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https://www.readbyqxmd.com/read/29661482/anisotropy-and-spatial-heterogeneity-in-quantitative-ultrasound-parameters-relevance-to-the-study-of-the-human-cervix
#1
Quinton W Guerrero, Helen Feltovich, Ivan M Rosado-Mendez, Lindsey C Carlson, Geng Li, Timothy J Hall
Imaging biomarkers based on quantitative ultrasound can offer valuable information about properties that inform tissue function and behavior such as microstructural organization (e.g., collagen alignment) and viscoelasticity (i.e., compliance). For example, the cervix feels softer as its microstructure remodels during pregnancy, an increase in compliance that can be objectively quantified with shear wave speed and therefore shear wave speed estimation is a potential biomarker of cervical remodeling. Other proposed biomarkers include parameters derived from the backscattered echo signal, such as attenuation and backscattered power loss, because such parameters can provide insight into tissue microstructural alignment and organization...
April 13, 2018: Ultrasound in Medicine & Biology
https://www.readbyqxmd.com/read/29658889/cross-correlation-analysis-of-pulse-wave-propagation-in-arteries-i-in-vitro-i-validation-and-i-in-vivo-i-feasibility
#2
Pierre Nauleau, Iason Zacharias Apostolakis, Matthew McGarry, Elisa E Konofagou
The stiffness of the arteries is known to be an indicator of the progression of various cardiovascular diseases. Clinically, the pulse wave velocity (PWV) is used as a surrogate for the arterial stiffness. Pulse Wave Imaging (PWI) is a non-invasive, ultrasound-based imaging technique capable of mapping the motion of the vessel walls allowing local assessment of the arterial properties. Conventionally, a distinctive feature of the displacement wave (e.g. the 50% upstroke) is tracked across the map to estimate the PWV...
April 16, 2018: Physics in Medicine and Biology
https://www.readbyqxmd.com/read/29651451/toward-dynamic-lumbar-puncture-guidance-using-needle-based-single-element-ultrasound-imaging
#3
Haichong K Zhang, Younsu Kim, Melissa Lin, Mateo Paredes, Karun Kannan, Abhay Moghekar, Nicholas J Durr, Emad M Boctor
Lumbar punctures (LPs) are interventional procedures that are used to collect cerebrospinal fluid. Since the target window is small, physicians have limited success conducting the procedure. The procedure is especially difficult for obese patients due to the increased distance between bone and skin surface. We propose a simple and direct needle insertion platform, enabling image formation by sweeping a needle with a single ultrasound element at the tip. The needle-shaped ultrasound transducer can not only sense the distance between the tip and a potential obstacle, such as bone, but also visually locate the structures by combining transducer location tracking and synthetic aperture focusing...
April 2018: Journal of Medical Imaging
https://www.readbyqxmd.com/read/29628224/high-dynamic-range-ultrasound-application-for-imaging-tendon-pathology
#4
Yiming Xiao, Mathieu Boily, Hoda Sadat Hashemi, Hassan Rivaz
Raw ultrasound (US) signal has a very high dynamic range (HDR) and, as such, is compressed in B-mode US using a logarithmic function to fit within the dynamic range of digital displays. However, in some cases, hyper-echogenic tissue can be overexposed at high gain levels with the loss of hypo-echogenic detail at low gain levels. This can cause the loss of anatomic detail and tissue texture and frequent and inconvenient gain adjustments, potentially affecting the diagnosis. To mitigate these drawbacks, we employed tone mapping operators (TMOs) in HDR photography to create HDR US...
April 5, 2018: Ultrasound in Medicine & Biology
https://www.readbyqxmd.com/read/29620705/building-ultrasound-phantoms-with-modified-polyvinyl-chloride-a-comparison-of-needle-insertion-forces-and-sonographic-appearance-with-commercial-and-traditional-simulation-materials
#5
David Frederick Pepley, Cheyenne Cassel Sonntag, Rohan Sunil Prabhu, Mary Alice Yovanoff, David C Han, Scarlett Rae Miller, Jason Zachary Moore
INTRODUCTION: Training using ultrasound phantoms allows for safe introduction to clinical skills and is associated with improved in-hospital performance. Many materials have been used to simulate human tissue in phantoms including commercial manikins, agar, gelatin, and Ballistics Gel; however, phantom tissues could be improved to provide higher-fidelity ultrasound images or tactile sensation. This article describes a novel phantom tissue mixture of a modified polyvinyl chloride (PVC) polymer, mineral oil, and chalk powder and evaluates needle cutting and ultrasonic properties of the modified PVC polymer mixture compared with a variety of phantom tissues...
