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6. MRI of Pulmonary Ventilation

Author

Wild, Jim M., Hersman, F. William, Patz, Samuel, Muradian, Iga, Hrovat, Mirko I., Hatabu, Hiroto, Butler, James P., Schreiber, Wolfgang G., Dietrich, Olaf, and Kauczor, Hans-Ulrich, editor

Published
2009
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24. Open-Access, Low-Magnetic-Field MRI System for Lung Research

Author

Mair, Ross W, Rosen, Matthew S, Tsai, Leo L, Walsworth, Ronald L, Hrovat, Mirko I, Patz, Samuel, Ruset, Iullian C, and Hersman, F. William

Subjects
Man/System Technology And Life Support
Abstract

An open-access magnetic resonance imaging (MRI) system is being developed for use in research on orientational/gravitational effects on lung physiology and function. The open-access geometry enables study of human subjects in diverse orientations. This system operates at a magnetic flux density, considerably smaller than the flux densities of typical other MRI systems, that can be generated by resistive electromagnet coils (instead of the more-expensive superconducting coils of the other systems). The human subject inhales air containing He-3 or Xe-129 atoms, the nuclear spins of which have been polarized by use of a laser beam to obtain a magnetic resonance that enables high-resolution gas space imaging at the low applied magnetic field. The system includes a bi-planar, constant-current, four-coil electromagnet assembly and associated electronic circuitry to apply a static magnetic field of 6.5 mT throughout the lung volume; planar coils and associated circuitry to apply a pulsed magnetic-field-gradient for each spatial dimension; a single, detachable radio-frequency coil and associated circuitry for inducing and detecting MRI signals; a table for supporting a horizontal subject; and electromagnetic shielding surrounding the electromagnet coils.

Published
2009

26. Imaging localized neuronal activity at fast time scales through biomechanics

Author

Patz, Samuel; https://orcid.org/0000-0002-4500-1918, Fovargue, Daniel, Schregel, Katharina; https://orcid.org/0000-0003-4367-1667, Nazari, Navid; https://orcid.org/0000-0002-7202-5659, Palotai, Miklos; https://orcid.org/0000-0003-0268-6977, Barbone, Paul E; https://orcid.org/0000-0001-6571-7713, Fabry, Ben; https://orcid.org/0000-0003-1737-0465, Hammers, Alexander; https://orcid.org/0000-0001-9530-4848, Holm, Sverre; https://orcid.org/0000-0002-2273-705X, Kozerke, Sebastian; https://orcid.org/0000-0003-3725-8884, Nordsletten, David, Sinkus, Ralph; https://orcid.org/0000-0002-6093-1654, Patz, Samuel; https://orcid.org/0000-0002-4500-1918, Fovargue, Daniel, Schregel, Katharina; https://orcid.org/0000-0003-4367-1667, Nazari, Navid; https://orcid.org/0000-0002-7202-5659, Palotai, Miklos; https://orcid.org/0000-0003-0268-6977, Barbone, Paul E; https://orcid.org/0000-0001-6571-7713, Fabry, Ben; https://orcid.org/0000-0003-1737-0465, Hammers, Alexander; https://orcid.org/0000-0001-9530-4848, Holm, Sverre; https://orcid.org/0000-0002-2273-705X, Kozerke, Sebastian; https://orcid.org/0000-0003-3725-8884, Nordsletten, David, and Sinkus, Ralph; https://orcid.org/0000-0002-6093-1654

Abstract

Mapping neuronal activity noninvasively is a key requirement for in vivo human neuroscience. Traditional functional magnetic resonance (MR) imaging, with a temporal response of seconds, cannot measure high-level cognitive processes evolving in tens of milliseconds. To advance neuroscience, imaging of fast neuronal processes is required. Here, we show in vivo imaging of fast neuronal processes at 100-ms time scales by quantifying brain biomechanics noninvasively with MR elastography. We show brain stiffness changes of ~10% in response to repetitive electric stimulation of a mouse hind paw over two orders of frequency from 0.1 to 10 Hz. We demonstrate in mice that regional patterns of stiffness modulation are synchronous with stimulus switching and evolve with frequency. For very fast stimuli (100 ms), mechanical changes are mainly located in the thalamus, the relay location for afferent cortical input. Our results demonstrate a new methodology for noninvasively tracking brain functional activity at high speed.

