scattering Media ◽  
Window Method ◽  
Adaptive Time ◽  
Imaging Depth

AbstractPhotoacoustic imaging has the advantages of high contrast and deep imaging depth. However, with the increasing of imaging depth, the signal-to-noise ratio (SNR) of the detected signal decreases, due to the light scattering that seriously affects the recovery image quality. In this paper, we experimentally demonstrated that higher contrast photoacoustic imaging was achieved using photoacoustic wavefront shaping technology in the presence of light scattering and low SNR signals. The imaging contrast is improved from 1.51 to 5.30. More importantly, we propose a dynamic time window method for the photoacoustic signal extraction algorithm, named correlation detection of adaptive time window, which further improves the contrast of photoacoustic imaging to 9.57. Our method effectively improves the contrast of photoacoustic imaging through scattering media.

scholarly journals High contrast three-dimensional photoacoustic imaging through scattering media by localized optical fluence enhancement

2013 ◽  
Vol 21 (22) ◽  
pp. 26671 ◽  
Author(s):  
Antonio M. Caravaca-Aguirre ◽  
Donald B. Conkey ◽  
Jacob D. Dove ◽  
Hengyi Ju ◽  
Todd W. Murray ◽  
...  
Keyword(s):  
Photoacoustic Imaging ◽  
Three Dimensional ◽  
High Contrast ◽  
Scattering Media

scholarly journals Photoacoustic Imaging with Capacitive Micromachined Ultrasound Transducers: Principles and Developments

Sensors ◽  
2019 ◽  
Vol 19 (16) ◽  
pp. 3617 ◽  
Author(s):  
Jasmine Chan ◽  
Zhou Zheng ◽  
Kevan Bell ◽  
Martin Le ◽  
Parsin Haji Reza ◽  
...  
Keyword(s):  
Photoacoustic Imaging ◽  
Signal To Noise Ratio ◽  
Complementary Metal Oxide Semiconductor ◽  
Photoacoustic Signal ◽  
Motion Artifacts ◽  
Oxide Semiconductor ◽  
Ring Resonators ◽  
Ultrasound Transducers ◽  
Fabrication Technique ◽  
Acoustic Techniques

Photoacoustic imaging (PAI) is an emerging imaging technique that bridges the gap between pure optical and acoustic techniques to provide images with optical contrast at the acoustic penetration depth. The two key components that have allowed PAI to attain high-resolution images at deeper penetration depths are the photoacoustic signal generator, which is typically implemented as a pulsed laser and the detector to receive the generated acoustic signals. Many types of acoustic sensors have been explored as a detector for the PAI including Fabry–Perot interferometers (FPIs), micro ring resonators (MRRs), piezoelectric transducers, and capacitive micromachined ultrasound transducers (CMUTs). The fabrication technique of CMUTs has given it an edge over the other detectors. First, CMUTs can be easily fabricated into given shapes and sizes to fit the design specifications. Moreover, they can be made into an array to increase the imaging speed and reduce motion artifacts. With a fabrication technique that is similar to complementary metal-oxide-semiconductor (CMOS), CMUTs can be integrated with electronics to reduce the parasitic capacitance and improve the signal to noise ratio. The numerous benefits of CMUTs have enticed researchers to develop it for various PAI purposes such as photoacoustic computed tomography (PACT) and photoacoustic endoscopy applications. For PACT applications, the main areas of research are in designing two-dimensional array, transparent, and multi-frequency CMUTs. Moving from the table top approach to endoscopes, some of the different configurations that are being investigated are phased and ring arrays. In this paper, an overview of the development of CMUTs for PAI is presented.

scholarly journals Photoacoustic Signal Enhancement: Towards Utilization of Low Energy Laser Diodes in Real-Time Photoacoustic Imaging

Sensors ◽  
2018 ◽  
Vol 18 (10) ◽  
pp. 3498 ◽  
Author(s):  
Rayyan Manwar ◽  
Matin Hosseinzadeh ◽  
Ali Hariri ◽  
Karl Kratkiewicz ◽  
Shahryar Noei ◽  
...  
Keyword(s):  
Photoacoustic Imaging ◽  
Signal To Noise Ratio ◽  
Laser Diodes ◽  
Cost Effective ◽  
Photoacoustic Signal ◽  
Low Energy ◽  
Low Snr ◽  
Energy Laser ◽  
Noisy Measurements ◽  
Low Energy Laser

