Accelerated magnetic resonance imaging using the sparsity of multi-channel coil images.

Joint estimation of coil sensitivities and output image (JSENSE) is a promising approach that improves the reconstruction of parallel magnetic resonance imaging (pMRI). However, when acceleration factor increases, the signal to noise ratio (SNR) of JSENSE reconstruction decreases as quickly as that of the conventional pMRI. Although sparse constraints have been used to improve the JSENSE reconstruction in recent years, these constraints only use the sparsity of the output image, which cannot fully exploit the prior information of pMRI.

A novel microfluidic chip for assessing dynamic adhesion behavior of cell-targeting microbubbles.

The primary aim of this study was to develop a microfluidic chip to study the dynamic adhesion behavior of cell-targeted microbubbles. The microfluidic device is composed of polydimethylsiloxane and is fabricated using the soft lithography technique. Each chamber of the microfluidic chip comprises eight U-shaped microsieves, by which various flow velocity distributions are generated.

Computer-assisted assessment of ultrasound real-time elastography: initial experience in 145 breast lesions.

Purpose: To develop and evaluate a computer-assisted method of quantifying five-point elasticity scoring system based on ultrasound real-time elastography (RTE), for classifying benign and malignant breast lesions, with pathologic results as the reference standard.

Materials And Methods: Conventional ultrasonography (US) and RTE images of 145 breast lesions (67 malignant, 78 benign) were performed in this study. Each lesion was automatically contoured on the B-mode image by the level set method and mapped on the RTE image.

Surface roughness detection of arteries via texture analysis of ultrasound images for early diagnosis of atherosclerosis.

There is a strong research interest in identifying the surface roughness of the carotid arterial inner wall via texture analysis for early diagnosis of atherosclerosis. The purpose of this study is to assess the efficacy of texture analysis methods for identifying arterial roughness in the early stage of atherosclerosis. Ultrasound images of common carotid arteries of 15 normal mice fed a normal diet and 28 apoE(-/-) mice fed a high-fat diet were recorded by a high-frequency ultrasound system (Vevo 2100, frequency: 40 MHz).

Ultrasound contrast image segmentation using a modified level set method.

Manual segmentation of ultrasound contrast images is time-consuming and inevitable to variability, and computer-based segmentation algorithms often require user interaction. This paper proposes a novel level set model for fully automated segmentation of vascular ultrasound contrast images. The initial contour of arterial boundaries is acquired based on an automatic procedure.

Quantitative analysis of peri-tumor tissue elasticity based on shear-wave elastography for breast tumor classification.

For shear-wave elastography (SWE) images, the most common site of tumor-associated stiffness is generally in the surrounding stroma rather than the tumor itself. The aim of this study is to assess the value of the peri-tumor tissue elasticity in the classification of breast tumors. SWE images of 106 breast tumors (65 benign, 41 malignant) were collected from 82 consecutive patients.

Open system for micro-ultrasound.

Micro-ultrasound is able to delineate small structures with fine spatial resolution on the order of several tens of microns. It is an invaluable imaging tool for many clinical and preclinical applications. This paper presents the development of an open system for various biomedical studies.

A novel cationic microbubble coated with stearic acid-modified polyethylenimine to enhance DNA loading and gene delivery by ultrasound.

A novel cationic microbubble (MB) for improvement of the DNA loading capacity and the ultrasound-mediated gene delivery efficiency has been developed; it has been prepared with commercial lipids and a stearic acid modified polyethylenimine 600 (Stearic-PEI600) polymer synthesized via acylation reaction of branched PEI600 and stearic acid mediated by N, N'-carbonyldiimidazole (CDI). The MBs' concentration, size distribution, stability and zeta potential (ζ-potential) were measured and the DNA loading capacity was examined as a function of the amount of Stearic-PEI600. The gene transfection efficiency and cytotoxicity were also examined using breast cancer MCF-7 cells via the reporter plasmid pCMV-Luc, encoding the firefly luciferase gene.

Plasmonic scissors for molecular design.

