scholarly journals Real-Time 3D Laparoscopic Ultrasonography

2005 ◽  
Vol 27 (3) ◽  
pp. 129-144 ◽  
Author(s):  
Edward D. Light ◽  
Salim F. Idriss ◽  
Kathryn F. Sullivan ◽  
Patrick D. Wolf ◽  
Stephen W. Smith
Keyword(s):  
Real Time ◽  
Insertion Loss ◽  
Pulmonary Veins ◽  
Intracardiac Echocardiography ◽  
Center Frequency ◽  
Ultrasound Transducers ◽  
Laparoscopic Ultrasonography ◽  
Chamber View ◽  
2D Array

We have previously described 2D array ultrasound transducers operating up to 10 MHz for applications including real time 3D transthoracic imaging, real time volumetric intracardiac echocardiography (ICE), real time 3D intravascular ultrasound (IVUS) imaging, and real time 3D transesophageal echocardiography (TEE). We have recently built a pair of 2D array transducers for real time 3D laparoscopic ultrasonography (3D LUS). These transducers are intended to be placed down a trocar during minimally invasive surgery. The first is a forward viewing 5 MHz, 11 times 19 array with 198 operating elements. It was built on an 8 layer multilayer flex circuit. The interelement spacing is 0.20 mm yielding an aperture that is 2.2 mm × 3.8 mm. The O.D. of the completed transducer is 10.2 mm and includes a 2 mm tool port. The average measured center frequency is 4.5 MHz, and the −6 dB bandwidth ranges from 15% to 30%. The 50 Ω insertion loss, including Gore MicroFlat cabling, is −81.2 dB. The second transducer is a 7 MHz, 36 times 36 array with 504 operating elements. It was built upon a 10 layer multilayer flex circuit. This transducer is in the forward viewing configuration and the interelement spacing is 0.18 mm. The total aperture size is 6.48 mm x 6.48 mm. The O.D. of the completed transducer is 11.4 mm. The average measured center frequency is 7.2 MHz, and the −6 dB bandwidth ranges from 18% to 33%. The 50 Ω insertion loss is −79.5 dB, including Gore MicroFlat cable. Real-time in vivo 3D images of canine hearts have been made including an apical 4-chamber view from a substernal access with the first transducer to monitor cardiac function. In addition, we produced real time 3D rendered images of the right pulmonary veins from a right parasternal access with the second transducer, which would be valuable in the guidance of cardiac ablation catheters for treatment of atrial fibrillation.

scholarly journals Metabolite-Specific Echo-Planar Imaging of Hyperpolarized [1-13C]Pyruvate at 4.7 T

Tomography ◽  
2021 ◽  
Vol 7 (3) ◽  
pp. 466-476
Author(s):  
Tyler Blazey ◽  
Galen D Reed ◽  
Joel R Garbow ◽  
Cornelius von Morze
Keyword(s):  
Real Time ◽  
Excitation Pulse ◽  
Flip Angle ◽  
Center Frequency ◽  
Planar Imaging ◽  
Resonance Effects ◽  
Frequency Adjustment ◽  
Spectral Selectivity ◽  
Echo Planar

Although hyperpolarization (HP) greatly increases the sensitivity of 13C MR, the usefulness of HP in vivo is limited by the short lifetime of HP agents. To address this limitation, we developed an echo-planar (EPI) sequence with spectral-spatial radiofrequency (SSRF) pulses for fast and efficient metabolite-specific imaging of HP [1-13C]pyruvate and [1-13C]lactate at 4.7 T. The spatial and spectral selectivity of each SSRF pulse was verified using simulations and phantom testing. EPI and CSI imaging of the rat abdomen were compared in the same rat after injecting HP [1-13C]pyruvate. A procedure was also developed to automatically set the SSRF excitation pulse frequencies based on real-time scanner feedback. The most significant results of this study are the demonstration that a greater spatial and temporal resolution is attainable by metabolite-specific EPI as compared with CSI, and the enhanced lifetime of the HP signal in EPI, which is attributable to the independent flip angle control between metabolites. Real-time center frequency adjustment was also highly effective for minimizing off-resonance effects. To the best of our knowledge, this is the first demonstration of metabolite-specific HP 13C EPI at 4.7 T. In conclusion, metabolite-specific EPI using SSRF pulses is an effective way to image HP [1-13C]pyruvate and [1-13C]lactate at 4.7 T.

