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1.
Small ; : e2312221, 2024 Jul 15.
Artigo em Inglês | MEDLINE | ID: mdl-39007285

RESUMO

Ultrasound imaging is extensively used in biomedical science and clinical practice. Imaging resolution and tunability of imaging plane are key performance indicators, but both remain challenging to be improved due to the longer wavelength compared with light and the lack of zoom lens for ultrasound. Here, the ultrasound zoom imaging based on a stretchable planar metalens that simultaneously achieves the subwavelength imaging resolution and dynamic control of the imaging plane is reported. The proposed zoom imaging ultrasonography enables precise bone fracture diagnosis and comprehensive osteoporosis assessment. Millimeter-scale microarchitectures of the cortical bones at different depths can be selectively imaged with a 0.6-wavelength resolution. The morphological features of bone fractures, including the shape, size and position, are accurately detected. Based on the extracted ultrasound information of cancellous bones with healthy matrix, osteopenia and osteoporosis, a multi-index osteoporosis evaluation method is developed. Furthermore, it provides additional biological information in aspects of bone elasticity and attenuation to access the comprehensive osteoporosis assessment. The soft metalens also features flexibility and biocompatibility for preferable applications on wearable devices. This work provides a strategy for the development of high-resolution ultrasound biomedical zoom imaging and comprehensive bone quality diagnosis system.

2.
Opt Lett ; 49(8): 1949-1952, 2024 Apr 15.
Artigo em Inglês | MEDLINE | ID: mdl-38621048

RESUMO

Methods have been proposed in recent years aimed at pushing photoacoustic imaging resolution beyond the acoustic diffraction limit, among which those based on random speckle illumination show particular promise. In this Letter, we propose a data-driven deep learning approach to processing the added spatiotemporal information resulting from speckle illumination, where the neural network learns the distribution of absorbers from a series of different samplings of the imaged area. In ex-vivo experiments based on the tomography configuration with prominent artifacts, our method successfully breaks the acoustic diffraction limit and delivers better results in identifying individual targets when compared against a selection of other leading methods.

3.
Phys Rev Lett ; 132(11): 114001, 2024 Mar 15.
Artigo em Inglês | MEDLINE | ID: mdl-38563918

RESUMO

The Doppler effect is a universal wave phenomenon that has inspired various applications due to the induced frequency shift. In the case of the linear Doppler effect, the frequency shift depends on the incident frequency and angle. Here, we unveil the frequency shift dependence induced by the acoustic rotational Doppler effect in the wave-object scattering process. We experimentally demonstrate that this frequency shift is exclusively determined by the angular speed and rotational symmetry of the spinning scatterer while remaining independent of the incident angular momentum and angle. We derive the analytical relationship between the frequency shift and the scatterer's helicity, presenting a novel approach for helical feature recognition. The angle-independent nature of the frequency shift inherently prevents spectrum broadening and offers a solution for precise motion measurement through the rotational Doppler effect. This work provides a rigorous and comprehensive understanding of the acoustic Doppler effect, enriching its applications in helicity and motion detection.

