A pilot study of cardiac guided wave elastography: An testing in a rodent model with mechanical testing validation.

Many heart diseases can change the elasticity of myocardial tissues, making elastography a potential medical imaging strategy for heart disease diagnosis and cardiovascular risk assessment. Among the existing elastography methods, ultrasound elastography is an appealing choice because of ultrasound's inherent advantages of low cost, high safety, wide availability, and deep penetration. The existing investigations of cardiac ultrasound elastography were implemented based on a bulk model of heart tissue, treating the waves generated in the myocardial tissues as shear waves.

Regulating interparticle proximity in plasmonic nanosphere aggregates to enhance photoacoustic response and photothermal stability.

Designing plasmonic nanoparticles for biomedical photoacoustic (PA) imaging involves tailoring material properties at the nanometer scale. A key in developing plasmonic PA contrast nanoagents is to engineer their enhanced optical responses in the near-infrared wavelength range, as well as heat transfer properties and photostability. This study introduces anisotropic plasmonic nanosphere aggregates with close interparticle proximity as photostable and efficient contrast agent for PA imaging.

Laser-activated perfluorocarbon nanodroplets for intracerebral delivery and imaging via blood-brain barrier opening and contrast-enhanced imaging.

Background: Ultrasound and photoacoustic (US/PA) imaging is a promising tool for in vivo visualization and assessment of drug delivery. However, the acoustic properties of the skull limit the practical application of US/PA imaging in the brain. To address the challenges in targeted drug delivery to the brain and transcranial US/PA imaging, we introduce and evaluate an intracerebral delivery and imaging strategy based on the use of laser-activated perfluorocarbon nanodroplets (PFCnDs).

Magnetically Steered Cell Therapy For Functional Restoration Of Intraocular Pressure Control In Open-Angle Glaucoma.

Unlabelled: Trabecular meshwork (TM) cell therapy has been proposed as a next-generation treatment for elevated intraocular pressure (IOP) in glaucoma, the most common cause of irreversible blindness. Using a magnetic cell steering technique with excellent efficiency and tissue-specific targeting, we delivered two types of cells into a mouse model of glaucoma: either human adipose-derived mesenchymal stem cells (hAMSCs) or induced pluripotent cell derivatives (iPSC-TM cells). We observed a 4.

Coupling Gold Nanospheres into Nanochain Constructs for High-Contrast, Longitudinal Photoacoustic Imaging.

Structural parameters play a crucial role in determining the electromagnetic and thermal responses of gold nanoconstructs (GNCs) at near-infrared (NIR) wavelengths. Therefore, developing GNCs for reliable, high-contrast photoacoustic imaging has been focused on adjusting structural parameters to achieve robust NIR light absorption with photostability. In this study, we introduce an efficient photoacoustic imaging contrast agent: gold sphere chains (GSCs) consisting of plasmonically coupled gold nanospheres.

Tunable Interparticle Connectivity in Gold Nanosphere Assemblies for Efficient Photoacoustic Conversion.

Manipulating matter at the nanometer scale to create desired plasmonic nanostructures holds great promise in the field of biomedical photoacoustic (PA) imaging. We demonstrate a strategy for regulating PA signal generation from anisotropic nano-sized assemblies of gold nanospheres (Au NSs) by adjusting the inter-particle connectivity between neighboring Au NSs. The inter-particle connectivity is controlled by modulating the diameter and inter-particle spacing of Au NSs in the nanoassemblies.

Applications of the Photocatalytic and Photoacoustic Properties of Gold Nanorods in Contrast-Enhanced Ultrasound and Photoacoustic Imaging.

The applications of ultrasound imaging are often limited due to low contrast, which arises from the comparable acoustic impedance of normal tissues and disease sites. To improve the low contrast, we propose a contrast agent called gas-generating laser-activatable nanorods for contrast enhancement (GLANCE), which enhances ultrasound imaging contrast in two ways. First, GLANCE absorbs near-infrared lasers and generates nitrogen gas bubbles through the photocatalytic function of gold nanorods and photolysis of azide compounds.

Hyper-Branched Gold Nanoconstructs for Photoacoustic Imaging in the Near-Infrared Optical Window.

