Scholars@Duke
Olaf T. Von Ramm

Olaf T. Von Ramm

Thomas Lord Distinguished Professor of Engineering
Biomedical Engineering
olaf.vonramm@duke.edu
Duke Box 90281, Durham, NC 27708
2589 FCIEMAS, 101 Science Drive, Durham, NC 27708

Scholarly Works - Journal articles

Ultrasound Visualization and Recording of Transient Myocardial Vibrations.

Journal article Ultrasound Med Biol · June 2023 OBJECTIVE: A new visualization and recording method used to assess and quantitate autogenic high-velocity motions in myocardial walls to provide a new description of cardiac function is described. METHODS: The regional motion display (RMD) is based on high ... Full text Link to item Cite

Contractile Fronts In The Interventricular Septum: A Case For High Frame Rate Echocardiographic Imaging.

Journal article Ultrasound Med Biol · September 2020 The real time high frame rate (HFR) 2-dimensional ultrasound system, T5, at Duke University is capable of imaging at up to 1000 images per second for adult cardiac imaging. A method for detecting and visualizing the mechanical contraction fronts using HFR ... Full text Link to item Cite

Quantitative Parameters of High-Frame-Rate Strain in Patients with Echocardiographically Normal Function.

Journal article Ultrasound Med Biol · May 2019 Recently, we developed a high-frame-rate echocardiographic imaging system capable of acquiring images at rates up to 2500 per second. High imaging rates were used to quantify longitudinal strain parameters in patients with echocardiographically normal func ... Full text Link to item Cite

High-Frame-Rate Deformation Imaging in Two Dimensions Using Continuous Speckle-Feature Tracking.

Journal article Ultrasound Med Biol · November 2016 The study describes a novel algorithm for deriving myocardial strain from an entire cardiac cycle using high-frame-rate ultrasound images. Validation of the tracking algorithm was conducted in vitro prior to the application to patient images. High-frame-ra ... Full text Link to item Cite

Live high-frame-rate echocardiography.

Journal article IEEE Trans Ultrason Ferroelectr Freq Control · October 2015 We describe an advanced real-time high-speed echocardiographic system with live display while scanning. Images are acquired at rates up to 1000 per second for adult cardiac applications and are stored in computer memory. Images may be played back in slow m ... Full text Link to item Cite

In vivo real-time 3-D intracardiac echo using PMUT arrays.

Journal article IEEE transactions on ultrasonics, ferroelectrics, and frequency control · October 2014 Piezoelectric micromachined ultrasound transducer (PMUT) matrix arrays were fabricated containing novel through-silicon interconnects and integrated into intracardiac catheters for in vivo real-time 3-D imaging. PMUT arrays with rectangular apertures conta ... Full text Cite

Live volumetric imaging (LVI) intracardiac ultrasound catheter.

Journal article Cardiovascular revascularization medicine : including molecular interventions · May 2013 The Live Volumetric Imaging (LVI) catheter is capable of real-time 3D intracardiac echo (ICE) imaging, uniquely providing full volume sectors with deep penetration depth and high volume frame rate. The key enabling technology in this catheter is an integra ... Full text Cite

Harmonic source wavefront aberration correction for ultrasound imaging.

Journal article The Journal of the Acoustical Society of America · January 2011 A method is proposed which uses a lower-frequency transmit to create a known harmonic acoustical source in tissue suitable for wavefront correction without a priori assumptions of the target or requiring a transponder. The measurement and imaging steps of ... Full text Cite

Improved pulse-echo imaging performance for flexure-mode pMUT arrays

Journal article Proceedings IEEE Ultrasonics Symposium · December 1, 2010 Piezoelectric micromachined ultrasound transducers (pMUTs) are potentialcandidates for catheter-based ultrasound phased arrays. pMUTs consist of leadzirconate titanate (PZT) thin film membranes formed on silicon substrates andare operated in flexure mode b ... Full text Cite

Assessment of harmonic source correction for ultrasound medical imaging

Journal article Progress in Biomedical Optics and Imaging Proceedings of SPIE · September 24, 2010 Tissue velocity and attenuation inhomogeneities reduce ultrasound image quality in many patients. Over the years a number of methods have been developed to estimate the corrective delays necessary for phase aberration correction. Past methods were based on ... Full text Cite

The first harmonic as a known source for wavefront correction

Journal article Progress in Biomedical Optics and Imaging Proceedings of SPIE · June 19, 2009 It is demonstrated that distortion of a non-linearly generated first harmonic transmit beam due to a near-field aberrator is reduced as transmit pressure is increased. The first harmonic transmit beam is then used as a source for correction of aberration. ... Full text Cite

Theory and operation of 2-D array piezoelectric micromachined ultrasound transducers.

Journal article IEEE transactions on ultrasonics, ferroelectrics, and frequency control · November 2008 Piezoelectric micromachined ultrasound transducers (pMUTs) are a new approach for the construction of 2-D arrays for forward-looking 3-D intravascular (IVUS) and intracardiac (ICE) imaging. Two-dimensional pMUT test arrays containing 25 elements (5 x 5 arr ... Full text Cite

Three-dimensional motion measurements using feature tracking.

