Dataset Information

Unambiguous Identification and Visualization of an Acoustically Active Catheter by Ultrasound Imaging in Real Time: Theory, Algorithm, and Phantom Experiments.

ABSTRACT: OBJECTIVE:Ultrasound-guided biopsies and minimally invasive procedures have been used in numerous medical applications, including catheter guidance. The biggest challenge for catheter guidance by ultrasound lies in distinguishing the catheter from neighboring tissue, as well as the ability to differentiate the catheter body from its tip. METHODS:In our previous work, we introduced a functional prototype of an acoustically active catheter, in which a miniature piezoelectric crystal allowed accurate localization of the catheter tip by pulsed wave (PW) Doppler imaging and Doppler spectrogram. In this paper, the theory behind the symmetric Doppler shift due to the interaction of ultrasound wave with a vibrating piezoelectric crystal is explained. The theory is validated in an experimental continuous flow phantom setup. A novel algorithm, symmetric frequency detection algorithm, is presented for identification and visualization of the catheter tip in real time along with B-mode and PW Doppler. RESULTS:The catheter tip is identified with a distinct color differentiable from common Doppler colors with a frame rate varying from 22 to 50 Hz. The catheter tip can be visualized in a small region of 2.4 mm in the elevational direction. CONCLUSION:The algorithm can be implemented in most clinical ultrasound machines with minor additions to the PW Doppler processing algorithm. The algorithm is optimized to be robust for a variety of blood flow velocities and is shown to perform well when the signal from the blood is on par in amplitude with the catheter signal. SIGNIFICANCE:Unambiguous and distinct visualization of catheter tip facilitates real-time tracking of the catheter and aids minimally invasive procedures.

SUBMITTER: Kumar V

PROVIDER: S-EPMC5999572 | biostudies-literature | 2018 Jul

REPOSITORIES: biostudies-literature

ACCESS DATA

Publications

Unambiguous Identification and Visualization of an Acoustically Active Catheter by Ultrasound Imaging in Real Time: Theory, Algorithm, and Phantom Experiments.

Kumar Viksit V Liu Richard R Kinnick Randall R RR Gregory Adriana A Alizad Azra A Belohlavek Marek M Fatemi Mostafa M

IEEE transactions on bio-medical engineering 20170925 7

<h4>Objective</h4>Ultrasound-guided biopsies and minimally invasive procedures have been used in numerous medical applications, including catheter guidance. The biggest challenge for catheter guidance by ultrasound lies in distinguishing the catheter from neighboring tissue, as well as the ability to differentiate the catheter body from its tip.<h4>Methods</h4>In our previous work, we introduced a functional prototype of an acoustically active catheter, in which a miniature piezoelectric crystal ...[more]

PMID: 28952929

Similar Datasets

Project description:BackgroundThere is growing interest in limb contrast-enhanced ultrasound (CEU) perfusion imaging for the evaluation of peripheral artery disease. Because of low resting microvascular blood flow in skeletal muscle, signal enhancement during limb CEU is prohibitively low for real-time imaging. The aim of this study was to test the hypothesis that this obstacle can be overcome by intermediate- rather than low-power CEU when performed with an acoustically resilient microbubble agent.MethodsViscoelastic properties of Definity and Sonazoid were assessed by measuring bulk modulus during incremental increases in ambient pressure to 200 mm Hg. Comparison of in vivo microbubble destruction and signal enhancement at a mechanical index (MI) of 0.1 to 0.4 was performed by sequential reduction in pulsing interval from 10 to 0.05 sec during limb CEU at 7 MHz in mice and 1.8 MHz in dogs. Destruction was also assessed by broadband signal generation during passive cavitation detection. Real-time CEU perfusion imaging with destruction-replenishment was then performed at 1.8 MHz in dogs using an MI of 0.1, 0.2, or 0.3.ResultsSonazoid had a higher bulk modulus than Definity (66 ± 12 vs 29 ± 2 kPa, P = .02) and exhibited less inertial cavitation (destruction) at MIs ≥ 0.2. On in vivo CEU, maximal signal intensity increased incrementally with MI for both agents and was equivalent between agents except at an MI of 0.1 (60% and 85% lower for Sonazoid at 7 and 1.8 MHz, respectively, P < .05). However, on progressive shortening of the pulsing interval, Definity was nearly completely destroyed at MIs ≥ 0.2 at 1.8 and 7 MHz, whereas Sonazoid was destroyed only at 1.8 MHz at MIs ≥ 0.3. As a result, real-time CEU perfusion imaging demonstrated approximately fourfold greater enhancement for Sonazoid at an MI of 0.3 to 0.4.ConclusionsRobust signal enhancement during real-time CEU perfusion imaging of the limb is possible when using intermediate-power imaging coupled with a durable microbubble contrast agent.