4.
J Ultrasound Med ; 2024 Jun 14.
Artigo em Inglês | MEDLINE | ID: mdl-38873702

RESUMO

OBJECTIVES: To develop a robust algorithm for estimating ultrasonic axial transmission velocity from neonatal tibial bone, and to investigate the relationships between ultrasound velocity and neonatal anthropometric measurements as well as clinical biochemical markers of skeletal health. METHODS: This study presents an unsupervised learning approach for the automatic detection of first arrival time and estimation of ultrasonic velocity from axial transmission waveforms, which potentially indicates bone quality. The proposed method combines the ReliefF algorithm and fuzzy C-means clustering. It was first validated using an in vitro dataset measured from a Sawbones phantom. It was subsequently applied on in vivo signals collected from 40 infants, comprising 21 males and 19 females. The extracted neonatal ultrasonic velocity was subjected to statistical analysis to explore correlations with the infants' anthropometric features and biochemical indicators. RESULTS: The results of in vivo data analysis revealed significant correlations between the extracted ultrasonic velocity and the neonatal anthropometric measurements and biochemical markers. The velocity of first arrival signals showed good associations with body weight (ρ = 0.583, P value <.001), body length (ρ = 0.583, P value <.001), and gestational age (ρ = 0.557, P value <.001). CONCLUSION: These findings suggest that fuzzy C-means clustering is highly effective in extracting ultrasonic propagating velocity in bone and reliably applicable in in vivo measurement. This work is a preliminary study that holds promise in advancing the development of a standardized ultrasonic tool for assessing neonatal bone health. Such advancements are crucial in the accurate diagnosis of bone growth disorders.

5.
J Acoust Soc Am ; 155(4): 2670-2686, 2024 Apr 01.
Artigo em Inglês | MEDLINE | ID: mdl-38639562

RESUMO

Recently, ultrasound transit time spectroscopy (UTTS) was proposed as a promising method for bone quantitative ultrasound measurement. Studies have showed that UTTS could estimate the bone volume fraction and other trabecular bone structure in ultrasonic through-transmission measurements. The goal of this study was to explore the feasibility of UTTS to be adapted in ultrasonic backscatter measurement and further evaluate the performance of backscattered ultrasound transit time spectrum (BS-UTTS) in the measurement of cancellous bone density and structure. First, taking ultrasonic attenuation into account, the concept of BS-UTTS was verified on ultrasonic backscatter signals simulated from a set of scatterers with different positions and intensities. Then, in vitro backscatter measurements were performed on 26 bovine cancellous bone specimens. After a logarithmic compression of the BS-UTTS, a linear fitting of the log-compressed BS-UTTS versus ultrasonic propagated distance was performed and the slope and intercept of the fitted line for BS-UTTS were determined. The associations between BS-UTTS parameters and cancellous bone features were analyzed using simple linear regression. The results showed that the BS-UTTS could make an accurate deconvolution of the backscatter signal and predict the position and intensity of the simulated scatterers eliminating phase interference, even the simulated backscatter signal was with a relatively low signal-to-noise ratio. With varied positions and intensities of the scatterers, the slope of the fitted line for the log-compressed BS-UTTS versus ultrasonic propagated distance (i.e., slope of BS-UTTS for short) yield a high agreement (r2 = 99.84%-99.96%) with ultrasonic attenuation in simulated backscatter signal. Compared with the high-density cancellous bone, the low-density specimen showed more abundant backscatter impulse response in the BS-UTTS. The slope of BS-UTTS yield a significant correlation with bone mineral density (r = 0.87; p < 0.001), BV/TV (r = 0.87; p < 0.001), and cancellous bone microstructures (r up to 0.87; p < 0.05). The intercept of BS-UTTS was also significantly correlated with bone densities (r = -0.87; p < 0.001) and trabecular structures (|r|=0.43-0.80; p < 0.05). However, the slope of the BS-UTTS underestimated attenuation when measurements were performed experimentally. In addition, a significant non-linear relationship was observed between the measured attenuation and the attenuation estimated by the slope of the BS-UTTS. This study demonstrated that the UTTS method could be adapted to ultrasonic backscatter measurement of cancellous bone. The derived slope and intercept of BS-UTTS could be used in the measurement of bone density and microstructure. The backscattered ultrasound transit time spectroscopy might have potential in the diagnosis of osteoporosis in the clinic.