Journal article IEEE transactions on ultrasonics, ferroelectrics, and frequency control · April 2008 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 imp ... Full text Cite

Performance of flexure-mode pMUT 2D arrays

Journal article Proceedings IEEE Ultrasonics Symposium · December 1, 2007 We report on the performance characteristics of 2D pMUT arrays. 2D arrays suitable for diagnostic ultrasound imaging containing 81 elements were bulk micromachined in silicon substrates. The devices consisted of suspended PZT thin film membranes formed by ... Full text Cite

Classification of atherosclerotic rabbit aorta samples by mid-infrared spectroscopy using multivariate data analysis.

Journal article Journal of biomedical optics · March 2007 Atherosclerotic and normal rabbit aorta samples show a marked difference in chemical composition governed by the water, lipid, and protein content. The strongly overlapping infrared absorption features of the different constituents, and the complexity of t ... Full text Cite

Interactive volume rendering of real-time three-dimensional ultrasound images.

Journal article IEEE transactions on ultrasonics, ferroelectrics, and frequency control · February 2007 Real-time, three-dimensional (RT3D) ultrasound allows video frame rate volumetric imaging. The ability to acquire full three-dimensional (3-D) image data in real-time is particularly helpful for applications such as cardiac imaging, which require visualiza ... Full text Cite

Piezoelectric micromachined ultrasound transducer (pMUT) arrays for 3D imaging probes

Journal article Proceedings IEEE Ultrasonics Symposium · December 1, 2006 Piezoelectric micromachined ultrasound transducers (pMUTs) have been fabricated and characterized in this work as a new approach for manufacture of 2D arrays for forward-looking 3D intravascular (IVUS) and intracardiac (ICE) imaging. Two-dimensional pMUT a ... Full text Cite

C-mode real-time tomographic reflection for a matrix array ultrasound sonic flashlight.

Journal article Academic radiology · May 2005 Rationale and objectivesReal-time tomographic reflection (RTTR) permits in situ visualization of tomographic images so that natural hand-eye coordination can be used directly during invasive procedures. The method uses a half-silvered mirror to me ... Full text Cite

Left ventricular wall motion analysis using real-time three-dimensional ultrasound.

Journal article Ultrasound in medicine & biology · February 2005 This study tested the ability of real-time 3-D (RT 3-D) echocardiography to detect and delineate regions of abnormal contraction (akinesia or dyskinesia) in a canine model of regional myocardial injury and to develop methods to simplify injury assessments. ... Full text Cite

Real-time 3-dimensional echocardiography for quantification of the difference in left ventricular versus right ventricular stroke volume in a chronic animal model study: Improved results using C-scans for quantifying aortic regurgitation.

Journal article Journal of the American Society of Echocardiography : official publication of the American Society of Echocardiography · August 2004 ObjectiveThe purpose of our study was to test the applicability of calculating the difference between left ventricular (LV) and right ventricular (RV) stroke volume (SV) for assessing the severity of aortic (Ao) regurgitation (AR) using a real-tim ... Full text Cite

Interactive rendering of real-time volumetric ultrasound images

Journal article 2004 2nd IEEE International Symposium on Biomedical Imaging Macro to Nano · January 1, 2004 Volumetric ultrasound imaging opens the door to a variety of diagnostic and interventional investigations. A key to the utility of volumetric ultrasound imaging is the ability to produce high quality displays of the target in real time as data is acquired. ... Full text Cite

Real-time three-dimensional echocardiography to construct clinically ready, load-independent indices of myocardial contractile performance.

Journal article J Am Soc Echocardiogr · September 2003 BACKGROUND: Real-time 3-dimensional echocardiography (RT3DE) reliably determines intracardiac chamber volumes without left ventricular (LV) geometric assumptions, yet clinical assessment of contractile performance is often on the basis of potentially inacc ... Full text Link to item Cite

RV functional imaging: 3-D echo-derived dynamic geometry and flow field simulations.

Journal article Am J Physiol Heart Circ Physiol · January 2003 We describe a novel functional imaging approach for quantitative analysis of right ventricular (RV) blood flow patterns in specific experimental animals (or humans) using real-time, three-dimensional (3-D) echocardiography (RT3D). The method is independent ... Full text Link to item Cite

C-mode real time tomographic reflection for a matrix array ultrasound sonic flashlight

Journal article Lecture Notes in Computer Science · January 1, 2003 Real Time Tomographic Reflection (RTTR), permits in situ visualization of tomographic images, so that natural hand-eye coordination can be employed directly during invasive procedures. The method merges the visual outer surface of the patient with a simult ... Full text Cite

Ultrasonic transducer simulation and field visualization 2nd joint conference of the IEEE engineering in medicine and biology society and the biomedical engineering society

Journal article Annual International Conference of the IEEE Engineering in Medicine and Biology Proceedings · December 1, 2002 The process of designing an ultrasonic phased array benefits from the ability to quickly view the effects of transducer modifications. This is particularly important for sparse arrays, where small changes in element placement or symmetry can have large eff ... Cite

