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Search Publications by: Stephen E. Russek (Fed)

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Displaying 1 - 25 of 170

Magnetic Resonance Imaging Biomarker Calibration Service: NMR Measurement of Isotropic Water Diffusion Coefficient

March 30, 2023
Stephen E. Russek, Katy Keenan, Karl Stupic, Nikki Rentz, Michael Boss, Kevin J. Coakley, Amanda Koepke, Cassandra Stoffer
This document describes a calibration service to measure the water diffusion coefficient, or diffusivity, in reference materials and tissue mimics using nuclear magnetic resonance (NMR) techniques. This calibration is restricted to materials which exhibit

Imaging of Magnetic Excitations in Nanostructures with Microwave Near-Field Microscopy

November 25, 2021
Samuel Berweger, Robert Tyrrell-Ead, Houchen Chang, Mingzhong Wu, Hong Tang, Hans Nembach, Karl Stupic, Stephen E. Russek, Thomas Mitchell (Mitch) Wallis, Pavel Kabos
We present images of spin-wave excitations in a patterned yttrium iron garnet (YIG) thin film obtained by use of near-field microwave microscopy, which can achieve spatial resolution as high as 50 nm. Visualization of magnetic excitations is an enticing

Characterization of 3-Dimensional Printing and Casting Materials for use in Computed Tomography and X-ray Imaging Phantoms

September 15, 2020
Bryan E. Yunker, Andrew Holmgren, Karl Stupic, J. L. Wagner, S Huddle, R Shandas, R. F. Weir, Katy Keenan, Edward Garboczi, Stephen E. Russek
Imaging phantoms are used to calibrate and validate the performance of medical computed tomography (CT) systems. Many new materials developed for three-dimensional (3D) printing processes may be useful in the direct printing or casting of biomimetic and

Characterization of 3-Dimensional Printing and Casting Materials for use in Magnetic Resonance Imaging Phantoms at 3 T

September 15, 2020
Bryan E. Yunker, Karl Stupic, J. L. Wagner, S Huddle, R Shandas, R. F. Weir, Stephen E. Russek, Katy Keenan
Imaging phantoms are used to calibrate and validate the performance of magnetic resonance imaging (MRI) systems. Many new materials have been developed for additive manufacturing (three-dimensional [3D] printing) processes that may be useful in the direct

Electromagnetics for Quantitative Magnetic Resonance Imaging

July 20, 2020
Stephen E. Russek, Karl F. Stupic, Joshua R. Biller, Michael A. Boss, Kathryn E. Keenan, Elizabeth Mirowski
Magnetic Resonance Imaging (MRI) is based on radio frequency (RF) interrogation of the human body at frequencies between 40 MHz to 300 MHz. An RF transmitter excites proton spin precession and then, in a manner analogous to an RF ID tag, the proton’s

Synaptic weighting in single flux quantum neuromorphic computing

January 22, 2020
Michael L. Schneider, Christine A. Donnelly, Ian W. Haygood, Alex Wynn, Stephen E. Russek, Manuel C. Castellanos Beltran, Paul D. Dresselhaus, Peter F. Hopkins, Matthew R. Pufall, William H. Rippard
Josephson junctions act as a natural spiking neuron-like device for neuromorphic computing. By leveraging the advances recently demonstrated in digital single flux quantum (SFQ) circuits and using recently demonstrated magnetic Josephson junction (MJJ)

Progress Towards Standards for Quantitative MRI (qMRI) and Outstanding Needs

January 24, 2019
Kathryn E. Keenan, Joshua R. Biller, Michael A. Boss, Adele P. Peskin, Karl F. Stupic, Stephen E. Russek, Jana Delfino, Mark Does, Jeffrey L. Evelhoch, Mark Griswold, Jeffrey Gunter, R Scott Hinks, Stuart Hoffman, Geena Kim, Riccardo Lattanzi, Xiaojuan Li, Luca Marinelli, Pratik Mukherjee, Robert J. Nordstrom, Elena Perez, Berkman Sahiner, Natalie J. Serkova, Amita Shukla-Dave, Michael Steckner, Lisa J. Wilmes, Holden Wu, Huiming Zhang, Edward F. Jackson, Daniel Sullivan
The National Institute of Standards and Technology (NIST) MRI Standards project held a one-day workshop on August 4, 2017 on campus in Boulder, CO. The goal of the workshop was to evaluate the advances in quantitative MRI (qMRI) since the last NIST

Energy efficient single flux quantum based neuromorphic computing

November 8, 2018
Michael Schneider, Christine A. Donnelly, Stephen E. Russek, Burm Baek, Matthew Pufall, Pete Hopkins, William Rippard
Many neuromorphic hardware technologies are being explored for their potential to increase the efficiency of computing certain problems, and thus facilitate machine learning with greater energy efficiency and or with more complexity. Among the technologies