Assuntos
Osso e Ossos , Osso Esponjoso , Animais , Bovinos , Osso Esponjoso/diagnóstico por imagem , Espalhamento de Radiação , Ultrassonografia/métodos , Osso e Ossos/diagnóstico por imagem , Densidade Óssea/fisiologia , Análise Espectral/métodos
6.
Opt Lett ; 48(3): 656-659, 2023 Feb 01.
Artigo em Inglês | MEDLINE | ID: mdl-36723556

RESUMO

Quick identification of abnormal molecular metabolism of bone tissues is challenging. Photoacoustic (PA) spectroscopy techniques have great potential in molecular imaging. However, most of them are amplitude-dependent and easily affected by the light deposition, especially for bone tissues with high optical scattering. In this Letter, we propose a Nakagami statistics-based PA spectroscopy (NSPS) method for characterizing molecules in bone tissues. We indicate that the NSPS curve can intelligently identify changes in the content of molecules in bone tissues, with a high disturbance-resisting ability. The NSPS has remarkable potential for use in the early and rapid detection of bone diseases.


Assuntos
Técnicas Fotoacústicas , Ultrassonografia/métodos , Espalhamento de Radiação , Análise Espectral/métodos , Osso e Ossos/diagnóstico por imagem
7.
J Bone Miner Metab ; 41(5): 592-605, 2023 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-37270713

RESUMO

INTRODUCTION: Moderate exercise benefits bone health, but excessive loading leads to bone fatigue and a decline in mechanical properties. Low-intensity pulsed ultrasound (LIPUS) can stimulate bone formation. The purpose of this study was to explore whether LIPUS could augment the skeletal benefits of high-intensity exercise. MATERIALS AND METHODS: MC3T3-E1 osteoblasts were treated with LIPUS at 80 mW/cm2 or 30 mW/cm2 for 20 min/day. Forty rats were divided into sham treatment normal control (Sham-NC), sham treatment high-intensity exercise (Sham-HIE), 80 mW/cm2 LIPUS (LIPUS80), and high-intensity exercise combined with 80 mW/cm2 LIPUS (LIPUS80-HIE). The rats in HIE group were subjected to 30 m/min slope treadmill exercise for 90 min/day, 6 days/week for 12 weeks. The LIPUS80-HIE rats were irradiated with LIPUS (1 MHz, 80 mW/cm2) for 20 min/day at bilateral hind limb after exercise. RESULTS: LIPUS significantly accelerated the proliferation, differentiation, mineralization, and migration of MC3T3-E1 cells. Compared to 30 mW/cm2 LIPUS, 80 mW/cm2 LIPUS got better promotion effect. 12 weeks of high-intensity exercise significantly reduced the muscle force, which was significantly reversed by LIPUS. Compared with the Sham-NC group, Sham-HIE group significantly optimized bone microstructure and enhanced mechanical properties of femur, and LIPUS80-HIE further enhanced the improvement effect on bone. The mechanisms may be related to activate Wnt/ß-catenin signal pathway and then up-regulate the protein expression of Runx2 and VEGF, the key factors of osteogenesis and angiogenesis. CONCLUSION: LIPUS could augment the skeletal benefits of high-intensity exercise through Wnt/ß-catenin signal pathway.


Assuntos
Ondas Ultrassônicas , beta Catenina , Ratos , Animais , Diferenciação Celular , Músculos , Via de Sinalização Wnt
8.
J Acoust Soc Am ; 154(1): 279-294, 2023 07 01.
Artigo em Inglês | MEDLINE | ID: mdl-37449785

RESUMO

Recently, full-waveform inversion (FWI) has become a promising tool for ultrasound computed tomography (USCT). However, as a computationally intensive technique, FWI suffers from computational burden, especially in conventional time-domain full-waveform inversion (TDFWI). On the contrary, frequency-domain full-waveform inversion (FDFWI) provides a relatively high computational efficiency as the propagation of discrete frequencies is much cheaper than full time-domain modeling. FDFWI has already been applied in soft tissue imaging, such as breast, but for the musculoskeletal model with high impedance contrast between hard and soft tissues, there is still a lack of an effective source estimation method. In this paper, a water-referenced data calibration method is proposed to address the source estimation challenge in the presence of bones, which achieves consistency between the measured and simulated data before the FDFWI procedure. To avoid the cycle-skipping local minimum effect and facilitate the algorithm convergence, a starting frequency criterion for musculoskeletal FDFWI is further proposed. The feasibility of the proposed method is demonstrated by numerical studies on retrieving the anatomies of the leg models and different musculoskeletal lesions. The study extends the advanced FDFWI method to the musculoskeletal system and provides an alternative solution for musculoskeletal USCT imaging with high computational efficiency.


