다중혈관 관상동맥 환자에서 y-문합을 이용하여 양쪽 내흉동맥만을 사용한 우회술의 조기 성적

Photoacoustic tomography (PAT) can create multiscale multicontrast images of living biological structures ranging from organelles to organs. This emerging technology overcomes the high degree of scattering of optical photons in biological tissue by making use of the photoacoustic effect. Light absorption by molecules creates a thermally induced pressure jump that launches ultrasonic waves, which are received by acoustic detectors to form images. Different implementations of PAT allow the spatial resolution to be scaled with the desired imaging depth in tissue while a high depth-to-resolution ratio is maintained. As a rule of thumb, the achievable spatial resolution is on the order of 1/200 of the desired imaging depth, which can reach up to 7 centimeters. PAT provides anatomical, functional, metabolic, molecular, and genetic contrasts of vasculature, hemodynamics, oxygen metabolism, biomarkers, and gene expression. We review the state of the art of PAT for both biological and clinical studies and discuss future prospects.

Photoacoustic Tomography: In Vivo Imaging from Organelles to Organs

Hydrogels in pharmaceutical formulations.

비만아 부모의 돌봄 경험: q 방법론

Additive manufacturing (AM) alias 3D printing translates computer-aided design (CAD) virtual 3D models into physical objects. By digital slicing of CAD, 3D scan, or tomography data, AM builds objects layer by layer without the need for molds or machining. AM enables decentralized fabrication of customized objects on demand by exploiting digital information storage and retrieval via the Internet. The ongoing transition from rapid prototyping to rapid manufacturing prompts new challenges for mechanical engineers and materials scientists alike. Because polymers are by far the most utilized class of materials for AM, this Review focuses on polymer processing and the development of polymers and advanced polymer systems specifically for AM. AM techniques covered include vat photopolymerization (stereolithography), powder bed fusion (SLS), material and binder jetting (inkjet and aerosol 3D printing), sheet lamination (LOM), extrusion (FDM, 3D dispensing, 3D fiber deposition, and 3D plotting), and 3D bioprinting....

Polymers for 3D Printing and Customized Additive Manufacturing

INTRODUCTION History Role of Ultrasound in Medical Imaging Purpose of the Book Reference Further Reading FUNDAMENTALS OF ACOUSTIC PROPAGATION Stress and Strain Relationships Acoustic Wave Equation Characteristic Impedance Intensity Radiation Force Reflection and Refraction Attenuation, Absorption, and Scattering Nonlinearity Parameter B/A Doppler Effect References ULTRASONIC TRANSDUCERS AND ARRAYS Piezoelectric Effect Piezoelectric Constitutive Equation Ultrasonic Transducers Mechanical Matching Electrical Matching Transducer Beam Characteristics Arrays References GRAY-SCALE ULTRASONIC IMAGING A (Amplitude)-Mode and B (Brightness)-Mode Imaging M-Mode and C-Mode Ultrasound Computed Tomography (CT) Coded Excitation Imaging Compound Imaging Synthetic Aperture Imaging References DOPPLER FLOW MEASUREMENTS Nondirectional CW Flow Meters Directional Doppler Flow Meters Pulsed Doppler Flow Meters Clinical Applications and Doppler Indices Potential Problems in Doppler Measurements Tissue Doppler and Multigate Doppler References FLOW AND DISPLACEMENT IMAGING Color Doppler Flow Imaging Color Doppler Power Imaging Time-Domain Flow Estimation Elasticity Imaging B-Flow Imaging References CONTRAST MEDIA AND HARMONIC IMAGING Contrast Agents Nonlinear Interactions Between Ultrasound and Bubbles Modified Rayleigh-Plesset Equation for Encapsulated Gas Bubbles Solutions to Rayleigh-Plesset Equation Harmonic Imaging Native Tissue Harmonic Imaging Clinical Applications of Contrast Agents and Harmonic Imaging References INTRACAVITY AND HIGH-FREQUENCY (HF) IMAGING Imaging Intravascular Imaging High-Frequency Imaging Acoustic Microscopes References MULTIDIMENSIONAL IMAGING Parallel Processing Multidimensional Arrays Three-Dimensional Imaging References BIOLOGICAL EFFECTS OF ULTRASOUND Acoustic Phenomena at High-Intensity Levels Ultrasound Bioeffects Mechanical Effects and Index References METHODS FOR MEASURING SPEED, ATTENUATION, ABSORPTION, AND SCATTERING Velocity Attenuation Scattering References INDEX

