Concepts in Magnetic Resonance Part B: Magnetic Resonance Engineering This is an RSS file. You can use it to subscribe to this data in your favourite RSS reader or to display this data on your own website or blog.

Maximally spaced projection sequencing in electron paramagnetic resonance imaging
ABSTRACT Electron paramagnetic resonance imaging (EPRI) provides 3D images of absolute oxygen concentration (pO2) in vivo with excellent spatial and pO2 resolution. When investigating such physiologic parameters in living animals, the situation is inherently dynamic. Improvements in temporal resolution and experimental versatility are necessary to properly study such a system. Uniformly distributed projections result in efficient use of data for image reconstruction. This has dictated current methods such as equal‐solid‐angle (ESA) spacing of projections. However, acquisition sequencing must still be optimized to achie...
Source: Concepts in Magnetic Resonance Part B: Magnetic Resonance Engineering - October 1, 2014 Category: Radiology Authors: Gage Redler, Boris Epel, Howard J. Halpern Tags: Research Article Source Type: research

A novel acoustically quiet coil for neonatal MRI system
ABSTRACT Magnetic resonance imaging (MRI) acoustic exposure has the potential to elicit physiological distress and impact development in preterm and term infants. To mitigate this risk, a novel acoustically quiet coil was developed to reduce the sound pressure level experienced by neonates during MR procedures. The new coil has a conventional high‐pass birdcage radio frequency design, but is built on a framework of sound abating material. We evaluated the acoustic and MR imaging performance of the quiet coil and a conventional body coil on two small footprint neonatal intensive care unit MRI systems. Sound pressure level...
Source: Concepts in Magnetic Resonance Part B: Magnetic Resonance Engineering - October 1, 2014 Category: Radiology Authors: Christopher M. Ireland, Randy O. Giaquinto, Wolfgang Loew, Jean A. Tkach, Ronald G. Pratt, Beth M. Kline‐Fath, Stephanie L. Merhar, Charles L. Dumoulin Tags: Research Article Source Type: research

Acoustic analysis for a split MRI system using FE method
ABSTRACT In some MRI‐LINAC (Magnetic Resonance Imaging and Linear Accelerator) hybrid systems, the MRI scanner is split into two parts to form a central gap for the accommodation of the patient or a LINAC. Little is known about the acoustic characteristics of the split gradient coil structure needed for this system; however, it is believed to be very different from its typical configurations. It is important to develop dedicated numerical methods for the characterization of the unique acoustic properties, to provide engineering solutions for the noise attenuation for such a new system. In this article, we modeled the aco...
Source: Concepts in Magnetic Resonance Part B: Magnetic Resonance Engineering - October 1, 2014 Category: Radiology Authors: Yaohui Wang, Feng Liu, Ewald Weber, Fangfang Tang, Jin Jin, Yas Tesiram, Stuart Crozier Tags: Research Article Source Type: research

Approaching ultimate intrinsic SNR in a uniform spherical sample with finite arrays of loop coils
ABSTRACT We investigated to what degree and at what rate the ultimate intrinsic (UI) signal‐to‐noise ratio (SNR) may be approached using finite radiofrequency detector arrays. We used full‐wave electromagnetic field simulations based on dyadic Green's functions to compare the SNR of arrays of loops surrounding a uniform sphere with the ultimate intrinsic SNR (UISNR), for increasing numbers of elements over a range of magnetic field strengths, voxel positions, sphere sizes, and acceleration factors. We evaluated the effect of coil conductor losses and the performance of a variety of distinct geometrical arrangements s...
Source: Concepts in Magnetic Resonance Part B: Magnetic Resonance Engineering - April 1, 2014 Category: Radiology Authors: Manushka V. Vaidya, Daniel K. Sodickson, Riccardo Lattanzi Tags: Research Article Source Type: research

Issue Information
(Source: Concepts in Magnetic Resonance Part B: Magnetic Resonance Engineering)
Source: Concepts in Magnetic Resonance Part B: Magnetic Resonance Engineering - April 1, 2014 Category: Radiology Tags: Issue Information Source Type: research

NMR Concepts
(Source: Concepts in Magnetic Resonance Part B: Magnetic Resonance Engineering)
Source: Concepts in Magnetic Resonance Part B: Magnetic Resonance Engineering - February 24, 2014 Category: Radiology Tags: NMR Concepts Source Type: research