Assuntos
Algoritmos , Tomografia Computadorizada por Raios X , Tomografia Computadorizada por Raios X/métodos , Ultrassonografia/métodos , Osso e Ossos
9.
Adv Exp Med Biol ; 1364: 95-117, 2022.
Artigo em Inglês | MEDLINE | ID: mdl-35508872

RESUMO

A new application of ultrasonography has been emerging in the bone quantitative ultrasound arena in the last twenty years: cortical bone characterization using axial transmission ultrasound (ATU). Although challenged by the complicated cortical tissue-ultrasonic wave interaction, ATU has proved to have promising potential to be a valuable diagnostic tool in the assessment of cortical bones. This chapter reviews the main landmarks of axial transmission signal processing in the past decade to provide a guide to the diversity of available techniques. In order to increase the readability of the chapter, the signal processing methods are categorized based on the experimental settings: single and multiple transmitter-receiver configuration. The review considers the key stages required for the analysis of bone guided-wave ultrasound data namely dispersion energy imaging, modal filtering, dispersion curve inversion, and measurement automation with integrated artificial intelligence concepts. Besides discussing the recent signal processing advances in the field of bone assessment by axial transmission, this communication offers developments that might be anticipated in the near future.


Assuntos
Inteligência Artificial , Processamento de Sinais Assistido por Computador , Osso e Ossos/diagnóstico por imagem , Osso Cortical/diagnóstico por imagem , Ultrassonografia
10.
Ultrason Imaging ; 44(2-3): 59-76, 2022 05.
Artigo em Inglês | MEDLINE | ID: mdl-35373649

RESUMO

Fast and efficient imaging techniques are important for real-time ultrasound imaging. The delay and sum (DAS) beamformer is the most widely-used strategy in focused ultrasound imaging (FUI) modality. However, calculating the time delays and coherently summing the amplitude response in DAS is computationally expensive and generally require a high-performance processor to realize real-time processing. In this study, an efficient spectrum beamformer, namely full-matrix capture (FMC)-stolt, is proposed in FUI system with a linear phased array. The imaging performance of FMC-stolt was validated with the point-scatter simulation and in vitro point and cyst phantoms, and then compared with that of five beamformers, that is, Multiline acquisition (MLA), retrospective transmit beamforming (RTB) in the FUI modality, as well as DAS, Garcia's frequency-wavenumber (f-k), Lu's f-k in the coherent plane wave compounding imaging (CPWCI) modality, under specific conditions. We show that the imaging performance of FMC-stolt is better than MLA-DAS in non-transmit-focal regions, and comparable with RTB-DAS at all imaging depths. FMC-stolt also shows better discontinuity alleviation than MLA and RTB. In addition, FMC-stolt has similar imaging characteristics (e.g., off-axis resolution, computational cost) as the f-k beamformers. The computational complexity and actual computational time indicate that FMC-stolt is comparable to Garcia's f-k, Lu's f-k, and faster than RTB and CPWCI-DAS if the transmitting numbers are close for FUI and CPWCI. The study demonstrates that the proposed FMC-stolt could achieve good reconstruction speed while preserving high-quality images and thus provide a choice for software beamforming for conventional B-mode ultrasound imaging, especially for hand-held devices with limited performance processors.


