A photoacoustic imaging system with variable gain at different depths

We established a photoacoustic imaging (PAI) system that can provide variable gain at different depths. The PAI system consists of a pulsed laser with an optical parametric oscillator working at a 728[Formula: see text]nm wavelength and an imaging-acquisition-and-processing unit with an ultrasound transducer. A voltage-controlled attenuator was used to realize variable gain at different depths when acquiring PAI signals. The proof-of-concept imaging results for variable gain at different depths were achieved using specific phantoms. Both resolution and optical contrast obtained through the results of variable gain for a targeted depth range are better than those of constant gain for all depths. To further testify the function, we imaged the sagittal section of the body of in vivo nude mice. In addition, we imaged an absorption sample embedded in a chicken breast tissue, reaching a maximum imaging depth of [Formula: see text]4.6[Formula: see text]cm. The results obtained using the proposed method showed better resolution and contrast than when using 50[Formula: see text]dB gain for all depths. The depth range resolution was [Formula: see text]1[Formula: see text]mm, and the maximum imaging depth of our system reached [Formula: see text]4.6[Formula: see text]cm. Furthermore, blood vessels can be revealed and targeted depth range can be selected in nude mice imaging.

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Sensitivity Enhanced Photoacoustic Imaging Using a High-Frequency PZT Transducer with an Integrated Front-End Amplifier

Sensors ◽

10.3390/s20030766 ◽

2020 ◽

Vol 20 (3) ◽

pp. 766 ◽

Cited By ~ 2

Author(s):

Chen Yang ◽

Xiaohua Jian ◽

Xinle Zhu ◽

Jiabing Lv ◽

Yang Jiao ◽

...

Keyword(s):

Breast Tissue ◽

Laser Energy ◽

Photoacoustic Imaging ◽

Biological Tissues ◽

Detection Sensitivity ◽

Chicken Breast ◽

Depth Range ◽

Front End ◽

Highly Sensitive

Photoacoustic (PA) imaging is a hybrid imaging technique that can provide both structural and functional information of biological tissues. Due to limited permissible laser energy deposited on tissues, highly sensitive PA imaging is required. Here, we developed a 20 MHz lead zirconium titanate (PZT) transducer (1.5 mm × 3 mm) with front-end amplifier circuits for local signal processing to achieve sensitivity enhanced PA imaging. The electrical and acoustic performance was characterized. Experiments on phantoms and chicken breast tissue were conducted to validate the imaging performance. The fabricated prototype shows a bandwidth of 63% and achieves a noise equivalent pressure (NEP) of 0.24 mPa/√Hz and a receiving sensitivity of 62.1 μV/Pa at 20 MHz without degradation of the bandwidth. PA imaging of wire phantoms demonstrates that the prototype is capable of improving the detection sensitivity by 10 dB compared with the traditional transducer without integrated amplifier. In addition, in vitro experiments on chicken breast tissue show that structures could be imaged with enhanced contrast using the prototype and the imaging depth range was improved by 1 mm. These results demonstrate that the transducer with an integrated front-end amplifier enables highly sensitive PA imaging with improved penetration depth. The proposed method holds the potential for visualization of deep tissue structures and enhanced detection of weak physiological changes.

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

Annals of Biomedical Engineering ◽

10.1007/s10439-021-02777-0 ◽

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.

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ANALYSIS OF ACOUSTIC ANISOTROPY PARAMETERS OF PYROXENE-MAGNETITE ROCKS OF THE PISCHANKA STRUCTURE

Visnyk of Taras Shevchenko National University of Kyiv Geology ◽

10.17721/1728-2713.88.06 ◽

2020 ◽

pp. 40-45

Author(s):

I. Bezrodna ◽

V. Svystov ◽

D. Bezrodny

Keyword(s):