In practice, photoacoustic (PA) waves generated with cost-effective and low-energy laser diodes, are weak and almost buried in noise. Reconstruction of an artifact-free PA image from noisy measurements requires an effective denoising technique. Averaging is widely used to increase the signal-to-noise ratio (SNR) of PA signals; however, it is time consuming and in the case of very low SNR signals, hundreds to thousands of data acquisition epochs are needed. In this study, we explored the feasibility of using an adaptive and time-efficient filtering method to improve the SNR of PA signals. Our results show that the proposed method increases the SNR of PA signals more efficiently and with much fewer acquisitions, compared to common averaging techniques. Consequently, PA imaging is conducted considerably faster.

scholarly journals Resolution Limits in Photoacoustic Imaging Caused by Acoustic Attenuation

2019 ◽  
Vol 5 (1) ◽  
pp. 13 ◽  
Author(s):  
Peter Burgholzer ◽  
Johannes Bauer-Marschallinger ◽  
Bernhard Reitinger ◽  
Thomas Berer
Keyword(s):  
Acoustic Waves ◽  
Photoacoustic Imaging ◽  
Signal To Noise Ratio ◽  
Finite Size ◽  
Photoacoustic Signal ◽  
Dissipated Energy ◽  
Reconstruction Method ◽  
Square Root ◽  
Resolution Limit ◽  
Acoustic Attenuation

In conventional photoacoustic tomography, several effects contribute to the loss of resolution, such as the limited bandwidth and the finite size of the transducer, or the space-dependent speed of sound. They can all be compensated (in principle) technically or numerically. Frequency-dependent acoustic attenuation also limits spatial resolution by reducing the bandwidth of the photoacoustic signal, which can be numerically compensated only up to a theoretical limit given by thermodynamics. The entropy production, which is the dissipated energy of the acoustic wave divided by the temperature, turns out to be equal to the information loss, which cannot be compensated for by any reconstruction method. This is demonstrated for the propagation of planar acoustic waves in water, which are induced by short laser pulses and measured by piezoelectric acoustical transducers. It turns out that for water, where the acoustic attenuation is proportional to the squared frequency, the resolution limit is proportional to the square root of the distance and inversely proportional to the square root of the logarithm of the signal-to-noise ratio. The proposed method could be used in future work for media other than water, such as biological tissue, where acoustic attenuation has a different power-law frequency dependence.

A Time-Resolved Low-Angle Light Scattering Apparatus. Application to Phase Separation Problems in Polymer Systems

2001 ◽  
Vol 66 (6) ◽  
pp. 973-982 ◽  
Author(s):  
Čestmír Koňák ◽  
Jaroslav Holoubek ◽  
Petr Štěpánek
Keyword(s):  
Phase Separation ◽  
Light Scattering ◽  
Signal To Noise Ratio ◽  
Scattered Light ◽  
Ccd Camera ◽  
Time Resolved ◽  
Polymer Systems ◽  
Software Analysis ◽  
Phase Separation Kinetics ◽  
Small Angle Light Scattering

A time-resolved small-angle light scattering apparatus equipped with azimuthal integration by means of a conical lens or software analysis of scattering patterns detected with a CCD camera was developed. Averaging allows a significant reduction of the signal-to-noise ratio of scattered light and makes this technique suitable for investigation of phase separation kinetics. Examples of applications to time evolution of phase separation in concentrated statistical copolymer solutions and dissolution of phase-separated domains in polymer blends are given.

scholarly journals Locating and Imaging through Scattering Medium in a Large Depth

Sensors ◽  
2020 ◽  
Vol 21 (1) ◽  
pp. 90
Author(s):  
Shuo Zhu ◽  
Enlai Guo ◽  
Qianying Cui ◽  
Lianfa Bai ◽  
Jing Han ◽  
...  
Keyword(s):  
Phase Space ◽  
Signal To Noise Ratio ◽  
Speckle Pattern ◽  
Heuristic Method ◽  
Scattering Medium ◽  
Scattering Media ◽  
Signal To Noise ◽  
Practical Applications ◽  
Large Depth ◽  
Strong Scattering