Diagnostic Ultrasound: Imaging and Blood Flow Measurements

At present, clinicians routinely apply ultrasound endoscopy in a variety of interventional procedures that provide treatment solutions for diseased organs. Ultrasound endoscopy not only produces high-resolution images, but also is safe for clinical use and broadly applicable. However, for soft tissue imaging, its mechanical wave-based image contrast fundamentally limits its ability to provide physiologically specific functional information. By contrast, photoacoustic endoscopy possesses a unique combination of functional optical contrast and high spatial resolution at clinically relevant depths, ideal for imaging soft tissues. With these attributes, photoacoustic endoscopy can overcome the current limitations of ultrasound endoscopy. Moreover, the benefits of photoacoustic imaging do not come at the expense of existing ultrasound functions; photoacoustic endoscopy systems are inherently compatible with ultrasound imaging, thereby enabling multimodality imaging with complementary contrast. Here we present simultaneous photoacoustic and ultrasonic dual-mode endoscopy and show its ability to image internal organs in vivo, thus illustrating its potential clinical application.

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Simultaneous functional photoacoustic and ultrasonic endoscopy of internal organs in vivo

This paper discusses the design, fabrication, and testing of sensitive broadband lithium niobate (LiNbO/sub 3/) single-element ultrasonic transducers in the 20-80 MHz frequency range. Transducers of varying dimensions were built for an f# range of 2.0-3.1. The desired focal depths were achieved by either casting an acoustic lens on the transducer face or press-focusing the piezoelectric into a spherical curvature. For designs that required electrical impedance matching, a low impedance transmission line coaxial cable was used. All transducers were tested in a pulse-echo arrangement, whereby the center frequency, bandwidth, insertion loss, and focal depth were measured. Several transducers were fabricated with center frequencies in the 20-80 MHz range with the measured -6 dB bandwidths and two-way insertion loss values ranging from 57 to 74% and 9.6 to 21.3 dB, respectively. Both transducer focusing techniques proved successful in producing highly sensitive, high-frequency, single-element, ultrasonic-imaging transducers. In vivo and in vitro ultrasonic backscatter microscope (UBM) images of human eyes were obtained with the 50 MHz transducers. The high sensitivity of these devices could possibly allow for an increase in depth of penetration, higher image signal-to-noise ratio (SNR), and improved image contrast at high frequencies when compared to previously reported results.

Design of efficient, broadband single-element (20-80 MHz) ultrasonic transducers for medical imaging applications

The ultrasonic volumetric scattering cross section of the erythrocyte has been measured over a range of frequencies by comparing the rms value of the gated backscattered signal from the blood with that of a wave reflected from a flat reflector with known reflection coefficient. It is found to be proportional to the fourth power of the frequency predicted by the wave scattering theory for small particles in the frequency range from 5 MHz to 15 MHz. The relation between the scattering coefficient and the hematocrit is also examined up to a hematocrit of 45 percent. This coefficient is found to increase along with the hematocrit until it reaches a maximum around hematocrit = 26 percent and then decreases as the hematocrit increases. Twersky's wave scattering theory is applied to describe this result.

Scattering of Ultrasound by Blood

Introduction (K. Kirk Shung). Clinical Relevance of Scattering (Gary Thieme). Biological Tissues as Ultrasonic Scattering Media (K.K. Shung and G. Thieme). Acoustic Scattering Theory Applied to Soft Biological Tissues (M.F. Insana and D.G. Brown). Theoretical Models of Ultrasonic Scattering in Blood (L.Y.L. Mo and R.S.C. Cobbold). Standard Substitution Methods for Measuring Ultrasonic Scattering in Tissues (J.M. Reid). Method of Determination of Acoustic Backscatter and Attenuation Coefficients Independent of Depth and Instrumentation (E.L. Madsen). Measurement System Effects in Ultrasonic Scattering Experiments (R.C. Waag and J.P. Astheimer). In Vitro Experimental Results on Ultrasonic Scattering in Biological Tissues (K.K. Shung). Cardiovascular Tissue Characterization In Vivo (S.A. Wickline, J.E. Perez, and J.G. Miller). In Vivo Liver and Splenic Tissue Characterization by Scattering (Brian Garra). In Vivo Ophthalmological Tissue Characterization by Scattering (F.L. Lizzi and E.J. Fellepa). Fetal Lung Tissue Characterization by Scattering (G.A. Thieme, P.L. Carson, C.R. Meyer, and R. Bowerman). Backscatter Imaging (J. Zagzebski, L.X. Yao, E.J. Boote, and Z.F. Lu). Index.

K. Kirk Shung

Papers

Diagnostic Ultrasound: Imaging and Blood Flow Measurements

Simultaneous functional photoacoustic and ultrasonic endoscopy of internal organs in vivo

Design of efficient, broadband single-element (20-80 MHz) ultrasonic transducers for medical imaging applications

Scattering of Ultrasound by Blood

Ultrasonic Scattering in Biological Tissues