Patrick D. Wolf

Conference IEEE International Ultrasonics Symposium Ius · November 1, 2016 Momentum created by a high intensity acoustic wave emitted in intracardiac echocardiography (ICE) Acoustic Radiation Force Impulse (ARFI) imaging sequences is absorbed by the backing material of the catheter causing a kickback motion. This study was design ... Full text Cite

M-mode ARFI imaging demonstrates the effect of coronary perfusion on cardiac stiffness

Conference IEEE International Ultrasonics Symposium Ius · October 20, 2014 Myocardial stiffness is an important clinical indicator of cardiac function. One of the contributors to stiffness in the heart is coronary perfusion. The interaction between cardiac tissue and coronary vasculature has been studied for several decades using ... Full text Cite

The effect of acute coronary perfusion change on cardiac function measured by Shear Wave Elasticity Imaging.

Conference Annual International Conference of the IEEE Engineering in Medicine and Biology Society. IEEE Engineering in Medicine and Biology Society. Annual International Conference · January 2014 The possibility of measuring cardiac function noninvasively has generated wide interest in elastography imaging techniques. Shear Wave Elasticity Imaging (SWEI) is an ultrasound-based elastography technique used to measure stiffness of tissues. While this ... Full text Cite

Confirmation of cardiac radiofrequency ablation treatment using intra-procedure acoustic radiation force impulse imaging

Conference IEEE International Ultrasonics Symposium Ius · December 1, 2012 Recurrence of atrial fibrillation after transcatheter ablation (TCA) is common because there is no imaging modality that can visually confirm the presence of radiofrequency ablation (RFA) lesions. We have previously shown that acoustic radiation force impu ... Full text Cite

Feasibility and safety of transthoracic cardiac acoustic radiation force impulse imaging methods

Conference IEEE International Ultrasonics Symposium Ius · December 1, 2012 This work examines clinical feasibility of using non-invasive transthoracic echocardiography techniques to visualize temporal variations of stiffness through the cardiac cycle using acoustic radiation force impulse (ARFI) imaging. © 2012 IEEE. ... Full text Cite

Intracardiac ARF-driven shear wave velocimetry to estimate regional myocardial stiffness and contractility in pigs with focal infarctions

Conference IEEE International Ultrasonics Symposium Ius · December 1, 2012 Four pigs, three with focal infarctions in the apical intraventricular septum (IVS) and/or left ventricular free wall (LVFW), were imaged with an intracardiac echocardiography (ICE) transducer. Custom beam sequences were used to excite the myocardium with ... Full text Cite

Direct in vivo myocardial infarct visualization using 3D ultrasound and passive strain contrast

Conference IEEE International Ultrasonics Symposium Ius · December 1, 2011 An approach for myocardial elastography is presented for infarct visualization. Infarcts are visualized using passive strain in the ventricles induced by atrial contraction. Results are compared against ARFI and delay-enhanced contrast MR. © 2011 IEEE. ... Full text Cite

Parametric pressure-volume analysis and acoustic radiation force impulse imaging of left ventricular function

Conference Proceedings IEEE Ultrasonics Symposium · December 1, 2010 Extensive research has been devoted to the quantification of left ventricular (LV) function via an elasticity metric known as elastance. Similar to a stress-strain relation, yielding stiffness, myocardial elastance is measured from the pressure-volume (PV) ... Full text Cite

Intracranial catheter for integrated 3D ultrasound imaging & hyperthermia: Feasibility study

Conference Aip Conference Proceedings · July 21, 2009 In this study, we investigated the feasibility of an intracranial catheter transducer capable of real-time 3D (RT3D) imaging and ultrasound hyperthermia, for application in the visualization and treatment of tumors in the brain. We designed and constructed ... Full text Cite

ARFI imaging of thermal lesions in ex vivo and in vivo soft tissues

Conference Proceedings of the IEEE Ultrasonics Symposium · December 1, 2003 The ability of ARFI imaging to monitor the ablation of soft tissues both ex vivo and in vivo was investigated. Thermal lesions were induced both in freshly excised bovine liver samples and in myocardial tissue of live sheep. While conventional sonography w ... Cite

16-channel neural pre-conditioning device

Conference International IEEE EMBS Conference on Neural Engineering Ner · January 1, 2003 We present the mixed-signal circuit design, layout, implementation techniques, and test data for a 16-channel neural pre-conditioning device that is used to amplify and filter signals acquired from chronically implanted electrodes in an animal's brain. Sch ... Full text Cite

Effects of spike sorting error on information content in multi-neuron recordings

Conference International IEEE EMBS Conference on Neural Engineering Ner · January 1, 2003 In brain-machine interface (BMI) applications, multi-channel recordings are spike sorted before the single-unit spike trains are used in computational analysis to decode the neural response. Nevertheless, questions about the necessity and effectiveness of ... Full text Cite

Estimation of Propagation Speed during Ventricular Fibrillation from frequency-Wavenumber Power Spectra

Conference Computers in Cardiology 1994 · January 1, 1994 Propagation speed during ventricular fibrillation (VF) in pigs was estimated from the frequency-wavenumber power spectrum of epicardial mapping data. Data from a 22 x 23 array of epicardial electrodes were analyzed to obtain power as a function of wavenumb ... Full text Cite

A method for determining surface electrode location and boundary shape using impedance measurements

Conference Proceedings of the Annual International Conference of the IEEE Engineering in Medicine and Biology Society EMBS · January 1, 1992 We have developed an algorithm to determine the boundary shape of a homogeneous volume conductor in cases where the surface can be defined by the location of electrodes. The algorithm adjusts the positions of electrodes in space to provide the best fit to ... Full text Cite

A programmable cardiac stimulator

Conference Proceedings Computers in Cardiology Cic 1992 · January 1, 1992 A programmable constant current cardiac stimulator for use in a cardiac electrophysiology research lab has been implemented with a Macintosh II interfaced to voltage to current converters. The Macintosh II was equipped with three boards from National Instr ... Full text Cite