Published
2019

28. NMR diffusion simulation based on conditional random walk

Author

Gudbjartsson, Hakon and Patz, Samuel

Subjects
Diagnostic imaging -- Research, Brownian motion -- Research, Random walks (Mathematics) -- Research, Computer simulation -- Methods, Magnetic resonance imaging -- Research, Business, Electronics, Electronics and electrical industries, Health care industry
Abstract

We introduce here a new, very fast, simulation method for free diffusion in a linear magnetic field gradient, which is an extension of the conventional Monte Carlo (MC) method or the convolution method described by Wong et al. In earlier NMR-diffusion simulation methods, such as the finite difference method (FD), the Monte Carlo method, and the deterministic convolution method, the outcome of the calculations depends on the simulation time step. In our method, however, the results are independent of the time step, although, in the convolution method the step size has to be adequate for spins to diffuse to adjacent grid points. By always selecting the largest possible time step the computation time can therefore be reduced. Finally we point out that in simple geometric configurations our simulation algorithm can be used to reduce computation time in the simulation of restricted diffusion.

Published
1995

29. Imaging localized neuronal activity at fast time scales through biomechanics

Author

Patz, Samuel, primary, Fovargue, Daniel, additional, Schregel, Katharina, additional, Nazari, Navid, additional, Palotai, Miklos, additional, Barbone, Paul E., additional, Fabry, Ben, additional, Hammers, Alexander, additional, Holm, Sverre, additional, Kozerke, Sebastian, additional, Nordsletten, David, additional, and Sinkus, Ralph, additional

Published
2019
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30. Cover image, Volume 31 Issue 10

Author

Schregel, Katharina, primary, Nazari, Navid, additional, Nowicki, Michal O., additional, Palotai, Miklos, additional, Lawler, Sean E., additional, Sinkus, Ralph, additional, Barbone, Paul E., additional, and Patz, Samuel, additional

Published
2018
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31. Toward 13C hyperpolarized biomarkers produced by thermal mixing with hyperpolarized 129Xe.

Author

Lisitza, Natalia, Muradian, Iga, Frederick, Eric, Patz, Samuel, Hatabu, Hiroto, and Chekmenev, Eduard Y.

Subjects
BIOMARKERS, POLARIZATION (Nuclear physics), PROTONS, ACETIC acid, PARTICLES (Nuclear physics), GEOMETRIC modeling, VARIATIONAL inequalities (Mathematics)
Abstract

The 13C NMR signal of acetic acid 1-13C-AcH is enhanced by polarization transfer from hyperpolarized 129Xe using a thermal mixing procedure. 1-13C-AcH acid and hyperpolarized 129Xe are mixed as gases to disperse 129Xe in the acetic acid. The mixture is frozen with liquid N2 at 0.5 T. The magnetic field is then momentarily dropped to allow for exchange of spin polarization between 13C and 129Xe. After polarization exchange the magnetic field is raised to its original value and the mixture is thawed, resulting in a solution of polarization enhanced 1-13C-AcH. A 13C nuclear spin polarization enhancement of 10 is observed compared to its thermal polarization at 4.7 T. This polarization enhancement is approximately three orders of magnitude lower than that predicted by theory. The discrepancy is attributed to the formation of either an inhomogeneous solid matrix and/or spin dynamics during polarization transfer. Despite the low polarization enhancement, this is the first report of polarization transfer from 129Xe to 13C nuclear spins achieved by thermal mixing for a proton-containing molecule of biomedical importance. If future work can increase the enhancement, this method will be useful in hyperpolarizing a wide range of 13C enriched compounds important in biomedical and biophysical research. [ABSTRACT FROM AUTHOR]

Published
2009
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36. Characterization of glioblastoma in an orthotopic mouse model with magnetic resonance elastography.