Left ventricle function analysis with real-time three-dimensional ultrasound

Journal article Annual International Conference of the IEEE Engineering in Medicine and Biology Proceedings · December 1, 2002 Conventional B-mode echocardiography is commonly used to assess ventricular function, but it is inherently limited by its tomographic nature and operator dependence for obtaining standard views. Use of real-time three-dimensional ultrasound (RT3D) overcome ... Cite

Design and construction of an evanescent optical wave device for the recanalization of vessels

Journal article Nuclear Instruments and Methods in Physics Research Section A Accelerators Spectrometers Detectors and Associated Equipment · November 21, 2001 Removing atherosclerotic material without transecting the vessel wall is a common problem for vascular surgeons and interventional cardiologists. The goal of this project is to design and construct a device that uses evanescent optical waves for precise, c ... Full text Cite

Quantification of aortic regurgitation by real-time 3-dimensional echocardiography in a chronic animal model: computation of aortic regurgitant volume as the difference between left and right ventricular stroke volumes.

Journal article Journal of the American Society of Echocardiography : official publication of the American Society of Echocardiography · November 2001 BackgroundThe accuracy of conventional 2-dimensional echocardiographic and Doppler techniques for the quantification of valvular regurgitation remains controversial. In this study, we examined the ability of real-time 3-dimensional (RT3D) echocard ... Full text Cite

Real-time, volumetric echocardiography: usefulness of volumetric scanning for the assessment of cardiac volume and function.

Journal article J Cardiol · 2001 BACKGROUND: A novel imaging system has been introduced which uses a dedicated two-dimensional echo probe for rapid beam forming to scan a pyramidal volume in real time. Real-time volumetric echocardiography has the potential to determine accurate cardiovas ... Link to item Cite

Anatomic validation of a novel method for left ventricular volume and mass measurements with use of real-time 3-dimensional echocardiography.

Journal article Journal of the American Society of Echocardiography : official publication of the American Society of Echocardiography · January 2001 Assessment of left ventricular (LV) volumes and mass is a critical element in the evaluation of patients with cardiovascular disease. However, most non-invasive methods used for the quantitative measurements of LV volume and mass have important intrinsic l ... Full text Cite

Real-time volumetric echocardiography: the technology and the possibilities.

Journal article Echocardiography · November 2000 The heart is a dynamic organ with complexities in its shape. As such, it places special demands on three-dimensional techniques for reconstruction. Real-time volumetric echocardiography, which is based on phased array and parallel processing principles to ... Full text Link to item Cite

Angular scatter ultrasound imaging of wavelength scale targets.

Journal article The Journal of the Acoustical Society of America · October 2000 A bistatic ultrasound imaging system is demonstrated that uses two 32-element linear phased array transducers oriented at an angle of 40 degrees to one another. The system simultaneously acquires and displays in real time one conventional backscatter image ... Full text Cite

2-D arrays.

Journal article Ultrasound in medicine & biology · May 2000 Full text Cite

Design and characterization of a real-time angular scatter ultrasound imaging system.

Journal article IEEE transactions on ultrasonics, ferroelectrics, and frequency control · January 2000 A novel ultrasound imaging system has been implemented using two 32-element linear phased array transducers oriented at an angle of 40 degrees to one another. The system simultaneously acquires and displays, in real time, a conventional backscatter image a ... Full text Cite

Real-time three-dimensional echocardiography for measurement of left ventricular volumes.

Journal article The American journal of cardiology · December 1999 Left ventricular (LV) volumes are important prognostic indexes in patients with heart disease. Although several methods can evaluate LV volumes, most have important intrinsic limitations. Real-time 3-dimensional echocardiography (RT3D echo) is a novel tech ... Full text Cite

Real-time, three-dimensional echocardiography: feasibility of dynamic right ventricular volume measurement with saline contrast.

Journal article Am Heart J · May 1999 BACKGROUND: The asymmetry and complex shape of the right ventricle have made it difficult to determine right ventricular (RV) volume with 2-dimensional echocardiography. Three-dimensional cardiac imaging improves visualization of cardiac anatomy but is als ... Full text Link to item Cite

FLASH correlation: a new method for 3-D ultrasound tissue motion tracking and blood velocity estimation.

Journal article IEEE transactions on ultrasonics, ferroelectrics, and frequency control · January 1999 We report a new method for tracking tissue motion and blood flow in three dimensions (3-D) using successive volumetric ultrasound scans. The method is based on combining the concepts of feature tracking and 3-D correlation search to achieve a compromise be ... Full text Cite

3D ultrasound tissue motion tracking using correlation search.

Journal article Ultrasonic imaging · July 1998 Several methods for ultrasound tissue motion tracking and blood velocity estimation have been proposed and clinically applied. While providing valuable information to the clinician that was not obtainable from B-mode anatomical imaging, these methods still ... Full text Cite

Real-time three-dimensional echocardiography for determining right ventricular stroke volume in an animal model of chronic right ventricular volume overload.

