IEEE transactions on ultrasonics, ferroelectrics, and frequency control
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IEEE Trans Ultrason Ferroelectr Freq Control · Apr 2008
Three-dimensional motion measurements using feature tracking.
Feature tracking was developed to efficiently compute motion measurements from volumetric ultrasound images. Prior studies have demonstrated the motion magnitude accuracy and computation speed of feature tracking. However, the previous feature tracking implementations were limited by performance of their calculations in rectilinear coordinates. ⋯ This study presents an improved feature tracking method which achieves further computation speed gains by performing all calculations in the native spherical coordinates of the 3-D ultrasound image. The novel method utilizes a statistical analysis of tracked directions of motion to achieve better rejection of false tracking matches. Results from in vitro tracking of a speckle target show that the new feature tracking method is significantly faster than correlation search and can accurately determine target motion magnitude and 3-D direction.
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IEEE Trans Ultrason Ferroelectr Freq Control · Jan 2008
Vibrating interventional device detection using real-time 3-D color Doppler.
Ultrasound image guidance of interventional devices during minimally invasive surgery provides the clinician with improved soft tissue contrast while reducing ionizing radiation exposure. One problem with ultrasound image guidance is poor visualization of the device tip during the clinical procedure. We have described previously guidance of several interventional devices using a real-time 3-D (RT3-D) ultrasound system with 3-D color Doppler combined with the ColorMark technology. ⋯ Improved RF and wall filters increased the detected color Doppler sensitivity by 14 dB. In three simultaneous planes from the in vivo 3-D scan, we identified both the septal puncture needle and the biopsy forceps within the right atrium using the 2.5 MHz probe. A new display filter was used to suppress the unwanted flash artifact associated with physiological motion.
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IEEE Trans Ultrason Ferroelectr Freq Control · Sep 2007
LetterInducing and imaging thermal strain using a single ultrasound linear array.
For the first time, the feasibility of inducing and imaging thermal strain using an ultrasound imaging array is demonstrated. A commercial ultrasound scanner was used to heat and image a gelatin phantom with a cylindrical rubber inclusion. The inclusion was successfully characterized as an oil-bearing material using thermal strain imaging.
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IEEE Trans Ultrason Ferroelectr Freq Control · Apr 2007
High-frequency surface acoustic waves excited on thin-oriented LiNbO3 single-crystal layers transferred onto silicon.
The need for high-frequency, wide-band filters has instigated many developments based on combining thin piezoelectric films and high acoustic velocity materials (sapphire, diamond-like carbon, silicon, etc.) to ease the manufacture of devices operating above 2 GHz. In the present work, a technological process has been developed to achieve thin-oriented, single-crystal lithium niobate (LiNbO3) layers deposited on (100) silicon wafers for the fabrication of radio-frequency (RF) surface acoustic wave (SAW) devices. ⋯ Technological aspects then are described briefly. Experimental results are presented and compared to the state of art.
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IEEE Trans Ultrason Ferroelectr Freq Control · Feb 2007
Finite element analysis of tissue deformation with a radiofrequency ablation electrode for strain imaging.
Recent studies have shown that radiofrequency (RF) electrode displacement or deformation-based strain imaging can be used as an alternate imaging modality to monitor and to evaluate ablative therapies for liver tumors. This paper describes a biomechanical model used to study RF electrode deformation-based strain imaging, in conjunction with a simulated medical ultrasound linear array transducer. The computer simulations reported here are important steps toward understanding this biomechanical system in vivo, thus providing a basis for improving system design, including the motion tracking algorithm and image guidance for performing RF electrode displacement-strain imaging in vivo.