Assuntos
Algoritmos , Processamento de Imagem Assistida por Computador , Simulação por Computador , Processamento de Imagem Assistida por Computador/métodos , Imagens de Fantasmas , Estudos Retrospectivos , Ultrassonografia/métodos
11.
Small ; 17(45): e2102052, 2021 11.
Artigo em Inglês | MEDLINE | ID: mdl-34605161

RESUMO

A flexible fiber acoustic transducer is created by designing a parallel configuration of a Rubidium iron boron (NdFeB) magnet fiber and an aluminum fiber. The former provides a stable magnet field, while the latter vibrates to phonate upon applying alternating current or generates alternating voltage in the sound field. This single device exhibits dual functions as a loudspeaker or a microphone. As a fiber loudspeaker, it can generate 40-60 dB of audible (20 Hz-20 kHz) and directional sounds which can be used for blind navigation and controllable sound field distribution. The fiber acoustic transducer functions as a microphone when external sound waves force the aluminum fiber to vibrate. After the fiber microphones are woven into several different positions of a piece of clothing, the sound source can be accurately located based on the time differences reaching different microphones. This wearable fiber acoustic transducer is promising to be used to quickly search people in trouble during emergency rescue activities such as earthquakes or fires.


Assuntos
Acústica , Transdutores , Fenômenos Eletromagnéticos , Humanos , Som
12.
Ultrason Imaging ; 43(6): 308-319, 2021 11.
Artigo em Inglês | MEDLINE | ID: mdl-34470531

RESUMO

Large scale early scanning of fetuses via ultrasound imaging is widely used to alleviate the morbidity or mortality caused by congenital anomalies in fetal hearts and lungs. To reduce the intensive cost during manual recognition of organ regions, many automatic segmentation methods have been proposed. However, the existing methods still encounter multi-scale problem at a larger range of receptive fields of organs in images, resolution problem of segmentation mask, and interference problem of task-irrelevant features, obscuring the attainment of accurate segmentations. To achieve semantic segmentation with functions of (1) extracting multi-scale features from images, (2) compensating information of high resolution, and (3) eliminating the task-irrelevant features, we propose a multi-scale model with skip connection framework and attention mechanism integrated. The multi-scale feature extraction modules are incorporated with additive attention gate units for irrelevant feature elimination, through a U-Net framework with skip connections for information compensation. The performance of fetal heart and lung segmentation indicates the superiority of our method over the existing deep learning based approaches. Our method also shows competitive performance stability during the task of semantic segmentations, showing a promising contribution on ultrasound based prognosis of congenital anomaly in the early intervention, and alleviating the negative effects caused by congenital anomaly.


Assuntos
Processamento de Imagem Assistida por Computador , Redes Neurais de Computação , Coração Fetal/diagnóstico por imagem , Pulmão/diagnóstico por imagem , Ultrassonografia
13.
Ultrason Imaging ; 43(3): 157-163, 2021 05.
Artigo em Inglês | MEDLINE | ID: mdl-33840327

RESUMO

Ultrasonic guided wave techniques have been applied to characterize cortical bone for osteoporosis assessment. Compared with the current gold-standard X-ray-based diagnostic methods, ultrasound-based techniques pose some advantages such as compactness, low cost, lack of ionizing radiation, and their ability to detect the mechanical properties of the cortex. Axial transmission technique with a source-receiver offset is employed to acquire the ultrasound data. The dispersion characteristics of the guided waves in bones are normally analyzed in the transformed domains using the dispersion curves. The transformed domain can be time-frequency map using a single channel or wavenumber-frequency (or phase velocity-frequency) map with multi-channels. In terms of acquisition effort, the first method is more cost- and time-effective than the latter. However, it remains unclear whether single-channel dispersion analysis can provide as much quantitative guided-wave information as the multi-channel analysis. The objective of this study is to compare the two methods using numerically simulated and ex vivo data of a simple bovine bone plate and explore their advantages and disadvantages. Both single- and multi-channel signal processing approaches are implemented using sparsity-constrained optimization algorithms to reinforce the focusing power. While the single-channel data acquisition and processing are much faster than those of the multi-channel, modal identification and analysis of the multi-channel data are straightforward and more convincing.