Journal article Circulation · May 19, 1998 BACKGROUND: The lack of a suitable noninvasive method for assessing right ventricular (RV) volume and function has been a major deficiency of two-dimensional (2D) echocardiography. The aim of our animal study was to test a new real-time three-dimensional ( ... Full text Link to item Cite

Rotary pumps: new developments and future perspectives.

Journal article ASAIO journal (American Society for Artificial Internal Organs : 1992) · May 1998 Full text Cite

Real-time 3D ultrasound: A new look at the heart

Journal article Journal of Cardiovascular Diagnosis and Procedures · January 1, 1998 Matrix array ultrasound is a medical imaging modality in which a 3D volume is scanned electronically without physically moving the transducer, permitting rapid continuous 3D scanning of the heart. Unlike reconstructive 3D ultrasound, which relies on physic ... Cite

Detection and quantification of true 3D motion components of the myocardium using 3D speckle tracking in volumetric ultrasound scans: simulations and initial experimental results

Journal article Proceedings of SPIE - The International Society for Optical Engineering · 1997 We present a new method for detecting and tracking tissue motion in 3D. The method is based on the concept of tracking speckle patterns in 3D using the sum absolute difference (SAD) technique. One potential application of this method is to study the 3D mot ... Full text Link to item Cite

Ultrasound three-dimensional velocity measurements by feature tracking

Journal article IEEE Transactions on Ultrasonics Ferroelectrics and Frequency Control · December 1, 1996 This article describes a new angle-independent method suitable for three-dimensional (3-D) blood flow velocity measurement that tracks features of the ultrasonic speckle produced by a pulse echo system. In this method, a feature is identified and followed ... Full text Cite

Comparison of contrast in backscatter and angular scatter ultrasonic images

Journal article Proceedings of the IEEE Ultrasonics Symposium · December 1, 1996 A real time angular scatter imaging system has been implemented on the Duke phased array scanner. One 32 element linear phased array transducer is used as the transmit aperture, and a second 32 element array is used as the receiver. The receive array is po ... Cite

Towards the volumetricardiogram: volume determination of cardiac chambers using 3D matrix-array ultrasound

Journal article Proceedings of SPIE the International Society for Optical Engineering · December 1, 1995 Matrix-array ultrasound is a new medical imaging modality that steers an ultrasound beam electronically in three dimensions. It is the first imaging modality that can view the heart in 3D in real time, making possible the `volumetricardiogram,' i.e., conti ... Cite

Flow integration transform: detecting shapes in matrix-array 3D ultrasound data

Journal article Proceedings of SPIE the International Society for Optical Engineering · December 1, 1995 Matrix-array ultrasound produces real-time 3D images of the heart, by employing a square array of transducers to steer the ultrasound beam in three dimensions electronically with no moving parts. Other 3D modalities such as MR, MUGA, and CT require the use ... Cite

Speckle structure in three dimensions.

Journal article The Journal of the Acoustical Society of America · July 1995 Ultrasound speckle has long been recognized as a noise source in diagnostic imaging. The advent of three-dimensional imaging and flow detection requires the characterization of the three-dimensional acoustical speckle pattern. Ultrasound data were acquired ... Full text Cite

Feasibility study for a two-dimensional diagnostic ultrasound velocity mapping system.

Journal article Ultrasound in medicine & biology · January 1995 A receive beam-tracking technique is introduced for simultaneously measuring more than one dimension of an existing velocity vector in medical ultrasound. By using flexible beamforming and a conventional linear-array transducer, vectors can be measured at ... Full text Cite

Real-Time Angular Scatter Imaging System for Improved Tissue Contrast in Diagnostic Ultrasound Images

Journal article IEEE Transactions on Ultrasonics Ferroelectrics and Frequency Control · January 1, 1994 A new type of real-time ultrasound imaging system has been developed. In contrast to conventional systems, which process only echoes scattered directly back from tissue to form an image, this system images tissue by displaying energy scattered at other ang ... Full text Cite

Optical transducer for reception of ultrasonic waves.

Journal article The Journal of the Acoustical Society of America · February 1993 A new optical transducer for the detection of acoustic pressure in the diagnostic ultrasound frequency range is described. This transducer is based on the modulation of an evanescent light field by the incident acoustic energy. Theoretical design considera ... Full text Cite

National Science Foundation/Engineering Research Center for emerging cardiovascular technologies

Journal article Proceedings of the IEEE · 1993 The mission of the National Science Foundation/Engineering Research Center for Emerging Cardiovascular Technologies is to lead discovery and innovation in custom-integrated electronics, sensors, systems design, and simulation to develop a new generation of ... Full text Cite

Two-dimensional arrays for medical ultrasound.

Journal article Ultrasonic imaging · July 1992 The design, fabrication and evaluation of two-dimensional transducer arrays are described for medical ultrasound imaging. A 4 x 32, 2.8 MHz array was developed to use new signal processing techniques for improved B-scan imaging including elevation focusing ... Full text Cite

High-speed ultrasound volumetric imaging system. II. Parallel processing and image display.