Progress in Two-Dimensional Arrays for Real-Time Volumetric Imaging

1998 ◽  
Vol 20 (1) ◽  
pp. 1-15 ◽  
Author(s):  
E. D. Light ◽  
R. E. Davidsen ◽  
J.O. Fiering ◽  
T. A. Hruschka ◽  
S. W. Smith
Keyword(s):  
Real Time ◽  
Insertion Loss ◽  
Imaging System ◽  
Two Dimensional ◽  
Volumetric Imaging ◽  
Dimensional Array ◽  
Transducer Arrays ◽  
Volumetric Images ◽  
Duke University

The design, fabrication, and evaluation of two dimensional array transducers for real-time volumetric imaging are described. The transducers we have previously described operated at frequencies below 3 MHz and were unwieldy to the operator because of the interconnect schemes used in connecting to the transducer handle. Several new transducers have been developed using new connection technology. A 40 × 40 = 1,600 element, 3.5 MHz array was fabricated with 256 transmit and 256 receive elements. A 60 × 60 = 3,600 element 5.0 MHz array was constructed with 248 transmit and 256 receive elements. An 80 × 80 = 6,400 element, 2.5 MHz array was fabricated with 256 transmit and 208 receive elements. 2-D transducer arrays were also developed for volumetric scanning in an intracardiac catheter, a 10 × 10 = 100 element 5.0 MHz forward-looking array and an 11 × 13 = 143 element 5.0 MHz side-scanning array. The −6 dB fractional bandwidths for the different arrays varied from 50% to 63%, and the 50 Ω insertion loss for all the transducers was about −64 dB. The transducers were used to generate real-time volumetric images in phantoms and in vivo using the Duke University real time volumetric imaging system, which is capable of generating multiple planes at any desired angle and depth within the pyramidal volume.

Abstract 5960: Implementation of Noninvasive Subharmonic Pressure Estimation on a Commercial Ultrasound Scanner

Circulation ◽  
2008 ◽  
Vol 118 (suppl_18) ◽  
Author(s):  
Lauren M Leodore ◽  
Corina Leung ◽  
Laurent Pelissier ◽  
Flemming Forsberg
Keyword(s):  
Contrast Agents ◽  
Real Time ◽  
Pressure Range ◽  
Linear Regression Analysis ◽  
Heart Association ◽  
Center Frequency ◽  
Single Element ◽  
Pressure Estimation

This project aims to monitor and quantify intra-cardiac pressures via contrast-enhanced subharmonic imaging. We have proposed subharmonic aided pressure estimation (SHAPE; U.S. Patent 6,302,845) utilizing microbubble-based contrast agent signals for the noninvasive estimation of hydrostatic blood pressures in the heart cavities and in this study implemented real-time SHAPE on a commercial US scanner. An experimental pulse-echo system for SHAPE was constructed based on two single element transducers assembled confocally at a 60° angle to each other. A transducer with a bandwidth of 38% and a center frequency of 2.2 MHz (Staveley, East Hartford, CT) was used as the transmitter and a second transducer with a bandwidth of 86% and a center frequency of 3.6 MHz (Etalon Inc., Lebanon, IN) was the receiver. Changes in first, second, and subharmonic amplitudes of 6 different US contrast agents were measured in vitro at hydrostatic pressures from 0 –186 mmHg, acoustic pressures from 0.35– 0.60 MPa and frequencies of 2.5– 6.6 MHz. The optimal parameters for SHAPE were determined using linear regression analysis and implemented on a Sonix RP scanner (Ultrasonix Medical Corp, Richmond, Canada). The real-time implementation of SHAPE was tested in vitro. Over the pressure range studied the 1st and 2nd harmonic amplitudes reduced ~2 dB for all US contrast agents. Over the same pressure range, the subharmonic amplitudes decreased by 10 –14 dB and excellent linear regressions were achieved with the hydrostatic pressure variations (r 2 >0.98, p < 0.001). The optimal sensitivity for SHAPE was achieved at a transmit frequency of 2.5 MHz (i.e., receiving at 1.25 MHz) at a 0.35 MPa acoustic pressure using Sonazoid (GE Healthcare, Oslo, Norway) which declined ~14.4 dB in vitro. A Sonix RP scanner was modified to implement SHAPE on a phased array transducer PA4 –2 with a frequency range from 1.5– 4.5 MHz. A pulse inversion technique was used and the subharmonic signals are displayed in real-time and can also be stored for off-line analysis. SHAPE offers the possibility of allowing pressure gradients in the heart to be obtained noninvasively. Future studies will include in vivo pressure measurements. Supported by AHA grant no 06554414 and NIH HL081892. This research has received full or partial funding support from the American Heart Association, AHA Great Rivers Affiliate (Delaware, Kentucky, Ohio, Pennsylvania & West Virginia).