Author

Schregel, Katharina, Nazari, Navid, Nowicki, Michal O., Palotai, Miklos, Lawler, Sean E., Sinkus, Ralph, Barbone, Paul E., and Patz, Samuel

Abstract

Glioblastoma (GBM) is the most common primary brain tumor. It is highly malignant and has a correspondingly poor prognosis. Diagnosis and monitoring are mainly accomplished with MRI, but remain challenging in some cases. Therefore, complementary methods for tumor detection and characterization would be beneficial. Using magnetic resonance elastography (MRE), we performed a longitudinal study of the biomechanical properties of intracranially implanted GBM in mice and compared the results to histopathology. The biomechanical parameters of viscoelastic modulus, shear wave speed and phase angle were significantly lower in tumors compared with healthy brain tissue and decreased over time with tumor progression. Moreover, some MRE parameters revealed sub‐regions at later tumor stages, which were not easily detectable on anatomical MRI images. Comparison with histopathology showed that softer tumor regions contained necrosis and patches of viable tumor cells. In contrast, areas of densely packed tumor cells and blood vessels identified with histology coincided with higher values of viscoelastic modulus and shear wave speed. Interestingly, the phase angle was independent from these anatomical variations. In summary, MRE depicted longitudinal and morphological changes in GBM and may prove valuable for tumor characterization in patients. [ABSTRACT FROM AUTHOR]

Published
2018
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37. MRI of Pulmonary Ventilation

Author

Wild, Jim M., primary, Hersman, F. William, additional, Patz, Samuel, additional, Muradian, Iga, additional, Hrovat, Mirko I., additional, Hatabu, Hiroto, additional, Butler, James P., additional, Schreiber, Wolfgang G., additional, and Dietrich, Olaf, additional

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39. XeNA: An automated ‘open-source’ 129Xe hyperpolarizer for clinical use

Author

Nikolaou, Panayiotis, primary, Coffey, Aaron M., additional, Walkup, Laura L., additional, Gust, Brogan M., additional, Whiting, Nicholas, additional, Newton, Hayley, additional, Muradyan, Iga, additional, Dabaghyan, Mikayel, additional, Ranta, Kaili, additional, Moroz, Gregory D., additional, Rosen, Matthew S., additional, Patz, Samuel, additional, Barlow, Michael J., additional, Chekmenev, Eduard Y., additional, and Goodson, Boyd M., additional

Published
2014
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40. Near-unity nuclear polarization with an open-source 129 Xe hyperpolarizer for NMR and MRI

Author

Nikolaou, Panayiotis, primary, Coffey, Aaron M., additional, Walkup, Laura L., additional, Gust, Brogan M., additional, Whiting, Nicholas, additional, Newton, Hayley, additional, Barcus, Scott, additional, Muradyan, Iga, additional, Dabaghyan, Mikayel, additional, Moroz, Gregory D., additional, Rosen, Matthew S., additional, Patz, Samuel, additional, Barlow, Michael J., additional, Chekmenev, Eduard Y., additional, and Goodson, Boyd M., additional

Published
2013
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46. Quantitative Assessment of Bronchial Wall Attenuation With Thin-Section CT: An Indicator of Airflow Limitation in Chronic Obstructive Pulmonary Disease

Author

Yamashiro, Tsuneo, primary, Matsuoka, Shin, additional, Estépar, Raúl San José, additional, Dransfield, Mark T., additional, Diaz, Alejandro, additional, Reilly, John J., additional, Patz, Samuel, additional, Murayama, Sadayuki, additional, Silverman, Edwin K., additional, Hatabu, Hiroto, additional, and Washko, George R., additional

Published
2010
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