Journal article IEEE transactions on ultrasonics, ferroelectrics, and frequency control · January 1991 For pt.I see ibid., vol.38, no.2, p.100-8 (1991). The authors describe the design, application, and evaluation of parallel processing to the high-speed volumetric ultrasound imaging system. The scanner produces images analogous to an optical camera or the ... Full text Cite

High-speed ultrasound volumetric imaging system. I. Transducer design and beam steering.

Journal article IEEE transactions on ultrasonics, ferroelectrics, and frequency control · January 1991 Transducer design and phased array beam steering are developed for a volumetric ultrasound scanner that enables the 3-D visualization of dynamic structures in real time. The authors describe the design considerations and preliminary evaluation of a high-sp ... Full text Cite

Improved real time volumetric ultrasonic imaging system

Journal article Proceedings of SPIE the International Society for Optical Engineering · January 1, 1991 A real time volumetric ultrasonic imaging system has been improved through the use of parallel processing in two dimensions. The imaging system uses pulse-echo phased array principles to steer a two-dimensional transducer array in a pyramidal scan format. ... Cite

Real-time, three-dimensional echocardiography: feasibility and initial use.

Journal article Echocardiography · January 1991 The purpose of this article is to review new approaches to three-dimensional acquisition and presentation of echocardiographic data. New three-dimensional phased-array devices hold great promise for the development and application of new descriptors for le ... Full text Link to item Cite

Real-time 3D ultrasonic data acquistion

Journal article Proceedings of the Annual Conference on Engineering in Medicine and Biology · December 1, 1990 The research program of Unit 2.1A, Real-Time 3-D Ultrasonic Data Acquisition, of the National Science Foundation/Engineering Research Center (NSF/ERC) is described. The unit's overall objective is to develop noninvasive ultrasonic means to study and assess ... Cite

Real time volumetric ultrasound imaging system.

Journal article Journal of digital imaging · November 1990 A real time volumetric ultrasound imaging system has been developed for medical diagnosis. The scanner produces images analogous to an optical camera and supplies more information than conventional sonograms. Potential medical applications include improved ... Full text Cite

Real time volumetric ultrasound imaging system

Journal article Proceedings of SPIE the International Society for Optical Engineering · July 1, 1990 A real time volumetric ultrasound imaging system has been developed for medical diagnosis. The scanner produces images analogous to an optical camera or the human eye and supplies more information than conventional sonograms. Potential medical applications ... Full text Cite

Laboratory evaluation of the Maltese cross processor: Speckle reduction for circular transducers

Journal article Ultrasonics Symposium Proceedings · December 1, 1989 An online signal-processing technique to reduce speckle noise in ultrasound images is described. In the imaging system, a focused piston transducer is divided into 32 sectors. In the receive mode, parallel signal processing arranges the sectors into eight ... Cite

Angle independent ultrasonic blood flow detection by frame-to-frame correlation of B-mode images.

Journal article Ultrasonics · September 1988 We have previously reported initial clinical results of a novel blood velocity imaging technique utilizing a two-dimensional correlation search applied to consecutively acquired echoes. In this paper, we describe both the physical principles underlying thi ... Full text Cite

The Maltese cross processor: speckle reduction for circular transducers.

Journal article Ultrasonic imaging · July 1988 A new online signal processing technique is described to reduce speckle noise in ultrasound images. In the imaging system, a focused piston transducer is divided into thirty-two sectors. In the receive mode, parallel signal processing arranges the sectors ... Full text Cite

Ultrasound bioeffects and regulatory issues: an introduction for the echocardiographer.

Journal article Journal of the American Society of Echocardiography : official publication of the American Society of Echocardiography · May 1988 Full text Cite

Fundamentals of current doppler technology

Journal article Ultrasound Quarterly · January 1, 1988 Development of “Duplex” Doppler systems has spurred an increasing interest in ultrasound analysis of vessel anatomy, pathology, and flow physiology. Numerous systems are available, utilizing a variety of different approaches in providing flow velocity and ... Full text Cite

MEASUREMENT OF LOCAL SPECKLE PATTERN DISPLACEMENT TO TRACK BLOOD FLOW IN TWO DIMENSIONS.

Journal article Ultrasonics Symposium Proceedings · December 1, 1987 A velocity imaging technique is described which operates on the envelope-detected echo signal and uses a two-dimensional correlation search method. Several experiments were performed to define the potentials and limitations of this technique. The results i ... Cite

Angle independent ultrasonic detection of blood flow.

Journal article IEEE transactions on bio-medical engineering · December 1987 Full text Cite

Speckle reduction achievable by spatial compounding and frequency compounding: Experimental results and implications for target detectability

Journal article Proceedings of SPIE the International Society for Optical Engineering · September 10, 1987 The degree of speckle reduction achievable by spatial and frequency compounding is a function of the rates of speckle pattern change induced by varying the imaging system’s illumination angle and acoustic frequency, respectively. We have measured these rat ... Full text Cite

SPECKLE SNR VS. LATERAL RESOLUTION IN ULTRASOUND IMAGING: WHAT'S THE TRADEOFF?