Assuntos
Osso Cortical , Ultrassom , Algoritmos , Animais , Bovinos , Osso Cortical/diagnóstico por imagem , Processamento de Sinais Assistido por Computador , Ondas Ultrassônicas , Ultrassonografia
14.
J Bone Miner Metab ; 38(1): 14-26, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-31414284

RESUMO

INTRODUCTION: Menopause can lead to osteoporosis, which is characterized by destruction of bone microstructure, poor mechanical properties, and prone to fracture. LIPUS can effectively promote bone formation and fracture healing. MSTN is a transforming growth factor-ß family member that acts as a negative regulator of skeletal muscle growth. A MSTN deficiency also has a positive effect on bone formation. However, whether LIPUS could inhibit bone loss and promote healing of bone injury of menopause through the inhibition of the MSTN signaling pathway has not been previously investigated. We herein investigated the effects of LIPUS on bone architecture, mechanical properties, the healing of bone defects, and its potential molecular mechanisms in ovariectomized rats. MATERIALS AND METHODS: The rats were randomly divided into three groups: sham ovariectomized group (Sham), ovariectomized model group (OVX), ovariectomized model with LIPUS therapy group (OVX + LIPUS). The OVX + LIPUS rats were treated with LIPUS (1.5 MHz, 30 mW/cm2) on the femur for 20 min/day that lasted for 19 days. RESULTS: LIPUS effectively improved the bone microstructure, increased mechanical properties and promoted the healing of bone defects in ovariectomized rats. Moreover, LIPUS effectively decreased the MSTN content in serum and quadriceps muscle in ovariectomized rats, and inhibited the expression of MSTN downstream signaling molecules and activated the Wnt signaling pathway in the femur. CONCLUSIONS: The present study shows that LIPUS improved osteoporosis and promoted bone defect healing in the ovariectomized rats may through the inhibition of the MSTN signal pathway.


Assuntos
Reabsorção Óssea/prevenção & controle , Miostatina/metabolismo , Ovariectomia , Transdução de Sinais , Ondas Ultrassônicas , Fosfatase Alcalina/sangue , Animais , Fenômenos Biomecânicos , Peso Corporal , Reabsorção Óssea/sangue , Feminino , Fêmur/diagnóstico por imagem , Fêmur/fisiologia , Regulação da Expressão Gênica , Fibras Musculares Esqueléticas/patologia , Músculos/patologia , Tamanho do Órgão , Ratos Sprague-Dawley , Fosfatase Ácida Resistente a Tartarato/sangue , Útero/patologia , Via de Sinalização Wnt
15.
Ultrason Imaging ; 41(5): 271-289, 2019 09.
Artigo em Inglês | MEDLINE | ID: mdl-31307317

RESUMO

The ultrasonic backscatter technique holds the promise of characterizing bone density and microstructure. This paper conducts ultrasonic backscatter parametric imaging based on measurements of apparent integrated backscatter (AIB), spectral centroid shift (SCS), frequency slope of apparent backscatter (FSAB), and frequency intercept of apparent backscatter (FIAB) for representing trabecular bone mass and microstructure. We scanned 33 bovine trabecular bone samples using a 7.5 MHz focused transducer in a 20 mm × 20 mm region of interest (ROI) with a step interval of 0.05 mm. Images based on the ultrasonic backscatter parameters (i.e., AIB, SCS, FSAB, and FIAB) were constructed to compare with photographic images of the specimens as well as two-dimensional (2D) µ-CT images from approximately the same depth and location of the specimen. Similar structures and trabecular alignments can be observed among these images. Statistical analyses demonstrated that the means and standard deviations of the ultrasonic backscatter parameters exhibited significant correlations with bone density (|R| = 0.45-0.78, p < 0.01) and bone microstructure (|R| = 0.44-0.87, p < 0.001). Some bovine trabecular bone microstructure parameters were independently associated with the ultrasonic backscatter parameters (ΔR2 = 4.18%-44.45%, p < 0.05) after adjustment for bone apparent density (BAD). The results show that ultrasonic backscatter parametric imaging can provide a direct view of the trabecular microstructure and can reflect information about the density and microstructure of trabecular bone.


