Catheter for intravascular ultrasound and photoacoustic imaging

A design and a fabrication method for an intravascular imaging and therapeutic catheters for combined ultrasound, photoacoustic, and elasticity imaging and for optical and/or acoustic therapy of hollow organs and diseased blood vessels and tissues are disclosed in the present invention. The invention comprises both a device—optical fiber-based intravascular catheter designs for combined IVUS/IVPA, and elasticity imaging and for acoustic and/or optical therapy—and a method of combined ultrasound, photoacoustic, and elasticity imaging and optical and/or acoustic therapy. The designs of the catheters are based on single-element catheter-based ultrasound transducers or on ultrasound array-based units coupled with optical fiber, fiber bundles or a combination thereof with specially designed light delivery systems. One approach uses the side fire fiber, similar to the one utilized for biomedical optical spectroscopy. The second catheter design uses the micro-optics in the manner of a probe for optical coherent tomography.Board of Regents, University of Texas Syste

Blinking Phase-Change Nanocapsules Enable Background-Free Ultrasound Imaging

Microbubbles are widely used as contrast agents to improve the diagnostic capability of conventional, highly speckled, low-contrast ultrasound imaging. However, while microbubbles can be used for molecular imaging, these agents are limited to the vascular space due to their large size (\u3e 1 μm). Smaller microbubbles are desired but their ultrasound visualization is limited due to lower echogenicity or higher resonant frequencies. Here we present nanometer scale, phase changing, blinking nanocapsules (BLInCs), which can be repeatedly optically triggered to provide transient contrast and enable background-free ultrasound imaging. In response to irradiation by near-infrared laser pulses, the BLInCs undergo cycles of rapid vaporization followed by recondensation into their native liquid state at body temperature. High frame rate ultrasound imaging measures the dynamic echogenicity changes associated with these controllable, periodic phase transitions. Using a newly developed image processing algorithm, the blinking particles are distinguished from tissue, providing a background-free image of the BLInCs while the underlying B-mode ultrasound image is used as an anatomical reference of the tissue. We demonstrate the function of BLInCs and the associated imaging technique in a tissue-mimicking phantom and in vivo for the identification of the sentinel lymph node. Our studies indicate that BLInCs may become a powerful tool to identify biological targets using a conventional ultrasound imaging system

Imágenes fotoacústicas para diagnósticos médicos

This paper presents some of the highlights about research and development of sub-aquatic acoustics, as well as it gives recognition to the members of the Acoustical Society of America (ASA), who contributed with their work along the Second World War. The results of such work have turned into scientific and engineering achievements, which are published in literature about acoustics.Este artículo presentan algunos de los aspectos más sobresalientes de la investigación y desarrollo de la acústica subacuática, así como reconoce el mérito de miembros de la Sociedad Americana de Acústica (Acoustics Society of America, ASA), quienes contribuyeron con su trabajo durante el período de la Segunda Guerra Mundial. Los resultados de tal trabajo se convirtieron en logros científicos y de ingeniería que aparecen en literatura sobre acústica

Clinical Application of Sonographic Elasticity Imaging for Aging of Deep Venous Thrombosis

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/135197/1/jum2003225443.pd

Combined ultrasound and photoacoustic imaging of metal objects

Methods of combined ultrasound and photoacoustic imaging are provided. In some embodiments, the methods may be used to determine the location or positioning of a metal object in a sample. In other embodiments, the methods may be used to determine the composition of a sample surrounding a metal object. Other methods are also provided.Board of Regents, University of Texas Syste

Three-dimensional static displacement, stimulated echo NMR elasticity imaging

This article presents a method for measuring three-dimensional mechanical displacement and strain fields using stimulated echo MRI. Additional gradient pulses encode internal displacements in response to an externally applied deformation. By limiting the mechanical transition to the stimulated echo mixing time, a more accurate static displacement measurement is obtained. A three-dimensional elasticity reconstruction within a region of interest having a uniform shear modulus along its boundary is performed by numerically solving discretized elasticity equilibrium equations. Data acquisition, strain measurements and reconstruction were performed using a silicone gel phantom containing an inclusion of known elastic properties. A comparison between two-dimensional and three-dimensional reconstructions from simulated and experimental displacement data shows higher accuracy from the three-dimensional reconstruction. The long-term objective of this work is to provide a method for remotely palpating and elastically quantitating manually inaccessible tissues.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/48966/2/m00616.pd

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. The chain geometry results in enhanced photoacoustic signal generation originating from outstanding photothermal characteristics compared to traditional gold contrast agents, such as gold nanorods. Furthermore, the GSCs produce consistent photoacoustic signals at laser fluences within the limits set by the American National Standards Institute. The exceptional photoacoustic response of GSCs allows for high-contrast photoacoustic imaging over multiple imaging sessions. Finally, we demonstrate the utility of our GSCs for molecular photoacoustic cancer imaging, both in vitro and in vivo, through the integration of a tumor-targeting moiety

Feasibility of applying ultrasound strain imaging to detect renal transplant chronic allograft nephropathy

Feasibility of applying ultrasound strain imaging to detect renal transplant chronic allograft nephropathy.Chronic renal transplant fibrosis, often termed Chronic Allograft Nephropathy, may progress undetected. Since renal fibrosis may be accompanied by a change in measurable elastic tissue properties, ultrasound strain measurements may be useful in its detection. Ultrasound strain imaging was performed for two subjects with renal transplants; one with normal renal function and one with mild renal insufficiency and biopsy demonstrated fibrosis. Subjects underwent ultrasound examination with application of a controlled deformation using phase-sensitive, two-dimensional speckle tracking to evaluate internal tissue motion to measure tissue displacement and strain. Measurements over multiple beams for an equivalent deformational stress showed there was a threefold differences in renal cortical strain between the two subjects. These data suggest that ultrasound elasticity imaging may prove useful in measuring mechanical changes related to fibrosis within the transplant kidney

Model-Based Reconstructive Elasticity Imaging Using Ultrasound

Elasticity imaging is a reconstructive imaging technique where tissue motion in response to mechanical excitation is measured using modern imaging systems, and the estimated displacements are then used to reconstruct the spatial distribution of Young's modulus. Here we present an ultrasound elasticity imaging method that utilizes the model-based technique for Young's modulus reconstruction. Based on the geometry of the imaged object, only one axial component of the strain tensor is used. The numerical implementation of the method is highly efficient because the reconstruction is based on an analytic solution of the forward elastic problem. The model-based approach is illustrated using two potential clinical applications: differentiation of liver hemangioma and staging of deep venous thrombosis. Overall, these studies demonstrate that model-based reconstructive elasticity imaging can be used in applications where the geometry of the object and the surrounding tissue is somewhat known and certain assumptions about the pathology can be made