Journal article Ultrasonics Symposium Proceedings · December 1, 1986 The rates of ultrasonic B-mode speckle pattern changes are measured as a function of changes in the imaging angle under a variety of experimental conditions. The results of these experiments were used to design an imaging system that optimizes speckle redu ... Cite

A quantitative approach to speckle reduction via frequency compounding.

Journal article Ultrasonic imaging · July 1986 Coherent speckle is a source of image noise in ultrasonic B-mode imaging. The use of multiple imaging frequencies has been suggested as a technique for speckle contrast reduction. This technique involves the averaging of images whose speckle patterns have ... Full text Cite

Real-time orthogonal mode scanning of the heart. I. System design.

Journal article J Am Coll Cardiol · June 1986 A necessary percursor to real-time three-dimensional echocardiographic imaging is the ability to obtain multiple planes of acoustic data simultaneously. A new ultrasound imaging technique facilitates the display of two real-time orthogonal B-mode images (O ... Full text Link to item Cite

Phased array ultrasound imaging through planar tissue layers.

Journal article Ultrasound in medicine & biology · March 1986 Conventional ultrasound imaging devices are designed based on the assumption of a homogeneous tissue medium of constant acoustic velocity = 1540 m/sec. However, the body consists of tissue layers of varying thicknesses and velocities which range from 1470 ... Full text Cite

Speckle reduction in medical ultrasound via spatial compounding

Journal article Proc. SPIE - Int. Soc. Opt. Eng. (USA) · 1986 In order to design improved spatial compounding ultrasound scanning systems it is necessary to determine the correlation of speckle patterns as a function of aperture translation. The authors have conducted experiments measuring the speckle correlation as ... Cite

SPECKLE PATTERN CHANGES WITH VARYING ACOUSTIC FREQUENCY: EXPERIMENTAL MEASUREMENT AND IMPLICATIONS FOR FREQUENCY COMPOUNDING.

Journal article Ultrasonics Symposium Proceedings · January 1, 1986 The authors have measured the rates of ultrasonic B-mode speckle pattern changes as a function of the change in center frequency of the transmitted acoustical pulse under a variety of experimental conditions. Experimental results agree with a previous theo ... Full text Cite

Speckle pattern correlation with lateral aperture translation: experimental results and implications for spatial compounding.

Journal article IEEE transactions on ultrasonics, ferroelectrics, and frequency control · January 1986 Full text Cite

Explososcan: A parallel processing technique for high speed ultrasound imaging with linear phased arrays

Journal article Proceedings of SPIE the International Society for Optical Engineering · June 11, 1985 The data acquisition rate in medical ultrasonic imaging devices is limited by the acoustic propagation velocity in the tissues. Typically in such machines the image lines are produced sequentially one line per transmitted pulse. A parallel processing schem ... Full text Cite

Explososcan: a parallel processing technique for high speed ultrasound imaging with linear phased arrays.

Journal article The Journal of the Acoustical Society of America · April 1984 The data acquisition rate in medical ultrasonic imaging devices is limited by the acoustic propagation velocity in the tissues. Typically in such machines the image lines are produced sequentially one line per transmitted pulse. A parallel processing schem ... Full text Cite

Pulsed Doppler spectral analysis of bounded fluid jets.

Journal article Ultrasound Med Biol · 1984 To test the hypothesis that pulsed Doppler ultrasound spectral properties of bounded fluid jets related to orifice size, in vitro examinations were performed using a hydraulic simulator (standpipe, compliant receiving chamber, and variable round orifice). ... Full text Link to item Cite

Beam steering with linear arrays.

Journal article IEEE transactions on bio-medical engineering · August 1983 Full text Cite

Beam steering with linear arrays

Journal article IEEE Trans. Biomed. Eng. (USA) · 1983 The principles and techniques of real-time imaging with phased array ultrasound scanners are reviewed. Topics include (1) the geometric optics of beam steering and focusing with a linear array in the transmit and receive modes; (2) limitations on image dat ... Cite

Compound scanning with a phased array.

Journal article Ultrasonic imaging · April 1982 Full text Cite

ANOMALOUS QUANTIZATION ERROR LOBES IN PHASED ARRAY IMAGES.

Journal article Acoustical Imaging Proceedings of the International Symposium · January 1, 1982 Full text Cite

Combined doppler and phased-array echocardiographic estimation of cardiac output.

Journal article Circulation · February 1981 The capability of a pulsed Doppler flowmeter combined with a phased-array imaging system to measure volume flow was tested in vitro and in patients undergoing cardiac catheterization. The Doppler-phased-array system (DPA) was used to determine vessel diame ... Full text Link to item Cite

Delay Quantization Error in Phased Array Images

Journal article IEEE Transactions on Sonics and Ultrasonics · January 1, 1981 Time quantization errors in phased array systems can cause increased sidelobe amplitude, thereby limiting the dynamic range of the ultrasound system. A simulation program predicting the position and amplitude of these anomalous quantization error grating l ... Full text Cite

DELAY QUANTIZATION ERROR IN PHASED ARRAY IMAGES.