Project description:Ultrasound-induced mild hyperthermia has advantages for noninvasive, localized and controlled drug delivery. In this study, a tissue-mimicking agarose-based phantom with a thermally sensitive indicator was developed for studying the spatial drug delivery profile using ultrasound-induced mild hyperthermia.Agarose powder, regular evaporated milk, Dulbecco's phosphate-buffered saline (DPBS), n-propanol, and silicon carbide powder were homogeneously mixed with low temperature sensitive liposomes (LTSLs) loaded with a self-quenched near-infrared (NIR) fluorescent dye. A dual-mode linear array ultrasound transducer was used for insonation at 1.54 MHz with a total acoustic power and acoustic pressure of 2.0 W and 1.5 MPa, respectively. After insonation, the dye release pattern in the phantom was quantified based on optical images, and the three-dimensional release profile was reconstructed and analyzed. A finite-difference time-domain-based algorithm was developed to simulate both the temperature distribution and spatial dye diffusion as a function of time. Finally, the simulated dye diffusion patterns were compared to experimental measurements.Self-quenching of the fluorescent dye in DPBS was substantial at a concentration of 6.25×10(-2) mM or greater. The transition temperature of LTSLs in the phantom was 35 °C, and the release reached 90% at 37 °C. The simulated temperature for hyperthermia correlated with the thermocouple measurements with a mean error between 0.03±0.01 and 0.06±0.02 °C. The R2 value between the experimental and simulated spatial extent of the dye diffusion, defined by the half-peak level in the elevation, lateral and depth directions, was 0.99 (slope=1.08), 0.95 (slope=0.99), and 0.80 (slope=1.04), respectively, indicating the experimental and simulated dye release profiles were similar.The combination of LTSLs encapsulating a fluorescent dye and an optically transparent phantom is useful for visualizing and modeling drug release in vitro following ultrasound-induced mild hyperthermia. The coupled temperature simulation and dye-diffusion simulation tools were validated with the experimental system and can be used to optimize the thermal dose and spatial and temporal dye release pattern.

Project description:A novel cardiac motion correction algorithm has been introduced recently. Unlike other segmentation-based approaches it is fully automatic and capable of correcting motion artifacts of myocardial wall and other moving structures as well as coronary arteries of the heart. In addition, it requires raw data of only less than a single rotation for motion estimation and correction, which is a significant advantage from the perspective of x-ray exposure and workflow. The aim of this study is to explore the capability of the proposed method through phantoms and in-vivo experiments. Motion correction of coronary arteries and other heart structures including myocardial wall is the main focus of the evaluation. First, we provide a brief introduction to the concept of the motion correction algorithm. Next we address the procedure of our studies using an XCAT phantom and commercially available physical phantoms. Results of XCAT phantom demonstrate that our solution significantly improves the structural similarity of coronary arteries compared to FBP (proposed: 0.94, FBP: 0.77, p<0.001). Besides, it provides significantly lower root mean square error (proposed: 20.27, FBP: 25.33, p = 0.01) of the whole heart image. Mocomo phantom study shows that the proposed method improves the visualization of coronary arteries estimated based on motion score (1: worst, 5: best) from two experienced radiologists (proposed: 3.5, FBP: 2.1, p<0.001). The results of these phantom studies reveal that the proposed has a great potential in handling motion artifacts of other heart structures as well as coronary arteries. Finally, we provide the results of in-vivo animal and human studies. The 3D and 4D heart images show a consistently superior performance in the visualization of coronary arteries along with myocardial wall and other cardiothoracic structures. Based on these findings of our studies, we are of the opinion that our solution has a considerable potential to improve temporal resolution of cardiac CT imaging. This would open the door to innovations in structural or functional diagnosis of the heart.

Dataset Information

Unambiguous Identification and Visualization of an Acoustically Active Catheter by Ultrasound Imaging in Real Time: Theory, Algorithm, and Phantom Experiments.

Publications

Unambiguous Identification and Visualization of an Acoustically Active Catheter by Ultrasound Imaging in Real Time: Theory, Algorithm, and Phantom Experiments.

Similar Datasets

OmicsDI is part of the ELIXIR infrastructure

Tweets