High-speed low-power neuromorphic systems based on magnetic Josephson junctions

October 25, 2018
Michael Schneider, Christine A. Donnelly, Stephen E. Russek
Josephson junctions and single flux quantum (SFQ) circuits form a natural neuromorphic technology with SFQ pulses and superconducting transmission lines simulating action potentials and axons, respectively. Josephson junctions consist of superconducting

Nano-Sized Ferrite Particles for Magnetic Resonance Imaging Thermometry

September 8, 2018
Janusz H. Hankiewicz, J A. Stoll, John Stroud, J Davidson, K L. Livesey, K Tvrdy, Alexana Roshko, Stephen E. Russek, Karl Stupic, P Bilski, Robert E. Camley
Recently, we reported the use of magnetic particles as temperature indicators in magnetic resonance imaging thermometry (tMRI). In this method, the brightness of the MR image changes with temperature due to a temperature-dependent magnetic field

Large T1 contrast enhancement using superparamagnetic nanoparticles in ultra-low field MRI

June 5, 2018
Xiaolu Yin, Stephen E. Russek, Gary Zabow, Fan Sun, Jeotikanta Mohapatra, Kathryn E. Keenan, Michael A. Boss, Hao Zeng, Sy-Hwang Liou, John M. Moreland
Superparamagnetic iron oxide nanoparticles (SPIONs) are widely investigated and utilized as magnetic resonance imaging (MRI) contrast and therapy agents due to their large magnetic moments. Local field inhomogeneities caused by these high magnetic moments

Magnetic Resonance Imaging Biomarker Calibration Service: Proton Spin Relaxation Times

May 3, 2018
Michael A. Boss, Andrew M. Dienstfrey, Zydrunas Gimbutas, Kathryn E. Keenan, Jolene D. Splett, Karl F. Stupic, Stephen E. Russek
This document describes the calibration service to measure proton spin relaxation times, T1 and T2, of materials used in phantoms (calibration artifacts) to verify the accuracy of MRI-based quantitative measurements. Proton spin relaxation times are used

Ultralow power artificial synapses using nanotextured magnetic Josephson junctions

January 28, 2018
Michael L. Schneider, Christine A. Donnelly, Stephen E. Russek, Burm Baek, Matthew R. Pufall, Peter F. Hopkins, Paul D. Dresselhaus, Samuel P. Benz, William H. Rippard
Neuromorphic computing is a promising avenue to dramatically improve the efficiency of certain computational tasks, such as perception and decision making. Neuromorphic systems are currently being developed for critical applications ranging from self

MRI Birdcage RF Coil Resonance with Uncertainty and Relative Error Convergence Rates

October 4, 2017
Jeffrey T. Fong, Nathanael A. Heckert, James J. Filliben, Pedro V. Marcal, Robert Rainsberger, Karl F. Stupic, Stephen E. Russek
In a magnetic resonance imaging (MRI) system, it is necessary to excite the nuclei of a patient into coherent precession for imaging. This requires a coupling between the nuclei and a source of radio frequency (RF) power using a transmitter. To receive a

Quantitative Magnetic Resonance Imaging Phantoms: A Review and the Need for a System Phantom

October 4, 2017
Kathryn E. Keenan, Maureen Ainslie, Alexander J. Barker, Michael A. Boss, Kim M. Cecil, Cecil Charles, Thomas L. Chenevert, Laurence Clarke, Jeffrey L. Evelhoch, Paul Finn, Guoying Liu, Stephen E. Russek, Karl F. Stupic, Joshua D. Trzasko, Chun Yuan, Jie Zheng
The MRI community is using quantitative mapping techniques to complement qualitative imaging. For quantitative imaging to reach its full potential, it is necessary to analyze measurements across systems and longitudinally. Clinical use of quantitative

Accuracy, repeatability and interplatform reproducibility measurements of T 1 quantification methods used for DCE-MRI: results from a multicenter phantom study.

August 16, 2017
Octavia Bane, Stefanie J. Hectors, Mathilde Wagner, Lori L. Arlinghaus, Madhava P. Aryal, Yue Cao, Thomas L. Chenevert, Fiona Fennessy, Wei Huang, Nola M. Hylton, Jayashree Kalpathy-Cramer, Katy Keenan, Dariya I. Malyarenko, Robert V. Mulkern, David C. Newitt, Stephen E. Russek, Karl Stupic, Michael A. Boss
Purpose: To determine the in vitro accuracy, test-retest repeatability, and interplatform reproducibility of T 1 quantification protocols used for dynamic contrast-enhanced MRI at 1.5 and 3 T. Methods: A T 1 phantom with 14 samples was imaged at eight

Accuracy of magnetic resonance based susceptibility measurements

February 6, 2017
Hannah E. Erdevig, Stephen E. Russek, Slavka Carnicka, Karl F. Stupic, Kathryn E. Keenan
Magnetic Resonance Imaging (MRI) is increasingly used to map the magnetic susceptibility of tissue to identify cerebral microbleeds associated with traumatic brain injury and pathological iron deposits associated with neurodegenerative diseases such as