Assuntos
Osso Esponjoso/anatomia & histologia , Espalhamento de Radiação , Ultrassonografia/métodos , Animais , Densidade Óssea , Bovinos , Modelos Animais
16.
Ultrason Imaging ; 40(4): 232-244, 2018 07.
Artigo em Inglês | MEDLINE | ID: mdl-29862931

RESUMO

Ultrasound measurement of the inferior vena cava (IVC) is widely implemented in the clinic. However, the process is time consuming and labor intensive, because the IVC diameter is continuously changing with respiration. In addition, artificial errors and intra-operator variations are always considerable, making the measurement inconsistent. Research efforts were recently devoted to developing semiautomated methods. But most required an initial identification of the IVC manually. As a first step toward fully automated IVC measurement, in this paper, we present an intelligent technique for automated IVC identification and localization. Forty-eight ultrasound data sets were collected from eight pigs, each of which included two frames in B-mode and color mode (C-mode) collected at the inspiration, and two cine loops in B-mode and C-mode. Static and dynamic automation algorithms were applied to the data sets for identifying and localizing the IVC. The results were evaluated by comparing with the manual measurement of experienced clinicians. The automated approaches successfully identified the IVC in 47 cases (success rate: 97.9%). The automated localization of the IVC is close to the manual counterpart, with the difference within one diameter. The automatically measured diameters are close to those measured manually, with most differences below 15%. It is revealed that the proposed method can automatically identify the IVC with high success rate and localize the IVC with high accuracy. But the study with high accuracy was conducted under good control and without considering difficult cases, which deserve future explorations. The method is a first step toward fully automated IVC measurement, which is suitable for point-of-care applications.


Assuntos
Processamento de Imagem Assistida por Computador/métodos , Ultrassonografia/métodos , Veia Cava Inferior/diagnóstico por imagem , Animais , Feminino , Modelos Animais , Suínos
17.
Sensors (Basel) ; 18(10)2018 Oct 18.
Artigo em Inglês | MEDLINE | ID: mdl-30340401

RESUMO

In this paper, a new approach to guided wave ray tomography for temperature-robust damage detection with time-of-flight (TOF) temperature compensation is developed. Based on the linear relationship between the TOF of a guided wave and temperature, analyses show that the TOF of the baseline signal can be compensated by the temperature measurement of the inspected materials without estimating the temperature compensation parameters. The inversion is based on the optimization of the TOF misfit function between the inspected and compensated baseline TOFs of the guided waves, and is applied by the elastic net penalty approach to perform thickness change mapping in a structural health monitoring (SHM) application. Experiments that are conducted in isotropic plates by piezoelectric sensors demonstrate the effectiveness of the proposed method. According to the results, our approach not only eliminates the artefacts that are caused by a temperature variation from 25 °C to 70 °C but also provides more accurate and clearer imaging of damage than conventional ray tomography methods.