In plasmonic nanoconstructs (NCs), fine-tuning interparticle interactions at the subnanoscale offer enhanced electromagnetic and thermal responses in the near-infrared (NIR) wavelength range. Due to tunable electromagnetic and thermal characteristics, NCs can be excellent photoacoustic (PA) imaging contrast agents. However, engineering plasmonic NCs that maximize light absorption efficiency across multiple polarization directions, i.

Photoacoustic Monitoring of Stem Cell Location and Apoptosis with Caspase-3-Responsive Nanosensors.

Stem cell therapy has immense potential in a variety of regenerative medicine applications. However, clinical stem cell therapy is severely limited by challenges in assessing the location and functional status of implanted cells . Thus, there is a great need for longitudinal, noninvasive stem cell monitoring.

Photoacoustic-guided ultrasound thermal imaging without prior knowledge of tissue composition.

Thermal strain imaging (TSI) is a widely investigated ultrasound (US) thermometry technique that is based on the temperature-dependent change in speed of sound. However, a major challenge of TSI is a calibration process to account for material-dependent thermal strain. In this study, we leverage nanoparticle (NP)-mediated photoacoustic (PA) thermometry to calibrate thermal strain and guide US thermal imaging.

Fluorescence-informed photoacoustic discrimination of multiple chromophores by lifetime mapping optically gated responses.

Synchronously Amplified Photoacoustic Image Recovery (SAPhIRe) offers improved background suppression using non-linear properties of modulatable contrast agents. Using SAPhIRe, multiple contrast agents in the same absorption window can be detected independently based on their unique triplet-state lifetimes. Here, we have demonstrated the unmixing of rose bengal and eosin Y signals from solution based on triplet-state lifetime mapping using both fluorescence and photoacoustics.

Factors Influencing the Repeated Transient Optical Droplet Vaporization Threshold and Lifetimes of Phase Change, Perfluorocarbon Nanodroplets.

Perfluorocarbon nanodroplets (PFCnDs) are sub-micrometer emulsions composed of a surfactant-encased perfluorocarbon (PFC) liquid and can be formulated to transiently vaporize through optical stimulation. However, the factors governing repeated optical droplet vaporization (ODV) have not been investigated. In this study, we employ high-frame-rate ultrasound (US) to characterize the ODV thresholds of various formulations and imaging parameters and identify those that exhibit low vaporization thresholds and repeatable vaporization.

Improved magnetic delivery of cells to the trabecular meshwork in mice.

Glaucoma is the leading cause of irreversible blindness worldwide and its most prevalent subtype is primary open angle glaucoma (POAG). One pathological change in POAG is loss of cells in the trabecular meshwork (TM), which is thought to contribute to ocular hypertension and has thus motivated development of cell-based therapies to refunctionalize the TM. TM cell therapy has shown promise in intraocular pressure (IOP) control, but existing cell delivery techniques suffer from poor delivery efficiency.

In vivo shear wave elasticity imaging for assessment of diaphragm function in muscular dystrophy.

Duchenne muscular dystrophy (DMD) causes patients to suffer from ambulatory disability and cardiorespiratory failure, the latter of which leads to premature death. Due to its role in respiration, the diaphragm is an important muscle for study. A common method for evaluating diaphragm function is ex vivo force testing, which only allows for an end point measurement.

pH-responsive ratiometric photoacoustic imaging of polyaniline nanoparticle-coated needle for targeted cancer biopsy.

Cancer microenvironment exhibits lower pH compared to healthy tissues, a characteristic which can be exploited using a pH-responsive needle to increase the accuracy of cancer biopsy. A needle, coated with pH-responsive polyaniline (PANI) nanoparticles (PANI-needle), is developed for the minimally invasive and quantitative pH analysis of tissue based on ratiometric photoacoustic (PA) imaging. The ratiometric PA signal from the PANI-needle within the 850-700 nm wavelength range shows a linear response as pH changes from 7.

Real-time monitoring of NIR-triggered drug release from phase-changeable nanodroplets by photoacoustic/ultrasound imaging.

Optical-responsive nanodroplets have recently been studied as a new mode of remotely controlled drug delivery. As a class of new emerging smart drug carriers, NIR-absorber-loaded perfluorocarbon nanodroplets can be converted into gas bubbles through laser stimulation, called optical droplet vaporization (ODV), which provides a potential strategy to deliver therapeutic agents to solid tumors on demand. However, there is a lack of suitable technologies to monitor these drug-loaded nanodroplet behaviors in vivo, and control the site and amount of drug released.