Heterogeneous catalysts play an important role in surface catalytic reactions, but selective bond breaking and control of reaction products in catalytic processes remain significant challenges. High-vacuum tip-enhanced Raman spectroscopy (HV-TERS) is one of the best candidates to realize surface catalytic reactions. Herein, HV-TERS was employed in a new method to control dissociation by using hot electrons, generated from plasmon decay, as plasmonic scissors.

Rigid nanoparticle-based delivery of anti-cancer siRNA: challenges and opportunities.

Gene therapy is a promising strategy to treat various genetic and acquired diseases. Small interfering RNA (siRNA) is a revolutionary tool for gene therapy and the analysis of gene function. However, the development of a safe, efficient, and targetable non-viral siRNA delivery system remains a major challenge in gene therapy.

Real-time 3-dimensional contrast-enhanced ultrasound in detecting hemorrhage of blunt renal trauma.

Objectives: The objective of this study is to evaluate the diagnostic value of real-time 3-dimensional contrast-enhanced ultrasound in the hemorrhage of blunt renal trauma.

Methods: Eighteen healthy New Zealand white rabbits were randomly divided into 3 groups. Blunt renal trauma was performed on each group by using minitype striker.

Impact of multiple cardiovascular risk factors on carotid intima-media thickness and elasticity.

Background: Carotid intima-media thickness (IMT) and elasticity have been shown to be independent predictors of cardiovascular disease (CVD). Cardiovascular risk factors (CVRFs) includes hypertension, dyslipidemia, diabetes, overweight and smoking. The objective was to investigate whether the clustering of three or more components of CVRFs has a greater impact on carotid IMT and elasticity than individual components of CVRFs.

Electric field gradient quadrupole Raman modes observed in plasmon-driven catalytic reactions revealed by HV-TERS.

Electric field gradient quadrupole Raman modes are observed in plasmon-driven chemical reactions investigated with high vacuum tip-enhanced Raman spectroscopy (HV-TERS). TER spectra reveal that 4-nitrobenzenethiol (4NBT) catalytically dimerizes to dimercaptoazobenzene (DMAB) under an HV-TERS setup. More importantly, we find that the electric field gradient leads to strong enhancement of the infrared (IR)-active modes of DMAB.

Strain estimation in elastography using scale-invariant keypoints tracking.

This paper proposes a novel strain estimator using scale-invariant keypoints tracking (SIKT) for ultrasonic elastography. This method is based on tracking stable features between the pre- and post-compression A-lines to obtain tissue displacement estimates. The proposed features, termed scaleinvariant keypoints, are independent of signal scale change according to the scale-space theory, and therefore can preserve their patterns while undergoing a substantial range of compression.

Blind-deconvolution optical-resolution photoacoustic microscopy in vivo.

Optical-resolution photoacoustic microscopy (OR-PAM) is becoming a vital tool for studying the microcirculation system in vivo. By increasing the numerical aperture of optical focusing, the lateral resolution of OR-PAM can be improved; however, the depth of focus and thus the imaging range will be sacrificed correspondingly. In this work, we report our development of blind-deconvolution optical-resolution photoacoustic microscopy (BD-PAM) that can provide a lateral resolution ~2-fold finer than that of conventional OR-PAM (3.

Insights into the nature of plasmon-driven catalytic reactions revealed by HV-TERS.

The nature of plasmon-driven chemical reactions is experimentally investigated using high vacuum tip-enhanced Raman spectroscopy (HV-TERS). It is revealed that the coupling between the tip and the substrate can produce intense plasmon resonance, which then decays to produce sufficient hot electrons and thus catalyses the chemical reaction. The photoelectron emission from the laser illuminated silver substrate alone cannot drive the reaction.

A novel modulated excitation imaging system for microultrasound.

Microultrasound (micro-US), also known as ultrasound biomicroscope, is able to delineate small structures with fine spatial resolution. However, micro-US suffers limited depth of penetration due to significantly large attenuation at high frequencies. Modulated excitation imaging has displayed the capability to improve the penetration depth, while maintaining the spatial resolution.

Paclitaxel-liposome-microbubble complexes as ultrasound-triggered therapeutic drug delivery carriers.