18.
J Ultrasound Med ; 35(10): 2197-208, 2016 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-27562978

RESUMO

OBJECTIVES: The aim of this study was to determine the relationship between the backscattered spectral centroid shift and the bone mineral density (BMD) in vivo and investigate the feasibility of using the backscattered spectral centroid shift to characterize the cancellous bone status. METHODS: Ultrasonic backscatter measurements were performed in vivo on 1216 participants at the right calcaneus using an ultrasonic backscattered bone diagnostic system, and the backscattered spectral centroid shift was calculated at central frequencies of 3.5 and 5.0 MHz. The BMD values were measured at the sites of the lumbar spine and left hip by dual energy x-ray absorptiometry. RESULTS: The study population included 592 male and 624 female participants aged 20 to 89 years. The correlations between the backscattered spectral centroid shift in the calcaneus and the spine and hip BMD were found to be statistically significant in both the male and female groups (P < .0001). Linear regression showed that the spectral centroid shift at 3.5 MHz had negative correlations with the spine BMD (R = -0.65 for male participants; R = -0.67 for female participants) and hip BMD (R = -0.64 for male participants; R = -0.64 for female participants). The spectral centroid shift at 5.0 MHz was also found to be closely related to the spine BMD (R = -0.68 for male participants; R = -0.68 for female participants) and hip BMD (R = -0.66 for male participants; R = -0.64 for female participants). CONCLUSIONS: The moderate correlations observed between the spectral centroid shift and the spine and hip BMD demonstrate that the ultrasonic backscattered spectral centroid shift may be a useful measurement for assessment of the cancellous bone status.


Assuntos
Densidade Óssea , Calcâneo/diagnóstico por imagem , Interpretação de Imagem Assistida por Computador/métodos , Ultrassonografia/métodos , Absorciometria de Fóton , Adulto , Idoso , Idoso de 80 Anos ou mais , Estudos de Viabilidade , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Adulto Jovem
19.
J Acoust Soc Am ; 140(3): 1758, 2016 09.
Artigo em Inglês | MEDLINE | ID: mdl-27914382

RESUMO

Some pioneering studies have shown the clinical feasibility of long bones evaluation using ultrasonic guided waves. Such a strategy is typically designed to determine the dispersion information of the guided modes to infer the elastic and structural characteristics of cortical bone. However, there are still some challenges to extract multimode dispersion curves due to many practical limitations, e.g., high spectral density of modes, limited spectral resolution and poor signal-to-noise ratio. Recently, two representative signal processing methods have been proposed to improve the dispersion curves extraction. The first method is based on singular value decomposition (SVD) with advantages of multi-emitter and multi-receiver configuration for enhanced mode extraction; the second one uses linear Radon transform (LRT) with high-resolution imaging of the dispersion curves. To clarify the pros and cons, a face to face comparison was performed between the two methods. The results suggest that the LRT method is suitable to separate the guided modes at low frequency-thickness-product ( fh) range; for multimode signals in broadband fh range, the SVD-based method shows more robust performances for weak mode enhancement and noise filtering. Different methods are valuable to cover the entire fh range for processing ultrasonic axial transmission signals measured in long cortical bones.

20.
Ultrasound Med Biol ; 2024 Jun 27.
Artigo em Inglês | MEDLINE | ID: mdl-38942620

RESUMO

OBJECTIVE: To enhance the quality of low-resolution (LR) ultrasound images and mitigate artifacts and speckle noise, which can impede accurate medical diagnosis, a novel method called the dual frequency-domain guided adaptation model (DF-GAM) is proposed. The method aims to achieve high-quality image reconstruction across diverse domains, including different ultrasound machines, diseases and phantom images. METHODS: DF-GAM utilizes a dual-branch network architecture combined with frequency-domain self-adaptation and self-supervised edge regression. This approach enables cross-domain enhancement by focusing on the reconstruction of clear tissue structures and speckle patterns. The model is designed to adapt to various ultrasound imaging (USI) scenarios, ensuring its applicability in real-world clinical settings. RESULTS: Experimental evaluations of DF-GAM were conducted using five different datasets. The results demonstrated the method's effectiveness, with DF-GAM outperforming existing enhancement techniques. The average peak signal-to-noise ratio (PSNR) achieved was 34.62, and the structural similarity index (SSIM) was 0.91, indicating a significant improvement in image quality compared to other methods. CONCLUSION: DF-GAM shows great potential in improving medical image diagnosis and interpretation. Its ability to enhance LR ultrasound images across various domains without the need for extensive training data makes it a valuable tool for clinical use. The high PSNR and SSIM scores validate the method's effectiveness, suggesting that DF-GAM could significantly contribute to the field of USI diagnostics.

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