April 3, 2018: Simulation in Healthcare: Journal of the Society for Simulation in Healthcare
https://www.readbyqxmd.com/read/29610089/design-and-simulation-of-a-ring-shaped-linear-array-for-microultrasound-capsule-endoscopy
#6
Holly S Lay, Benjamin F Cox, Vipin Seetohul, Christine E M Demore, Sandy Cochran
Video capsule endoscopy (VCE) has significantly advanced visualization of the gastrointestinal tract since its introduction in the last 20 years. Work is now under way to combine VCE with microultrasound imaging. However, small maximum capsule dimensions, coupled with the electronics required to integrate ultrasound imaging capabilities, pose significant design challenges. This paper describes a simulation process for testing transducer geometries and imaging methodologies to achieve satisfactory imaging performance within the physical limitations of the capsule size and outlines many of the tradeoffs needed in the design of this new class of ultrasound capsule endoscopy (USCE) device...
April 2018: IEEE Transactions on Ultrasonics, Ferroelectrics, and Frequency Control
https://www.readbyqxmd.com/read/29610086/an-adaptive-synthetic-aperture-method-applied-to-ultrasound-tissue-harmonic-imaging
#7
Mehdi Haji Heidari Varnosfaderani, Babak Mohammadzadeh Asl, Saman Faridsoltani
In recent years, the minimum variance (MV) beamformer has been highly regarded since it provides high resolution and contrast in B-mode ultrasound imaging compared with nonadaptive delay-and-sum (DAS) beamformer. However, the performance of MV beamformer is degraded in the presence of the noise due to inaccurate estimation of the covariance matrix resulting in low-quality images. The conventional tissue harmonic imaging (THI) offers multiple advantages over conventional pulse-echo ultrasound imaging, including enhanced contrast resolution and improved axial and lateral resolutions, but low signal-to-noise ratio (SNR) is a major problem facing this imaging method, which uses a fixed transmit focus and dynamic receive focusing (DRF)...
April 2018: IEEE Transactions on Ultrasonics, Ferroelectrics, and Frequency Control
https://www.readbyqxmd.com/read/29610085/laser-generated-leaky-acoustic-waves-for-needle-visualization
#8
Kai-Wen Wu, Yi-An Wang, Pai-Chi Li
Ultrasound (US)-guided needle operation is usually used to visualize both tissue and needle position such as tissue biopsy and localized drug delivery. However, the transducer-needle orientation is limited due to reflection of the acoustic waves. We proposed a leaky acoustic wave method to visualize the needle position and orientation. Laser pulses are emitted on top of the needle to generate acoustic waves; then, these acoustic waves propagate along the needle surface. Leaky wave signals are detected by the US array transducer...
April 2018: IEEE Transactions on Ultrasonics, Ferroelectrics, and Frequency Control
https://www.readbyqxmd.com/read/29610083/a-spatial-coherence-approach-to-minimum-variance-beamforming-for-plane-wave-compounding
#9
Nghia Q Nguyen, Richard W Prager
A new approach to implement minimum variance distortionless response (MVDR) beamforming is introduced for coherent plane-wave compounding (CPWC). MVDR requires the covariance matrix of the incoming signal to be estimated and a spatial smoothing approximation is usually adopted to prevent this calculation from being underconstrained. In the new approach, we analyze MVDR as a spatial filter that decorrelates signals received at individual channels before summation. Based on the analysis, we develop two MVDR beamformers without using any spatial smoothing...
April 2018: IEEE Transactions on Ultrasonics, Ferroelectrics, and Frequency Control
https://www.readbyqxmd.com/read/29610070/ultrafast-ultrasound-imaging-with-cascaded-dual-polarity-waves
#10
Yang Zhang, Yuexin Guo, Wei-Ning Lee
Ultrafast ultrasound imaging using plane or diverging waves, instead of focused beams, has advanced greatly the development of novel ultrasound imaging methods for evaluating tissue functions beyond anatomical information. However, the sonographic signal-to-noise ratio (SNR) of ultrafast imaging remains limited due to the lack of transmission focusing, and thus insufficient acoustic energy delivery. We hereby propose a new ultrafast ultrasound imaging methodology with cascaded dual-polarity waves (CDWs), which consists of a pulse train with positive and negative polarities...
