An Acoustic Meta-Skin Insulator.

Acoustic metamaterials with artificial microstructures are attractive to realize intriguing functions, including efficient waveguiding, which requires large impedance mismatches to realize total side reflection with negligible transmission and absorption. While large impedance mismatch can be readily realized in an air environment, acoustic waveguiding in an underwater environment remains elusive due to insufficient impedance mismatch of state-of-the-art metamaterials. Here, a superhydrophobic acoustic metasurface of microstructured poly(vinylidene fluoride) membrane, referred to as a "meta-skin" insulator, which is able to confine acoustic waves in an all-angle and wide spectrum range due to tremendous impedance mismatch at stable air/water interfaces, viz.

A GPU-accelerated fully 3D OSEM image reconstruction for a high-resolution small animal PET scanner using dual-ended readout detectors.

In this work, a GPU-accelerated fully 3D ordered-subset expectation maximization (OSEM) image reconstruction with point spread function (PSF) modeling was developed for a small animal PET scanner with a long axial field of view (FOV). Dual-ended readout detectors that provided high depth of interaction (DOI) resolution were used for the small animal PET scanner to simultaneously achieve uniform high spatial resolution and high sensitivity. First, we developed a novel sinogram generation method, in which the dimension of the sinogram was determined first and then an event was assigned to a few neighboring sinogram elements by using weights that are inversely proportional to the distance from the measured line of response (LOR) to the LOR of the sinogram elements.

Obtaining PET/CT images from non-attenuation corrected PET images in a single PET system using Wasserstein generative adversarial networks.

Positron emission tomography (PET) imaging plays an indispensable role in early disease detection and postoperative patient staging diagnosis. However, PET imaging requires not only additional computed tomography (CT) imaging to provide detailed anatomical information but also attenuation correction (AC) maps calculated from CT images for precise PET quantification, which inevitably demands that patients undergo additional doses of ionizing radiation. To reduce the radiation dose and simultaneously obtain high-quality PET/CT images, in this work, we present an alternative based on deep learning that can estimate synthetic attenuation corrected PET (sAC PET) and synthetic CT (sCT) images from non-attenuation corrected PET (NAC PET) scans for whole-body PET/CT imaging.

Ultrasonic microstreaming for complex-trajectory transport and rotation of single particles and cells.

Precisely controllable transport and rotation of microparticles and cells has great potential to enable new capabilities for single-cell level analysis. In this work, we present versatile ultrasonic microstreaming based manipulation that enables active and precise control of transport and rotation of individual microscale particles and biological cells in a microfluidic device. Two different types of ultrasonic microstreaming flow patterns can be produced by oscillating embedded microstructures in circular and rectilinear vibration modes, which have been validated by both numerical simulation and experimental observation.

Arterial culprit plaque characteristics revealed by magnetic resonance Vessel Wall imaging in patients with single or multiple infarcts.

Purpose: To investigate characteristics of intra- and extracranial arterial culprit plaques between patients with single infarct and multiple-infarcts by a head-neck combined high resolution magnetic resonance vessel wall imaging (HR-MRVWI).

Materials And Methods: Forty-three patients with recent ischemic stroke due to large artery atherosclerosis were enrolled. The head-neck combined HR-MRVWI was performed in all patients both pre- and post-contrast administration.

Development and External Validation of Radiomics Approach for Nuclear Grading in Clear Cell Renal Cell Carcinoma.

Background And Purpose: Nuclear grades of clear cell renal cell carcinoma (ccRCC) are usually confirmed by invasive methods. Radiomics is a quantitative tool that uses non-invasive medical imaging for tumor diagnosis and prognosis. In this study, a radiomics approach was proposed to analyze the association between preoperative computed tomography (CT) images and nuclear grades of ccRCC.

Targeted imaging of orthotopic prostate cancer by using clinical transformable photoacoustic molecular probe.

Background: To obtain high-yield histological samples by targeted prostate cancer (PCa) biopsy is the current trend compared with transrectal ultrasound (TRUS)-guided systematic histological biopsy, which is regarded as the gold standard for prostate cancer (PCa) diagnosis. In this paper, we present a targeted PCa imaging strategy using a real-time molecular photoacoustic imaging system integrated with a handheld US probe (PAI/US) and synthesized an integrin αβ targeted probe based on ICG (cRGD-ICG).

Methods: To prepare cRGD-ICG, ICG-NHS was linked to cRGD through carboxyl-co-reaction.

Fiber-Based Clock Synchronization Method for Medical Ultrasound System.