Acoustic Properties ◽

Significant Heterogeneity ◽

Depth Range ◽

Transverse Waves ◽

Acoustic Anisotropy ◽

Micro Cracks ◽

Acoustic Tensor ◽

Transverse Isotropic ◽

Different Depths ◽

The Difference

The analysis of the results of acoustic properties of rocks study of Pischans`ka iron-ore structure is presented. The aim of the work is to establish the features of the distribution of acoustic properties and parameters of acoustic anisotropy in samples of core rocks selected from the well No. 3 of the Pischans`ka structure to determine the nature of its occurrence. A sample of 35 samples from the depth range 144-273 m is divided into 3 groups of rocks, namely: magnetite-pyroxene, quartz-magnetitepyroxene and biotite-amphibole crystalline shales. Based on an invariant polarization method, a number of acoustic laboratory measurements have been carried out. The values of the measured phase velocities "quasi-longitudinal" and two "quasi-transverse" waves at the stage of measurements showed significant acoustic anisotropy of the rocks. The ranges of the measured speeds of the collection samples are 7661 ÷ 5046 m / s for longitudinal waves and 4232 ÷ 2648 m/s for transverse ones. The difference in values measured for each of the sides of the cubic rhombic dodecahedron is from 100 to 800 m / s and from 0 to 500 m/s for Vp and Vs, respectively. The parameters of an acoustic ellipsoid were calculated, on the basis of which the division of samples into 3 main groups has been performed, according to the acoustic texture: acoustically linear, shale and rhombic. Separately, a group of samples with a more complex texture was discovered. The analysis of coefficients of anisotropy by different methods is carried out: longitudinal, transverse and relative acoustic anisotropy. Most of the samples are characterized by low or average acoustic anisotropy (from 2 to 7 %). A group of highly anisotropic rocks (11–14 %), represented by samples of biotite-amphibole crystalline silicates, is singled out. According to the parameters of the acoustic tensor of most samples, the transverse isotropic type of symmetry inherent to samples from the depth intervals 174–220 m and 222–232 m, while the smaller part is rhombic, is inherent. Differences in the parameters of anisotropy of samples can be explained by the significant heterogeneity of their textures, namely: micro cracks, minerals of various sizes, shapes and orientations. The results of the research show that the acoustic properties of the samples are quite heterogeneously distributed along the investigated depth range. This indicates the difficult conditions for the formation of rocks at different depths and the presence of different types of deformations, which accompanied the formation of the Pischans`ka structure.

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Juvenile fish in Cystoseira forests: influence of habitat complexity and depth on fish behaviour and assemblage composition

Mediterranean Marine Science ◽

10.12681/mms.18857 ◽

2019 ◽

Vol 20 (2) ◽

Author(s):

AMALIA CUADROS ◽

JOAN MORANTA ◽

LUIS CARDONA ◽

PIERRE THIRIET ◽

PATRICE FRANCOUR ◽

...

Keyword(s):

Body Length ◽

Fish Species ◽

Habitat Complexity ◽

Fish Assemblages ◽

Juvenile Fish ◽

The Body ◽

Environmental Drivers ◽

Independent Effect ◽

Depth Range ◽

Canopy Volume

The sublittoral forests formed by the fucoid algae Cystoseira spp. are important juvenile habitats for many Mediterranean fish species. However, the spatial variability of juvenile fish assemblages within the forests and the potential environmental drivers, such as depth and habitat complexity, remain poorly understood. We estimated densities, sizes and behaviours of juvenile fish assemblages in subtidal (0-15 meters) Cystoseira brachycarpa var. balearica forests in north Minorca Island (North-western Mediterranean Sea) over two consecutive autumns (2012 and 2013). Depth and forest complexity, here measured as canopy volume, had both a significant and independent effect on the juvenile fish assemblages in terms of species abundance composition and body size. Assemblages found in the shallowest depth range (3-4m) were characterized by greater densities of the ornate wrasse Thalassoma pavo, while those deeper (10-12m) had higher densities of the rainbow wrasse Coris julis, independently of its size composition. Juveniles of both species were more abundant in less complex forests; conversely juveniles of wrasses of the genus Symphodus were more abundant in more complex forests. The smallest sizes of T. pavo occurred in the most complex forests. On the other hand, our results demonstrated that juvenile fish behaviours were unrelated to the complexity of the Cystoseira forests but mainly related to the body length. The effects of body length on behaviour were however species dependent. Cryptic and transitory behaviours were mostly observed in the smallest and largest juveniles of T. pavo and C. julis, respectively, while the behaviour of Symphodus spp. was unrelated to their body length. Our study emphasises the importance of preserving healthy Cystoseira forests and their intrinsic patchy nature, as this habitat, with its mosaic of different complexity degrees and bathymetrical variability, enable the presence of different fish species at various life stages.