A 120-MHz Ultrasound Probe for Tissue Imaging

1996 ◽  
Vol 18 (4) ◽  
pp. 231-239 ◽  
Author(s):  
Koichi Yokosawa ◽  
Ryuichi Shinomura ◽  
Shyuzo Sano ◽  
Yukio Ito ◽  
Shizuo Ishikawa ◽  
...  
Keyword(s):  
High Frequency ◽  
Tissue Characterization ◽  
Lateral Resolution ◽  
Tissue Imaging ◽  
Surrounding Tissue ◽  
Center Frequency ◽  
Ultrasound Transducers ◽  
High Frequency Region

Ultrasound transducers with center frequency above 100 MHz are expected to be used for future diagnostic tissue characterization because of their high lateral resolution. We have fabricated a 120-MHz transducer that consists of a ZnO piezoelectric film on a sapphire substrate that has a concave acoustic lens. The lateral resolution was calculated as 13 μm. The insertion loss of the transducer, defined as the difference between the received voltage and the transmitted one, was −45 dB. The 6-dB bandwidth of the received signal was approximately 40 MHz. The transducer was mounted in a rod-shaped probe to ensure contact with in vivo tissue, because of the low penetration of ultrasound in the high frequency region. While the probe is rotated and moved along its axis mechanically, the transducer receives backscattered ultrasound from the surrounding tissue on a cylindrical plane that is kept a constant distance from the probe surface. The feasibility of this high-frequency tissue imaging probe has been demonstrated by obtaining preliminary images of an in vitro bovine kidney.

scholarly journals Signed Real-Time Delay Multiply and Sum Beamforming for Multispectral Photoacoustic Imaging

2018 ◽  
Vol 4 (10) ◽  
pp. 121 ◽  
Author(s):  
Thomas Kirchner ◽  
Franz Sattler ◽  
Janek Gröhl ◽  
Lena Maier-Hein
Keyword(s):  
Open Source ◽  
Real Time ◽  
Photoacoustic Imaging ◽  
Signal To Noise Ratio ◽  
Ultrasound Transducers ◽  
Full Spectrum ◽  
Simple Implementation

Reconstruction of photoacoustic (PA) images acquired with clinical ultrasound transducers is usually performed using the Delay and Sum (DAS) beamforming algorithm. Recently, a variant of DAS, referred to as Delay Multiply and Sum (DMAS) beamforming has been shown to provide increased contrast, signal-to-noise ratio (SNR) and resolution in PA imaging. The main reasons for the use of DAS beamforming in photoacoustics are its simple implementation, real-time capability, and the linearity of the beamformed image to the PA signal. This is crucial for the identification of different chromophores in multispectral PA applications. In contrast, current DMAS implementations are not responsive to the full spectrum of sound frequencies from a photoacoustic source and have not been shown to provide a reconstruction linear to the PA signal. Furthermore, due to its increased computational complexity, DMAS has not been shown yet to work in real-time. Here, we present an open-source real-time variant of the DMAS algorithm, signed DMAS (sDMAS), that ensures linearity in the original PA signal response while providing the increased image quality of DMAS. We show the applicability of sDMAS for multispectral PA applications, in vitro and in vivo. The sDMAS and reference DAS algorithms were integrated in the open-source Medical Imaging Interaction Toolkit (MITK) and are available as real-time capable implementations.

