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Accurate diagnosis of non-alcoholic steatohepatitis (NASH) is a critical issue in current clinical practice. Non-invasive diagnosis of NASH can be achieved by quantitative ultrasound (QUS), which requires a detailed understanding tissue-specific acoustic microstructure at cellular scale (i.e., 10 μm). Therefore, QUS methods would benefit from the knowledge of the acoustic properties of organelles...
Ultrasound elastography is an effective modality for the delineation of thermally ablated regions after liver tumor treatments. Image contrast in elasticity imaging is based on differences in the Young's modulus of local tissue. In this work, we compare our previously introduced electrode displacement elastography (EDE) with a commercially available acoustic radiation force impulse imaging (ARFI)...
Acoustic Angiography enables high resolution and high SNR imaging of microbubble contrast agents. The technique relies on pulsing and receiving at two widely separated acoustic bandwidths to reject signal from the tissue. To date this technique has been used to evaluate microvasculature within tumors and kidneys, but has not been used to visualize in vivo blood flow within heart, or liver. These targets...
Point shear wave elastography (pSWE) provides noninvasive measures of mechanical stiffness of biological tissue. Over the past decade, research has demonstrated that pSWE is effective at diagnosing a multitude of pathologies such as liver fibrosis and cancer. Life science researchers stand to benefit tremendously from access to pSWE but a number of challenges have limited its use in small animals...
An effective imaging modality to delineate ablated regions after microwave ablation (MWA) therapy is crucial to yield successful treatment outcomes. Ultrasound B-mode imaging is widely used to guide the ablation antenna placement. However, the image quality suffers from relatively low imaging contrast due to the similar echogenicity between the ablated and surrounding tissue. In this study, we applied...
It is highly desirable to monitor microwave ablation (MWA) treatments noninvasively for substantially improving the clinical implementation of MWA procedures and progress toward full clinical uses worldwide. This paper explored the feasibility of using ultrasonic Nakagami imaging to evaluate the thermal lesion induced by microwave ablation (MWA) in porcine liver. 2-D RF data backscattered from the...
Transarterial chemoembolization (TACE) is standard of care for patients with Barcelona Clinic Liver Cancer stage B hepatocellular carcinoma (HCC). Current guidelines recommend follow-up imaging 4–6 weeks after treatment. An earlier indicator of residual disease would enable clinicians to retreat sooner, potentially improving disease control. In this study, time-intensity curves from 3D contrast-enhanced...
Current liver cancer ablation methods are mainly thermal-based and inherently exhibit inconsistent tissue ablation due to irregular heat dissipation. Histotripsy is a non-thermal ultrasound (US) ablation method that fractionates tissue through the precise control of acoustic cavitation. This paper studies the feasibility and chronic effects of non-invasive histotripsy for liver cancer ablation in...
A novel hundred-microsecond histotripsy treatment method is proposed. This method utilizes the confocal dual-frequency of second harmonic superimposition control approach. A custom-designed transducer consisting of two confocal spherical-annular element arrays is used. The frequencies of the transducer are 1.1 and 2.2 MHz, and the peak negative pressures are 5 MPa and 12 MPa with shock wave. Due to...
Liver fibrosis is the common result of chronic liver disease. Diagnosis and grading liver fibrosis for patient management is mainly based on blood tests and hepatic puncture-biopsy, which is particularly invasive. Quantitative UltraSound (QUS) techniques provide insight into tissue microstructure and are based on the frequency-based analysis of the signals from biological tissues. This study aims...
Vascular remodeling agents that can enhance the effects of chemotherapy have gained significant attention. However, timing and dosing of combinatory treatment regimens requires longitudinal biomarkers to optimize regimens on a patient-by-patient basis. 3D dynamic contrast-enhanced ultrasound (DCE-US) has been proposed as an inexpensive bedside tool to longitudinally guide dosing and scheduling of...
Nonalcoholic fatty liver disease (NAFLD) is the most common cause of chronic liver disease and can often lead to fibrosis, cirrhosis, cancer and complete liver failure. Liver biopsy is the current standard of care to quantify hepatic steatosis but it comes with increased patient risk and only samples a small portion of the liver. Imaging approaches to assess NAFLD include proton density fat fraction...
There are two generally used ultrasonic approaches to extract sets of quantitative parameters: the Lizzi-Feleppa (LF) and quantitative ultrasound (QUS) approaches. The LF approach estimates LF parameters from the linear fit of the backscatter coefficient (BSC), and yields slope, intercept and midband. The QUS approach relies on the attenuation coefficient (AC) and BSC versus frequency, and yields...
Quantitative ultrasound parameter estimates from the Lizzi-Feleppa (LF slope, intercept and midband) and quantitative ultrasound (mean BSC, mean AC, ESD and EAC) approaches were compared for in vivo and ex vivo mouse liver fat content monitoring. The quantitative ultrasound parameters having the higher correlations with fat content were EAC (R2=0.68), mean BSC (R2=0.60), mean AC (R2=0.60) and LF midband...
Targeting the ultrasound beam and predicting the thermal coagulation in advance are important for high-intensity focused ultrasound (HIFU) treatment. Cavitation bubbles are known to enhance ultrasonic heating, however, temporal and spatial control of their generation is not simple. In our previous study, a method utilizing acoustic radiation force to predict thermal coagulation was suggested. In this...
Early detection of pathological processes is crucial for the prognosis and treatment of patients, which can be facilitated through studying tissue biomechanical properties. Shear wave elastography is a technique to estimate the shear modulus of tissue. Such measurements quantify elasticity linearized around an immediate state of local stress condition, under applied nature of excitation. Stress-strain...
Diagnosis and assessment of liver fibrosis grade required for management is mainly based on blood tests and invasive hepatic puncture-biopsy. Quantitative UltraSound (QUS) techniques provide insight into tissue microstructure and are based on the frequency-based analysis of the signals from biological tissues. This study aims to explore the diagnostic performance of QUS technique in high frequency...
Shear Wave Elasticity Imaging is used to assess liver fibrosis, as shear wave speed (SWS) correlates with fibrosis stage. We have previously proposed a group SWS-based method to derive the tissue's stiffness (μ) and viscosity (η) using an analytic solution for the shear wave propagation in a Voigt material which accounts for the source excitation geometry [Rouze et al., IEEE IUS 2016]. However, in...
For many routine surgeries and procedures, such as liver biopsies, obese patients present an increased challenge. In liver biopsies, it is more difficult to visualize the needle tip in realtime abdominal ultrasound images, particularly when multiple layers of fat and other tissues obscure needle localization, which results in multiple needle passes to obtain an adequate biopsy sample. This work aims...
A challenge in the clinical application of shear wave elastography is the level of measurement variance or noise compared to clinically significant changes in shear wave speed. For instance, liver fibrosis staging is challenged by the relatively high variance of shear wave velocity estimates in comparison to the modulus difference between early (F1-F3) fibrosis stages. Recent work has shown that ultrasound...
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