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An efficient local operator-based Q-compensated reverse time migration algorithm with multistage optimization

Geophysics ◽

10.1190/geo2017-0026.1 ◽

2018 ◽

Vol 83 (3) ◽

pp. S249-S259 ◽

Cited By ~ 5

Author(s):

Tong Zhou ◽

Wenyi Hu ◽

Jieyuan Ning

Keyword(s):

Seismic Attenuation ◽

Depth Information ◽

Frequency Noise ◽

Processing Unit ◽

Reverse Time ◽

Reverse Time Migration ◽

Pass Filter ◽

Low Pass Filter ◽

Time Migration ◽

Imaging Results

Most existing [Formula: see text]-compensated reverse time migration ([Formula: see text]-RTM) algorithms are based on pseudospectral methods. Because of the global nature of pseudospectral operators, these methods are not ideal for efficient parallelization, implying that they may suffer from high computational cost and inefficient memory usage for large-scale industrial problems. In this work, we reported a novel [Formula: see text]-RTM algorithm — the multistage optimized [Formula: see text]-RTM method. This [Formula: see text]-RTM algorithm uses a finite-difference method to compensate the amplitude and the phase simultaneously by uniquely combining two techniques: (1) a negative [Formula: see text] method for amplitude compensation and (2) a multistage dispersion optimization technique for phase correction. To prevent high-frequency noise from growing exponentially and ruining the imaging results, we apply a finite impulse response low-pass filter using the Kaiser window. The theoretical analyses and numerical experiments demonstrate that this [Formula: see text]-RTM algorithm precisely recovers the decayed amplitude and corrects the distorted phase caused by seismic attenuation effects, and hence produces higher resolution subsurface images with the correct structural depth information. This new method performs best in the frequency range of 10–70 Hz. Compared with pseudospectral [Formula: see text]-RTM methods, this [Formula: see text]-RTM approach offers nearly identical imaging quality. Based on local numerical differential operators, this [Formula: see text]-RTM method is very suitable for parallel computing and graphic processing unit implementation, an important feature for large 3D seismic surveys.

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Decapods Associated with the Southern King Crab (Lithodes santolla) Fishery in Central Patagonia (44° S, Chile)

Journal of Marine Science and Engineering ◽

10.3390/jmse9121353 ◽

2021 ◽

Vol 9 (12) ◽

pp. 1353

Author(s):

Guillermo Figueroa-Muñoz ◽

Carlos Molinet ◽

Manuel Díaz ◽

Patricio De los Ríos-Escalante

Keyword(s):

Generalized Linear Model ◽

Species Abundance ◽

Null Model ◽

The Body ◽

Fishery Resource ◽

King Crab ◽

Body Of Knowledge ◽

Chilean Patagonia ◽

Different Depths ◽

Total Species

The southern king crab, Lithodes santolla, is an important fishery resource in the inner seas of Chilean Patagonia. The fishing gear used to catch southern king crab (bait trap) and its operation at different depths over several months provide the opportunity to gather information about relative abundance. The aim of the present study was to analyze the information collected from the catches of southern king crab and its associated fauna in the Magdalena Fjord to study the biodiversity and ecology of scavenging decapod crustaceans. Specifically, the study aimed to determine the bathymetric patterns of abundance by species, to model the abundance by season (winter and spring) and to determine the structuring pattern of scavenging decapods assemblage. Samples were collected between June and November 2019 by deploying traps in four bathymetric strata: 1 = 0–50 m; 2 = 51–100 m; 3 =101–150 m; 4 = 151–200 m. We registered a total of 673 decapod specimens associated with the southern king crab fishery, representing five species: Lithodes santolla (n = 96), Libidoclaea smithii (n = 10), Metacarcinus edwardsii (n = 58), Munida gregaria (n = 507) and Peltarion spinulosum (n = 2). The abundance of decapod species varied by month and bathymetric strata. We found bathymetric patterns for L. santolla abundance, M. gregaria, M. edwardsii, and total species abundance. The most informative model to explain scavenging decapod abundance by generalized linear model (GLM) included species and season. The null model of species co-occurrence analysis revealed that all species associations during the sampled months were random. Our study is the first that provides evidence about patterns of bathymetrical and temporal variation of scavenging decapod abundance and expands the body of knowledge regarding the biodiversity of scavenger decapods in the Magdalena Sound.

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A Smart Binaural Hearing Aid Architecture Based on a Mobile Computing Platform

Electronics ◽

10.3390/electronics8070811 ◽

2019 ◽

Vol 8 (7) ◽

pp. 811

Author(s):

Yingdan Li ◽

Fei Chen ◽

Zhuoyi Sun ◽

Zhaoyang Weng ◽

Xian Tang ◽

...