Brain ultrasound has attracted great attention recently due to its noninvasive treatment function for brain diseases. However, ultrasound is still difficult to pass through an intact skull. Phase correction is recognized as an effective method for skull compensation.

Activatable NIR-II photoacoustic imaging and photochemical synergistic therapy of MRSA infections using miniature Au/Ag nanorods.

Multidrug-resistant Staphylococcus aureus (MRSA) seriously endanger human health. The development of efficient methods to eliminate the infections and monitor the treatment process are of great significance. Near-infrared-II (NIR-II) photoacoustic (PA) imaging and photothermal therapy (PTT) are highly integrated theranostic platforms with superior performance including a low imaging background, increased tissue penetration depth, and high photothermal threshold.

Non-invasive ultrasonic neuromodulation of neuronal excitability for treatment of epilepsy.

Non-invasive low-intensity pulsed ultrasound has been employed for direct neuro-modulation. However, its range and effectiveness for different neurological disorders have not been fully elucidated. We used multiple approaches of electrophysiology, immunohistochemistry, and behavioral tests as potential epilepsy treatments in non-human primate model of epilepsy and human epileptic tissues.

Artifact removal using a hybrid-domain convolutional neural network for limited-angle computed tomography imaging.

The suppression of streak artifacts in computed tomography with a limited-angle configuration is challenging. Conventional analytical algorithms, such as filtered backprojection (FBP), are not successful due to incomplete projection data. Moreover, model-based iterative total variation algorithms effectively reduce small streaks but do not work well at eliminating large streaks.

Ultrasound Neuromodulation Inhibits Seizures in Acute Epileptic Monkeys.

Ultrasound stimulation has recently emerged as a non-invasive method for modulating brain activity in animal and human studies with healthy subjects. Whether brain diseases such as Alzheimer's disease, epilepsy, and depression can be treated using ultrasound stimulation still needs to be explored. Recent studies have reported that ultrasound stimulation suppressed epileptic seizures in a rodent model of epilepsy.

Quantitative Estimation of Passive Elastic Properties of Individual Skeletal Muscle in Vivo Using Normalized Elastic Modulus-Length Curve.

Precise characterization of the passive elastic properties of human skeletal muscle could provide valuable information for functional assessment and medical diagnosis. Using normalized elastic modulus-length curve based on a piecewise exponential model, a non-invasive ultrasonography (US) method was developed for estimating three physiologically meaningful parameters, termed as passive-elastic coefficient k, slack length l and slack elastic modulus G, to quantify the passive elastic properties of human gastrocnemius (GM) muscle, and correlate different findings with healthy and atrophic subjects. Dynamic B-mode US and shear wave elastography (SWE) videos of right GM muscles were performed in 32 healthy subjects and 18 atrophic patients with their ankle angles from 40° plantarflexion to 30° dorsiflexion by an isokinetic dynamometer.

Real-time volumetric MR thermometry using 3D echo-shifted sequence under an open source reconstruction platform.

Purpose: The aim of this work is to implement real-time 3D MR thermometry for high intensity focused ultrasound (HIFU) monitoring.

Methods: Volumetric MR thermometry was implemented based on a 3D echo-shifted sequence with short TR to improve temperature sensitivity. The 3D acquisition was accelerated in two phase encoding directions with controlled aliasing in volumetric parallel imaging (CAIPIRINHA).

Dual phase grating based X-ray differential phase contrast imaging with source grating: theory and validation.

In this work, we developed a new theoretical framework using wave optics to explain the working mechanism of the grating based X-ray differential phase contrast imaging (XPCI) interferometer systems consist of more than one phase grating. Under the optical reversibility principle, the wave optics interpretation was simplified into the geometrical optics interpretation, in which the phase grating was treated as a thin lens. Moreover, it was derived that the period of an arrayed source, e.

ADAPTIVE-NET: deep computed tomography reconstruction network with analytical domain transformation knowledge.

Background: Recently, the paradigm of computed tomography (CT) reconstruction has shifted as the deep learning technique evolves. In this study, we proposed a new convolutional neural network (called ADAPTIVE-NET) to perform CT image reconstruction directly from a sinogram by integrating the analytical domain transformation knowledge.

Methods: In the proposed ADAPTIVE-NET, a specific network layer with constant weights was customized to transform the sinogram onto the CT image domain via analytical back-projection.

Noninvasive ultrasound deep brain stimulation of nucleus accumbens induces behavioral avoidance.