Liposome-microbubble complexes (LMC) have become a promising therapeutic carrier for ultrasound-triggered drug delivery to treat malignant tumors. However, the efficacy for ultrasound-assisted chemotherapy in vivo and the underlying mechanisms remain to be elucidated. Here, we investigated the feasibility of using paclitaxel-liposome-microbubble complexes (PLMC) as possible ultrasound (US)-triggered targeted chemotherapy against breast cancer.

Targeted delivery of GDNF through the blood-brain barrier by MRI-guided focused ultrasound.

Neurotrophic factors, such as glial cell line-derived neurotrophic factor (GDNF), are promising therapeutic agents for neurodegenerative diseases. However, the application of GDNF to treat these diseases effectively is limited because the blood-brain barrier (BBB) prevents the local delivery of macromolecular therapeutic agents from entering the central nervous system (CNS). Focused ultrasound combined with microbubbles (MBs) using appropriate parameters has been previously demonstrated to be able to open the BBB locally and noninvasively.

A flexible annular-array imaging platform for micro-ultrasound.

Micro-ultrasound is an invaluable imaging tool for many clinical and preclinical applications requiring high resolution (approximately several tens of micrometers). Imaging systems for micro-ultrasound, including single-element imaging systems and linear-array imaging systems, have been developed extensively in recent years. Single-element systems are cheaper, but linear-array systems give much better image quality at a higher expense.

Codopant ion-induced tunable upconversion emission in β-NaYF4:Yb3+/Tm3+ nanorods.

An innovative route to tune upconversion (UC) emission in β-NaYF(4):Yb(3+)/Tm(3+) nanorods through codoping a third rare-earth ion upon continuous wave excitation near 976 nm is reported. The dependence of UC emission on codopant concentration and environment temperature shows that tailored local environment and readjustable depopulation of excited-state ions are responsible for the tuning of UC luminescence. Codopant ions introduce a new distribution of active ions and a modified distance between Tm(3+) and Yb(3+) ions, making UC systems more sensitive to impurity ions than downconversion systems.

In-situ plasmon-driven chemical reactions revealed by high vacuum tip-enhanced Raman spectroscopy.

With strong surface plasmons excited at the metallic tip, tip-enhanced Raman spectroscopy (TERS) has both high spectroscopic sensitivity and high spatial resolution, and is becoming an essential tool for chemical analysis. It is a great challenge to combine TERS with a high vacuum system due to the poor optical collection efficiency. We used our innovatively designed home-built high vacuum TERS (HV-TERS) to investigate the plasmon-driven in-situ chemical reaction of 4-nitrobenzenethiol dimerizing to dimercaptoazobenzene.

3.0T whole-heart coronary magnetic resonance angiography performed with 32-channel cardiac coils: a single-center experience.

Background: Whole-heart coronary magnetic resonance angiography (MRA) is a promising method for noninvasive, radiation-free detection and exclusion of obstructive coronary artery disease; however, the required imaging time and robustness of the technique are not yet satisfactory. We evaluated the value of whole-heart coronary MRA at 3.0T using a 32-channel cardiac coil, which reduces image-acquisition times and hence allows to increase the clinical throughput.

A 2D non-invasive ultrasonic method for simultaneous measurement of arterial strain and flow pattern.

Introduction: Many cardiovascular diseases are closely associated with the mechanical properties of arterial wall and hemodynamic parameters. Simultaneous measurements of the arterial strain and flow pattern may aid diagnosis of cardiovascular diseases and may be useful to study fluid-structure interaction between blood and vessel. This paper proposes a 2D non-invasive ultrasonic method to simultaneously measure arterial strain and flow pattern with sub-pixel accuracy.

Transportation of single cell and microbubbles by phase-shift introduced to standing leaky surface acoustic waves.

A microfluidic device was developed to precisely transport a single cell or multiple microbubbles by introducing phase-shifts to a standing leaky surface acoustic wave (SLSAW). The device consists of a polydimethyl-siloxane (PDMS) microchannel and two phase-tunable interdigital transducers (IDTs) for the generation of the relative phase for the pair of surface acoustic waves (SAW) propagating along the opposite directions forming a standing wave. When the SAW contacts the fluid medium inside the microchannel, some of SAW energy is coupled to the fluid and the SAW becomes the leaky surface wave.