Keyword(s):

Power Consumption ◽

Mobile Computing ◽

User Experience ◽

Speech Enhancement ◽

Hearing Aids ◽

Hearing Aid ◽

Binaural Hearing ◽

The Body ◽

Processing Unit ◽

Computing Platform

This paper presents a new structure for hearing aids. Normally, the power consumption and user experience are contradictory. The proposed hearing aid structure mainly consists of three parts: the earpieces, the mobile computing platform, and the real-time speech-enhancement application. It can run complex algorithms without carrying out heavy calculations on the processors in the hearing aid. Thus, the binaural algorithm is utilized without being limited by complexity and power consumption to improve the user experience. Moreover, the speech-enhancement algorithm can be updated much more easily than in traditional built-in digital signal process hearing aids. A good level of user experience is achieved by combining the hearing aid and mobile computing platform with a 400-MHz transceiver; furthermore, the 400-MHz transceiver can reduce path loss around the body. The concept verification process showed that the overall usage of the central processing unit in the smartphone is around 16%, the signal-to-noise ratios show at least a 30% improvement in some environments, and the whole system delay is 8.8 ms. The presented objective and subjective results show significant improvements regarding user experience and usability brought about by the proposed structure.

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A case of ovarian metastasis of gall bladder carcinoma simulating primary ovarian neoplasm: diagnostic pitfalls and review of literature

International Journal of Gynecological Cancer ◽

10.1136/ijgc-00009577-200602001-00054 ◽

2006 ◽

Vol 16 (Suppl 1) ◽

pp. 319-321 ◽

Cited By ~ 6

Author(s):

V. Jain ◽

K. Gupta ◽

R. Kudva ◽

G. S. Rodrigues

Keyword(s):

Gall Bladder ◽

Pelvic Mass ◽

Final Diagnosis ◽

Signet Ring Cell ◽

The Body ◽

Resected Specimen ◽

Signet Ring Cell Adenocarcinoma ◽

Imaging Results ◽

Signet Ring ◽

Frequent Site

The ovary is a relatively frequent site of metastases from malignant neoplasia arising elsewhere in the body, the majority of these originating from the gastrointestinal tract. The best-known tumor of this type is signet ring cell adenocarcinoma (Krukenberg tumor) of gastric origin and large bowel. The gall bladder and bile ducts are extremely rare sources of these metastases. The casuistic describes a female patient, presented with pelvic mass and jaundice. While clinical and imaging results suggested a primary ovarian carcinoma with incidental cholelithiasis and choledocholithiasis, the final diagnosis was obtained on the basis of histopathologic findings of resected specimen.

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

Scientific Reports ◽

10.1038/s41598-019-53990-w ◽

2019 ◽

Vol 9 (1) ◽

Cited By ~ 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.

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Three-Dimensional Numerical and Experimental Simulation of Wave Run-Up Due to Wave Impact With a Vertical Surface

Journal of Fluids Engineering ◽

10.1115/1.4039369 ◽

2018 ◽

Vol 140 (8) ◽

Cited By ~ 1

Author(s):

Armin Bodaghkhani ◽

Yuri S. Muzychka ◽

Bruce Colbourne

Keyword(s):

Vertical Surface ◽

The Body ◽

Experimental Simulation ◽

Processing Unit ◽

Plate Model ◽

Wave Impact ◽

Central Processing ◽

Break Up ◽

Run Up ◽

Good Agreement

This paper describes a numerical simulation of the interaction of a single nonlinear wave with a solid vertical surface in three dimensions. A coupled volume of fluid (VOF) and level set method (LSM) is used to simulate the wave-body interaction. A Cartesian-grid method is used to model immersed solid boundaries with constant grid spacing for simplicity and lower storage requirements. Mesh refinement is implemented near the wall boundaries due to the complex behavior of the free surface around the body. The behavior of the wave impact, the water sheet, and the high-speed jet arising from the wave impact are all captured with these methods. The numerical scheme is implemented using parallel computing due to the high central processing unit and memory requirements of this simulation. The maximum wave run-up velocity, instant wave run-up velocity in front of the vertical surface, the sheet break-up length, and the maximum impact pressure are computed for several input wave characteristics. Results are compared with a laboratory experiment that was carried out in a tow tank in which several generated waves were impacted with a fixed flat-shaped plate model. The numerical and experimental data on sheet breakup length are further compared with an analytical linear stability model for a viscous liquid sheet, and good agreement is achieved. The comparison between the numerical model and the experimental measurements of pressure, the wave run-up velocity, and the break-up length in front of the plate model shows good agreement.

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