Ultrasound stimulation is an emerging noninvasive option in treating neuropsychiatric disorders. The present study investigates the behavioral alterations resulting from ultrasound stimulation on the nucleus accumbens (NAc) in freely moving mice. Our results show that an acute ultrasound stimulation on the NAc, rather than the visual cortex or auditory cortex, led to a pronounced avoidance behavior, while repeated NAc ultrasound stimulation resulted in an obvious conditioned place aversion with changes in synaptic protein (GluA1/2 subunit) expression.

Automatic left ventricle segmentation from cardiac magnetic resonance images using a capsule network.

Purpose: Segmentation of magnetic resonance images (MRI) of the left ventricle (LV) plays a key role in quantifying the volumetric functions of the heart, such as the area, volume, and ejection fraction. Traditionally, LV segmentation is performed manually by experienced experts, which is both time-consuming and prone to subjective bias. This study aims to develop a novel capsule-based automated segmentation method to automatically segment the LV from images obtained by cardiac MRI.

New Sm-PMN-PT Ceramic-Based 2-D Array for Low-Intensity Ultrasound Therapy Application.

A two-dimensional (2-D) array with a small pitch (approximately 0.5λ in medium) can achieve complete 3-D control of ultrasound beams without grating lobes and enable the generation of multiple focal spots simultaneously, which is a desired tool for noninvasive therapy. However, the large electrical impedance of 2-D array elements owing to their small size results in a low energy transfer efficiency between a 2-D array and an electrical system, thereby limiting their practical applications.

Three-dimensional intra- and extracranial arterial vessel wall joint imaging in patients with cerebrovascular disease.

Purpose: To evaluate the clinical performance of a newly developed three-dimensional (3D) intra- and extracranial arterial vessel wall joint imaging technique at 3T using T1-weighted 3D variable-flip-angle turbo spin-echo sequence with improved cerebrospinal fluid suppression in patients with cerebrovascular disease.

Materials And Methods: 122 consecutive patients (mean age 45.96 ± 12.

Hot electron and thermal effects in plasmonic catalysis of nanocrystal transformation.

Plasmonic metal nanoparticles have the ability to harvest visible light and cause effective energy conversion, and they are considered as promising catalysts to drive chemical reactions. Although plasmonic catalysis has been widely used to mediate the reaction of organic molecules, the mechanism of contribution of thermal and hot carriers remains unclear. The catalysis of hot carriers is normally proposed as the dominant role of plasmonic catalysis, while the contribution of plasmonic thermal effects is often ignored, since the molecules on the metal surface are unstable at high temperatures.

Ultrasound Stimulation of Periaqueductal Gray Induces Defensive Behaviors.

Low-intensity focused ultrasound stimulation (LIFUS) has the potential to noninvasively penetrate the intact skull and to modulate neural activity in the cortex and deep brain nuclei. The midbrain periaqueductal gray (PAG) is associated with the generation of defensive behaviors. The aim of this study was to examine whether LIFUS of the PAG induced defensive behaviors in mice.

Multi-plasmon resonances enhanced two-photon coherent anti-Stokes Raman scattering by nanorods.

The development of new structures allows two-photon coherent anti-Stokes Raman scattering (TPCARS) to be strongly enhanced by multiple surface plasmon resonances (MSPRs). In this paper, plasmonic structure consisting of two Ag nanorods is designed and the enhancement of TPCARS is investigated. By properly selecting designing structure parameters, strong MSPRs peaks at 1020 nm and 505 nm are obtained, which can enhance the TPCARS signal based on the frequency match of the fundamental frequency and frequency doubling.

DeepcomplexMRI: Exploiting deep residual network for fast parallel MR imaging with complex convolution.

This paper proposes a multi-channel image reconstruction method, named DeepcomplexMRI, to accelerate parallel MR imaging with residual complex convolutional neural network. Different from most existing works which rely on the utilization of the coil sensitivities or prior information of predefined transforms, DeepcomplexMRI takes advantage of the availability of a large number of existing multi-channel groudtruth images and uses them as target data to train the deep residual convolutional neural network offline. In particular, a complex convolutional network is proposed to take into account the correlation between the real and imaginary parts of MR images.

Multi-View Mammographic Density Classification by Dilated and Attention-Guided Residual Learning.

Breast density is widely adopted to reflect the likelihood of early breast cancer development. Existing methods of mammographic density classification either require steps of manual operations or achieve only moderate classification accuracy due to the limited model capacity. In this study, we present a radiomics approach based on dilated and attention-guided residual learning for the task of mammographic density classification.