Voltammetric Detection of Tetrodotoxin Real-Time In Vivo of Mouse Organs using DNA-Immobilized Carbon Nanotube Sensors

2019 ◽  
Vol 15 (5) ◽  
pp. 567-574
Author(s):  
Huck Jun Hong ◽  
Suw Young Ly
Keyword(s):  
Carbon Nanotube ◽  
Real Time ◽  
Anticancer Agents ◽  
Cancer Metastasis ◽  
Anodic Stripping Voltammetry ◽  
Stripping Voltammetry ◽  
Takifugu Rubripes ◽  
In Vivo Detection ◽  
Voltammetric Detection

Background: Tetrodotoxin (TTX) is a biosynthesized neurotoxin that exhibits powerful anticancer and analgesic abilities by inhibiting voltage-gated sodium channels that are crucial for cancer metastasis and pain delivery. However, for the toxin’s future medical applications to come true, accurate, inexpensive, and real-time in vivo detection of TTX remains as a fundamental step. Methods: In this study, highly purified TTX extracted from organs of Takifugu rubripes was injected and detected in vivo of mouse organs (liver, heart, and intestines) using Cyclic Voltammetry (CV) and Square Wave Anodic Stripping Voltammetry (SWASV) for the first time. In vivo detection of TTX was performed with auxiliary, reference, and working herring sperm DNA-immobilized carbon nanotube sensor systems. Results: DNA-immobilization and optimization of amplitude (V), stripping time (sec), increment (mV), and frequency (Hz) parameters for utilized sensors amplified detected peak currents, while highly sensitive in vivo detection limits, 3.43 µg L-1 for CV and 1.21 µg L-1 for SWASV, were attained. Developed sensors herein were confirmed to be more sensitive and selective than conventional graphite rodelectrodes modified likewise. A linear relationship was observed between injected TTX concentration and anodic spike peak height. Microscopic examination displayed coagulation and abnormalities in mouse organs, confirming the powerful neurotoxicity of extracted TTX. Conclusion: These results established the diagnostic measures for TTX detection regarding in vivo application of neurotoxin-deviated anticancer agents and analgesics, as well as TTX from food poisoning and environmental contamination.

scholarly journals Real-time observation of tetrapyrrole binding to an engineered bacterial phytochrome

2021 ◽  
Vol 4 (1) ◽  
Author(s):  
Yusaku Hontani ◽  
Mikhail Baloban ◽  
Francisco Velazquez Escobar ◽  
Swetta A. Jansen ◽  
Daria M. Shcherbakova ◽  
...  
Keyword(s):  
Real Time ◽  
Rational Design ◽  
Near Infrared ◽  
Fluorescent Proteins ◽  
Covalent Bond ◽  
Binding Pocket ◽  
Tissue Imaging ◽  
Covalent Attachment ◽  
Time Resolved

AbstractNear-infrared fluorescent proteins (NIR FPs) engineered from bacterial phytochromes are widely used for structural and functional deep-tissue imaging in vivo. To fluoresce, NIR FPs covalently bind a chromophore, such as biliverdin IXa tetrapyrrole. The efficiency of biliverdin binding directly affects the fluorescence properties, rendering understanding of its molecular mechanism of major importance. miRFP proteins constitute a family of bright monomeric NIR FPs that comprise a Per-ARNT-Sim (PAS) and cGMP-specific phosphodiesterases - Adenylyl cyclases - FhlA (GAF) domain. Here, we structurally analyze biliverdin binding to miRFPs in real time using time-resolved stimulated Raman spectroscopy and quantum mechanics/molecular mechanics (QM/MM) calculations. Biliverdin undergoes isomerization, localization to its binding pocket, and pyrrolenine nitrogen protonation in <1 min, followed by hydrogen bond rearrangement in ~2 min. The covalent attachment to a cysteine in the GAF domain was detected in 4.3 min and 19 min in miRFP670 and its C20A mutant, respectively. In miRFP670, a second C–S covalent bond formation to a cysteine in the PAS domain occurred in 14 min, providing a rigid tetrapyrrole structure with high brightness. Our findings provide insights for the rational design of NIR FPs and a novel method to assess cofactor binding to light-sensitive proteins.

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