Journal article IEEE transactions on sonics and ultrasonics · 1981 Time quantization errors in phased array systems can cause increased sidelobe amplitude, thereby limiting the dynamic range of the ultrasound system. A simulation program predicting the position and amplitude of these anomalous quantization error grating l ... Cite

ON GREATER VISUALIZATION OF MYOCARDIUM.

Journal article undefined · December 1, 1980 Cite

Abdominal and obstetric applications of a dynamically focused phased array real time ultrasound system.

Journal article Clinical radiology · May 1980 Abdominal and obstetric applications of a dynamically focused phased array real time ultrasonic system are described. This work was performed utilising both the Thaumascan (two-dimensional, high resolution, actual time, ultrasound, multi-element array scan ... Full text Cite

Prospects and limitations of diagnostic ultrasound

Journal article Proceedings of SPIE the International Society for Optical Engineering · December 26, 1979 The current state of medical diagnostic ultrasound imaging is analyzed including discussions of present limitations and possible solutions of these problems. Ultrasound is unique in that tomographic images are formed from mechanical energy reflected from t ... Full text Cite

ADAPTIVE ULTRASOUND CEPHALIC IMAGING SYSTEM.

Journal article undefined · December 1, 1979 Cite

PHASE ARRAY COMPOUND SCANNING.

Journal article undefined · December 1, 1979 Cite

ANGULAR RESPONSE OF PIEZOELECTRIC ELEMENTS IN PHASED ARRAY ULTRASOUND SCANNERS.

Journal article IEEE Transactions on Sonics and Ultrasonics · 1979 In the design of phased linear array sector scanners for medical applications, it is important to preserve uniform response at each angle throughout the sector scan of plus or minus 45 degree . Examination of linear array transducers showed reduced transmi ... Cite

Angular Response of Piezoelectric Elements in Phased Array Ultrasound Scanners

Journal article IEEE Transactions on Sonics and Ultrasonics · January 1, 1979 In the design of phased linear array sector scanners for medical applications, it is important to preserve uniform response at each angle throughout the sector scan of ± 45°. Examination of linear array transducers showed reduced transmit pressure and rece ... Full text Cite

Principles and applications of a dynamically focused phased array real time ultrasound system.

Journal article Journal of clinical ultrasound : JCU · December 1978 The physical principles and clinical applications of a high-resolution, dynamically focused phased-array real time ultrasound are described. Advantages of the real time technique include rapid survey capability, efficient selection of an appropriate tomogr ... Full text Cite

Real time ultrasound tomography of the adult brain.

Journal article Stroke · 1978 Initial clinical results are reported from a new real time, 2-dimensional ultrasound scanner modified for adult cephalic applications. An optimized transducer design and the use of the dynamically focused phased array imaging system have resulted in ultras ... Full text Link to item Cite

A Multiple Frequency Array for Improved Diagnostic Imaging

Journal article IEEE Transactions on Sonics and Ultrasonics · January 1, 1978 Cost and complexity of phased array diagnostic ultrasound imaging systems is related to the number of parallel channels during both transmit and receive. If the total number of active elements within a given aperture is reduced so that fewer parallel chann ... Full text Cite

Dynamic cardiac imaging using a focused, phased-array ultrasound system.

Journal article Am J Med · July 1977 A two-dimensional ultrasound imaging system capable of producing high resolution, cross-sectional images of the heart in real-time has been developed. This system relies upon phased-array principles to rapidly steer and focus the ultrasound beam through th ... Full text Link to item Cite

A comparison of real-time, two dimensional echocardiography and cineangiography in detecting left ventricular asynergy.

Journal article Circulation · January 1977 Left ventricular wall motion was assessed in 105 consecutive patients both invasively, using biplane cineangiography, and noninvasively, by a real-time, phased-array, two-dimensional echocardiography system. Ventricular wall motion in five anatomic areas o ... Full text Link to item Cite

Clinical results of real-time ultrasonic scanning of the heart using a phased array system.

Journal article Yale J Biol Med · 1977 This report describes the operating characteristics and initial clinical results of a new echocardiographic system that produces real-time, high resolution, cross-sectional images of the heart. This system relies upon phased-array principles to rapidly ste ... Link to item Cite

Mitral valve prolapse. Two-dimensional echocardiographic and angiographic correlation.

Journal article Circulation · November 1976 In order to define baseline descriptive criteria for the diagnosis of mitral valve prolapse with cross-sectional echocardiography, 49 patients undergoing catheterization were examined by a real-time, two-dimensional phased array echocardiographic imaging s ... Full text Link to item Cite

Echocardiographic evaluation of tricuspid valve endocarditis: an M mode and two dimensional study.