April 2018: IEEE Transactions on Medical Imaging
https://www.readbyqxmd.com/read/29610066/2-5-d-extended-field-of-view-ultrasound
#11
Qinghua Huang, Zhaozheng Zeng, Xuelong Li
Recently, the growing emphasis on medical ultrasound (US) has led to a rapid development of US extended field-of-view (EFOV) techniques. US EFOV techniques can be classified into three categories: 2-D US EFOV, 3-D US, and 3-D US EFOV. In this paper, we propose a novel EFOV method called 2.5-D US EFOV that combines both the advantages of the 2-D US EFOV and the 3-D US by generating a panorama on a curved image plane guided by a curved scanning trajectory of the US probe. In 2.5-D US EFOV, the real-time position and orientation of the US image plane can be recorded via an electromagnetic spatial sensor attached to the probe...
April 2018: IEEE Transactions on Medical Imaging
https://www.readbyqxmd.com/read/29604493/increasing-the-field-of-view-of-row-column-addressed-ultrasound-transducers-implementation-of-a-diverging-compound-lens
#12
Mathias Engholm, Christopher Beers, Hamed Bouzari, Jørgen Arendt Jensen, Erik Vilain Thomsen
The purpose of this work is to investigate compound lenses for row-column-addressed (RCA) ultrasound transducers for increasing the field-of-view (FOV) to a curvilinear volume region, while retaining a flat sole to avoid trapping air between the transducer sole and the patient, which would otherwise lead to unwanted reflections. The primary motivation behind this research is to develop a RCA ultrasound transducer for abdominal or cardiac imaging, where a curvilinear volume region is a necessity. RCA transducers provide 3-D ultrasound imaging with fewer channels than fully-addressed 2-D arrays (2N instead of N2 ), but they have inherently limited FOV...
March 24, 2018: Ultrasonics
https://www.readbyqxmd.com/read/29604086/em-enhanced-us-based-seed-detection-for-prostate-brachytherapy
#13
Ehsan Dehghan, Shyam Bharat, Cynthia Kung, Antonio Bonillas, Luc Beaulieu, Jean Pouliot, Jochen Kruecker
PURPOSE: Intraoperative dosimetry in low-dose-rate (LDR) permanent prostate brachytherapy requires accurate localization of the implanted seeds with respect to the prostate anatomy. Transrectal Ultrasound (TRUS) imaging, which is the main imaging modality used during the procedure, is not sufficiently robust for accurate seed localization. We present a method for integration of electromagnetic (EM) track-ing into LDR prostate brachytherapy procedure by fusing it with TRUS imaging for seed localization...
March 31, 2018: Medical Physics
https://www.readbyqxmd.com/read/29588854/experimental-study-of-beam-distortion-due-to-fiducial-markers-during-salvage-hifu-in-the-prostate
#14
Marina Bakaric, Eleanor Martin, Panayiotis S Georgiou, Benjamin T Cox, Heather Payne, Bradley E Treeby
Background: Prostate cancer is frequently treated using external beam radiation therapy (EBRT). Prior to therapy, the prostate is commonly implanted with a small number of permanent fiducial markers used to monitor the position of the prostate during therapy. In the case of local cancer recurrence, high-intensity focused ultrasound (HIFU) provides a non-invasive salvage treatment option. However, the impact of the fiducial markers on HIFU treatment has not been thoroughly studied to date...
2018: Journal of Therapeutic Ultrasound
https://www.readbyqxmd.com/read/29578414/a-mm-sized-wireless-implantable-device-for-electrical-stimulation-of-peripheral-nerves
#15
Jayant Charthad, Ting Chia Chang, Zhaokai Liu, Ahmed Sawaby, Marcus J Weber, Sam Baker, Felicity Gore, Stephen A Felt, Amin Arbabian
A wireless electrical stimulation implant for peripheral nerves, achieving >10× improvement over state of the art in the depth/volume figure of merit, is presented. The fully integrated implant measures just 2 mm × 3 mm × 6.5 mm (39 mm3 , 78 mg), and operates at a large depth of 10.5 cm in a tissue phantom. The implant is powered using ultrasound and includes a miniaturized piezoelectric receiver (piezo), an IC designed in 180 nm HV BCD process, an off-chip energy storage capacitor, and platinum stimulation electrodes...