A Scholte wave approach for ultrasonic surface acoustic wave elastography.

Background: Pathological changes in tissues are often related to changes in tissue mechanical properties, making elastography an important tool for medical applications. Among the existing elastography methods, ultrasound elastography is of great interest due to the inherent advantages of ultrasound imaging technology, such as low cost, portability, safety, and wide availability. Although ultrasonic shear wave elastography, as a platform technology, can potentially quantify the elasticity of tissue at any depth, its current implementation cannot assess superficial tissue but can only image deep tissue.

Characterizing a photoacoustic and fluorescence imaging platform for preclinical murine longitudinal studies.

Significance: To effectively study preclinical animal models, medical imaging technology must be developed with a high enough resolution and sensitivity to perform anatomical, functional, and molecular assessments. Photoacoustic (PA) tomography provides high resolution and specificity, and fluorescence (FL) molecular tomography provides high sensitivity; the combination of these imaging modes will enable a wide range of research applications to be studied in small animals.

Aim: We introduce and characterize a dual-modality PA and FL imaging platform using and phantom experiments.

Noninvasive ultrasound assessment of tissue internal pressure using dual mode elasticity imaging: a phantom study.

Tissue internal pressure, such as interstitial fluid pressure in solid tumors and intramuscular pressure in compartment syndrome, is closely related to the pathological state of tissues. It is of great diagnostic value to measure and/or monitor the internal pressure of targeted tissues. Because most of the current methods for measuring tissue pressure are invasive, noninvasive methods are highly desired.

Correction: photoacoustic image-guided tumor photothermal therapy and real-time temperature monitoring using a core-shell polypyrrole@CuS nanohybrid.

Correction for ' photoacoustic image-guided tumor photothermal therapy and real-time temperature monitoring using a core-shell polypyrrole@CuS nanohybrid' by Yang Cao , , 2022, , 12069-12076, https://doi.org/10.1039/D2NR02848D.

High-Frequency Ultrasound Imaging With Sub-Nyquist Sampling.

Implementation of a high-frequency ultrasound (HFUS) beamformer is computationally challenging because of its high sampling rate. This article introduces an efficient beamformer with sub-Nyquist sampling (or bandpass sampling) that is suitable for HFUS imaging. Our approach used channel radio frequency data sampled at bandpass sampling rate (i.

In vivo safety study using radiation at wavelengths and dosages relevant to intravascular imaging.

Significance: Intravascular photoacoustic (IVPA) imaging can identify native lipid in atherosclerotic plaques in vivo. However, the large number of laser pulses required to produce 3D images is a safety concern that has not been fully addressed.

Aim: We aim to evaluate if irradiation at wavelengths and dosages relevant to IVPA imaging causes target vessel damage.

Gold nanoparticles conjugated with DNA aptamer for photoacoustic detection of human matrix metalloproteinase-9.

Matrix metalloproteinase-9 (MMP-9) plays major roles in extracellular matrix (ECM) remodeling and membrane protein cleavage, suggesting a high correlation with cancer cell invasion and tumor metastasis. Here, we present a contrast agent based on a DNA aptamer that can selectively target human MMP-9 in the tumor microenvironment (TME) with high affinity and sensitivity. Surface modification of plasmonic gold nanospheres with the MMP-9 aptamer and its complementary sequences allows the nanospheres to aggregate in the presence of human MMP-9 through DNA displacement and hybridization.

Clinically translatable quantitative molecular photoacoustic imaging with liposome-encapsulated ICG J-aggregates.

Photoacoustic (PA) imaging is a functional and molecular imaging technique capable of high sensitivity and spatiotemporal resolution at depth. Widespread use of PA imaging, however, is limited by currently available contrast agents, which either lack PA-signal-generation ability for deep imaging or their absorbance spectra overlap with hemoglobin, reducing sensitivity. Here we report on a PA contrast agent based on targeted liposomes loaded with J-aggregated indocyanine green (ICG) dye (i.

Formulation and Acoustic Modulation of Optically Vaporized Perfluorocarbon Nanodroplets.

Microbubbles are the most commonly used imaging contrast agent in ultrasound. However, due to their size, they are limited to vascular compartments. These microbubbles can be condensed or formulated as perfluorocarbon nanodroplets (PFCnDs) that are small enough to extravasate and then be triggered acoustically at the target site.