Journal article Am J Cardiol · October 1976 Standard M mode echocardiography and a new real time two dimensional echocardiographic imaging system were utilized to follow the progressive anatomic destruction of the tricuspid valve in a patient with bacterial endocarditis. The initial two dimensional ... Full text Link to item Cite

Gray scale imaging with complex tgc and transducer arrays

Journal article Proceedings of SPIE the International Society for Optical Engineering · March 25, 1976 Ultrasound imaging of soft tissues places severe demands on the design of imaging systems because of the large range of echo amplitudes which may be encountered at any point in the body. Simple TGC curves are often inadequate in producing optimum gray scal ... Full text Cite

Dynamic cardiac imaging using a phased-array transducer system

Journal article Proceedings of SPIE the International Society for Optical Engineering · March 11, 1976 Full text Cite

Cardiac imaging using a phased array ultrasound system. II. Clinical technique and application.

Journal article Circulation · February 1976 A new two-dimensional ultrasound imaging system capable of producing high resolution tomographic images of the heart in real time has been developed. This system relies on phased array principles to rapidly steer the ultrasound beam through the structures ... Full text Link to item Cite

Cardiac imaging using a phased array ultrasound system. I. System design.

Journal article Circulation · February 1976 A new two-dimensional, real-time, high resolution ultrasound imaging system is described. This system uses a linear array of ultrasound transducers to generate tomographic images of the heart in a circular sector format. Phased array techniques allow rapid ... Full text Cite

Dynamic cardiac imaging using a phased array transducer system

Journal article Proc Soc Photo Opt Instr Engin · January 1, 1975 Cite

ACOUSTICAL IMAGING WITH A LINEAR PHASED ARRAY.

Journal article undefined · January 1, 1975 The relation of imaging speed and sensitivity to the nature of image processing and the degree to which parallel processing is employed are considered. The limitations imposed on image resolution and ambiguity by the use of a discretely sampled aperture ar ... Full text Cite

A phased array ultrasound system for cardiac imaging

Journal article Excerpta Medica Ics no 363 · January 1, 1975 This report describes the design considerations, performance characteristics and initial clinical results of a new, high-resolution, real-time, two-dimensional ultrasound sector scanner designed specifically for cardiac use. Such a system is unique as it r ... Cite

CARDIOVASCULAR DIAGNOSIS WITH REAL TIME ULTRASOUND IMAGING.

Journal article Acoust Hologr · January 1, 1975 Real-time imaaging system is described that relies on phased array principles to steer and focus the ultrasound beam in the near field of a linear array of ultrasound transducers. Underlying the development of this system were several design considerations ... Full text Cite

DYNAMIC CARDIAC IMAGING USING A PHASED-ARRAY TRANSDUCER SYSTEM.

Journal article SPIE Semin Proc · January 1, 1975 This report describes the design considerations, performance characteristics and initial clinical results of a new, high-resolution, real-time, two-dimensional ultrasound sector scanner designed specifically for cardiac use. Such a system is unique as it r ... Cite

SAMPLED APERTURE TECHNIQUES APPLIED TO B-MODE ECHOENCEPHALOGRAPHY.

Journal article Acoust Hologr · January 1, 1975 An electronically steered and focused multielement transducer array is used in an attempt to minimize acoustic aberrations caused by skull thickness variations. Aberrations like this have thus far limited practical utilization of B-mode scanners in clinica ... Full text Cite

NEW ULTRASOUND IMAGING TECHNIQUE EMPLOYING TWO-DIMENSIONAL ELECTRONIC BEAM STEERING.

Journal article · December 1, 1974 A new ultrasound imaging system which removes or substantially reduces many previous limitations has been developed. This imaging system is based on phased array principles rather than the usual mechanical positioning to scan the ultrasound beam through th ... Cite

NEW ULTRASOUND IMAGING TECHNIQUE EMPLOYING TWO-DIMENSIONAL ELECTRONIC BEAM STEERING.

Journal article · January 1, 1974 A new ultrasound imaging system which removes or substantially reduces many previous limitations has been developed. This imaging system is based on phased array principles rather than the usual mechanical positioning to scan the ultrasound beam through th ... Cite

REAL TIME TWO-DIMENSIONAL ECHOCARDIOGRAPHY.

Journal article SPIE Semin Proc · January 1, 1974 A description is given of an ultrasound imaging system which permits visualization of two-dimensional cardiac anatomy in real time. This system relies on phased array principles rather than mechanical means to rapidly steer the ultrasound beam through the ... Cite

ACOUSTICAL HOLOGRAPHY, VOLUME 4.

Journal article Acoust Hologr · January 1, 1972 Following is the continuation of the list of titles and authors: Experimental Holographic Acoustic Imaging System. By N. Booth and B. Saltzer. First-Arrival Seismic Holograms. By G. L. Fitspatrick. Analysis of Varius Ultrasonic Holographic Imaging Methods ... Cite

Coherent optical processing of optical data

Journal article Nouvelle Revue D Optique Appliquee · December 1, 1970 Full text Cite

THREE TECHNIQUES OF SPECTRAL ANALYSIS IN ELECTROCARDIOGRAMS

Journal article · January 1, 1970 Use of computer program, optical processor, and conventional spectrum analyzer techniques. Digest of paper. ... Cite