April 2018: IEEE Transactions on Biomedical Circuits and Systems
https://www.readbyqxmd.com/read/29577016/iodinated-echogenic-glycol-chitosan-nanoparticles-for-x-ray-ct-us-dual-imaging-of-tumor
#16
Daeil Choi, Sangmin Jeon, Dong Gil You, Wooram Um, Jeong-Yeon Kim, Hong Yeol Yoon, Hyeyoun Chang, Dong-Eog Kim, Jae Hyung Park, Hyuncheol Kim, Kwangmeyung Kim
Development of biopolymer-based imaging agents which can access rapidly and provide detailed information about the diseases has received much attention as an alternative to conventional imaging agents. However, development of biopolymer-based nanomaterials for tumor imaging still remains challenging due to their low sensitivity and image resolution. To surmount of these limitations, multimodal imaging agents have been developed, and they were widely utilized for theranostic applications. Herein, iodine containing echogenic glycol chitosan nanoparticles are developed for x-ray computed tomography (CT) and ultrasound (US) imaging of tumor diagnosis...
2018: Nanotheranostics
https://www.readbyqxmd.com/read/29574795/in-vitro-evaluation-of-accuracy-of-dynamic-contrast-enhanced-ultrasound-dceus-based-parametric-perfusion-imaging-with-respiratory-motion-compensation
#17
Diya Wang, Mengnan Xiao, Yu Zhang, Zhe Su, Yujin Zong, Supin Wang, Mingxi Wan
PURPOSE: The accuracy of multi-parametric perfusion imaging (PPI) based on dynamic contrast-enhanced ultrasound is disturbed by the respiratory motion in some cases, especially during characterizing hemodynamic features of abdominal tumor angiogenesis. This study aimed to effectively remove those disturbances on PPI and evaluate its accuracy. METHOD: The respiratory motion-compensation (rMoCo) strategy in PPI was modified by employing non-negative matrix factorization combined with phase-by-phase compensation...
March 24, 2018: Medical Physics
https://www.readbyqxmd.com/read/29573255/internal-illumination-photoacoustic-computed-tomography
#18
Mucong Li, Bangxin Lan, Wei Liu, Jun Xia, Junjie Yao
We report a photoacoustic computed tomography (PACT) system using a customized optical fiber with a cylindrical diffuser to internally illuminate deep targets. The traditional external light illumination in PACT usually limits the penetration depth to a few centimeters from the tissue surface, mainly due to strong optical attenuation along the light propagation path from the outside in. By contrast, internal light illumination, with external ultrasound detection, can potentially detect much deeper targets. Different from previous internal illumination PACT implementations using forward-looking optical fibers, our internal-illumination PACT system uses a customized optical fiber with a 3-cm-long conoid needle diffuser attached to the fiber tip, which can homogeneously illuminate the surrounding space and substantially enlarge the field of view...
March 2018: Journal of Biomedical Optics
https://www.readbyqxmd.com/read/29566561/a-multimodality-imaging-compatible-insertion-robot-with-a-respiratory-motion-calibration-module-designed-for-ablation-of-liver-tumors-a-preclinical-study
#19
Dongrui Li, Zhigang Cheng, Gang Chen, Fangyi Liu, Wenbo Wu, Jie Yu, Ying Gu, Fengyong Liu, Chao Ren, Ping Liang
PURPOSE: To test the accuracy and efficacy of the multimodality imaging-compatible insertion robot with a respiratory motion calibration module designed for ablation of liver tumors in phantom and animal models. To evaluate and compare the influences of intervention experience on robot-assisted and ultrasound-controlled ablation procedures Methods: Accuracy tests on rigid body/phantom model with a respiratory movement simulation device and microwave ablation tests on porcine liver tumor/rabbit liver cancer were performed with the robot we designed or with the traditional ultrasound-guidance by physicians with or without intervention experience...
March 22, 2018: International Journal of Hyperthermia
https://www.readbyqxmd.com/read/29560717/heating-induced-by-therapeutic-ultrasound-in-the-presence-of-magnetic-nanoparticles
#20
Katarzyna Kaczmarek, Tomasz Hornowski, Martina Kubovcíkova, Milan Timko, Marceli Koralewski, Arkadiusz Józefczak
The efficiency of ultrasound hyperthermia for anti-cancer treatments such as radiotherapy or chemotherapy can be improved by using sonosensitizers, which are materials that enhance the attenuation and dissipation of acoustic energy. We propose the use of magnetic nanoparticles as sonosensitizers because of their biocompatibility, non-toxicity, and common use in several medical applications. A magnetic material was synthetized and then incorporated in the form of a magnetic fluid in agar tissue-mimicking phantoms...
March 21, 2018: ACS Applied Materials & Interfaces
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