Scattering medium brings great difficulties to locate and reconstruct objects especially when the objects are distributed in different positions. In this paper, a novel physics and learning-heuristic method is presented to locate and image the object through a strong scattering medium. A novel physics-informed framework, named DINet, is constructed to predict the depth and the image of the hidden object from the captured speckle pattern. With the phase-space constraint and the efficient network structure, the proposed method enables to locate the object with a depth mean error less than 0.05 mm, and image the object with an average peak signal-to-noise ratio (PSNR) above 24 dB, ranging from 350 mm to 1150 mm. The constructed DINet firstly solves the problem of quantitative locating and imaging via a single speckle pattern in a large depth. Comparing with the traditional methods, it paves the way to the practical applications requiring multi-physics through scattering media.

scholarly journals Towards Transabdominal Functional Photoacoustic Imaging of the Placenta: Improvement in Imaging Depth Through Optimization of Light Delivery

2021 ◽  
Author(s):  
Kristie Huda ◽  
Kenneth F. Swan ◽  
Cecilia T. Gambala ◽  
Gabriella C. Pridjian ◽  
Carolyn L. Bayer
Keyword(s):  
Delivery System ◽  
Light Propagation ◽  
Ex Vivo ◽  
Photoacoustic Imaging ◽  
Incidence Angle ◽  
Incident Angle ◽  
Placental Tissue ◽  
Light Delivery ◽  
Imaging Depth ◽  
The Impact

AbstractFunctional photoacoustic imaging of the placenta could provide an innovative tool to diagnose preeclampsia, monitor fetal growth restriction, and determine the developmental impacts of gestational diabetes. However, transabdominal photoacoustic imaging is limited in imaging depth due to the tissue’s scattering and absorption of light. The aim of this paper was to investigate the impact of geometry and wavelength on transabdominal light delivery. Our methods included the development of a multilayer model of the abdominal tissue and simulation of the light propagation using Monte Carlo methods. A bifurcated light source with varying incident angle of light, distance between light beams, and beam area was simulated to analyze the effect of light delivery geometry on the fluence distribution at depth. The impact of wavelength and the effects of variable thicknesses of adipose tissue and muscle were also studied. Our results showed that the beam area plays a major role in improving the delivery of light to deep tissue, in comparison to light incidence angle or distance between the bifurcated fibers. Longer wavelengths, with incident fluence at the maximum permissible exposure limit, also increases fluence within deeper tissue. We validated our simulations using a commercially available light delivery system and ex vivo human placental tissue. Additionally, we compared our optimized light delivery to a commercially available light delivery system, and conclude that our optimized geometry could improve imaging depth more than 1.6×, bringing the imaging depth to within the needed range for transabdominal imaging of the human placenta.

Effects of the SNAP25 on Integration Ability of Brain Functions in Children With ADHD

2020 ◽  
pp. 108705472096456
Author(s):  
Yue Yang ◽  
Gang Peng ◽  
Hongwu Zeng ◽  
Diangang Fang ◽  
Linlin Zhang ◽  
...  
Keyword(s):  
Time Window ◽  
Precentral Gyrus ◽  
Children With Adhd ◽  
Brain Functions ◽  
Lingual Gyrus ◽  
Window Method ◽  
Central Gyrus ◽  
The Right ◽  
The Brain ◽  
Insight Into

Objective: The present study aimed to examine the effects of SNAP25 on the integration ability of intrinsic brain functions in children with ADHD, and whether the integration ability was associated with working memory (WM). Methods: A sliding time window method was used to calculate the spatial and temporal concordance among five rs-fMRI regional indices in 55 children with ADHD and 20 healthy controls. Results: The SNAP25 exhibited significant interaction effects with ADHD diagnosis on the voxel-wise concordance in the right posterior central gyrus, fusiform gyrus and lingual gyrus. Specifically, for children with ADHD, G-carriers showed increased voxel-wise concordance in comparison to TT homozygotes in the right precentral gyrus, superior frontal gyrus, postcentral gyrus, and middle frontal gyrus. The voxel-wise concordance was also found to be related to WM. Conclusion: Our findings provided a new insight into the neural mechanisms of the brain function of ADHD children.

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