Basic Concepts in NMR
(Source: Concepts in Magnetic Resonance Part B: Magnetic Resonance Engineering)
Source: Concepts in Magnetic Resonance Part B: Magnetic Resonance Engineering - February 24, 2014 Category: Radiology Authors: G. Joseph Ray Tags: DVD Review Source Type: research

Analytical expressions for magnetic fields and field gradients of current‐carrying triangles
We present an analytical method for calculating magnetic field gradients generated by arbitrary triangulated surfaces. Our work builds upon the results published by Pissanetzky and Xiang, who presented formulas for calculating the magnetic field of current‐carrying faceted surfaces. We show that the analytical gradient expressions can be computed considerably faster than finite field value differences. We also find that the aforementioned published expressions for the magnetic field can be simplified and optimized substantially. Closer inspection of the algorithms, for both field and gradient, reveals a number pathologic...
Source: Concepts in Magnetic Resonance Part B: Magnetic Resonance Engineering - February 24, 2014 Category: Radiology Authors: Peter Forthmann, Thomas Amthor Tags: Research Article Source Type: research

CMOS based Q‐switch for low‐power pulsed14N quadruple resonance
ABSTRACT In order to reduce the recovery time of the nuclear quadrupole resonance probe (which implies the insertion of a dead time between the end of the pulse and the beginning of signal acquisition), several strategies have been proposed in the case of high‐power radio frequency (rf) pulses. In fact, these strategies rely on a common principle, which is to lower, for an appropriate duration, the probe quality factor immediately after the transmit pulse. The quality factor is then restored for the receive period. In the case of a low‐power rf pulses, we propose a very simple circuit that can alleviate the ringing fol...
Source: Concepts in Magnetic Resonance Part B: Magnetic Resonance Engineering - February 24, 2014 Category: Radiology Authors: Sarra Aissani, Laouès Guendouz, Daniel Canet Tags: Research Article Source Type: research

Dependence of NMR noise line shapes on tuning, matching, and transmission line properties
ABSTRACT The tuning and matching conditions of rf circuits, as well as the properties of the transmission lines connecting these to the preamplifier, have direct consequences for NMR probe sensitivity and as for the optimum delivery of rf power to the sample. In addition, tuning/matching conditions influence radiation damping effects, which manifest themselves as fast signal flip‐back and line broadening effects, and can lead to concentration‐dependent frequency shifts. Previous studies have also shown that the appearance of spin‐noise and absorbed circuit noise signals heavily depended on tuning settings. Consequent...
Source: Concepts in Magnetic Resonance Part B: Magnetic Resonance Engineering - February 24, 2014 Category: Radiology Authors: Eli Bendet‐Taicher, Norbert Müller, Alexej Jerschow Tags: Research Article Source Type: research

Issue Information
(Source: Concepts in Magnetic Resonance Part B: Magnetic Resonance Engineering)
Source: Concepts in Magnetic Resonance Part B: Magnetic Resonance Engineering - February 1, 2014 Category: Radiology Tags: Issue Information Source Type: research

NMR Concepts
(Source: Concepts in Magnetic Resonance Part B: Magnetic Resonance Engineering)
Source: Concepts in Magnetic Resonance Part B: Magnetic Resonance Engineering - October 18, 2013 Category: Radiology Tags: NMR Concepts Source Type: research

Basic Concepts in NMR
(Source: Concepts in Magnetic Resonance Part B: Magnetic Resonance Engineering)
Source: Concepts in Magnetic Resonance Part B: Magnetic Resonance Engineering - October 18, 2013 Category: Radiology Authors: G. Joseph Ray Tags: DVD Review Source Type: research

Retrospective 3D Modeling of RF Coils Using a 3D Tracker for EM Simulation
ABSTRACT The 3D geometry of the RF coil in use is often unavailable when the RF coil is a commercial one or the RF coil has been developed through ad hoc modification of the coil shape at the laboratory. Without the coil geometry information, making a 3D model of the RF coil may be necessary to simulate the RF coil performance using a finite difference time domain (FDTD) solver. We used a stylus‐type 3D tracker to measure the 3D positions of the landmarks on the coil wires. From the measured landmark positions, we built 3D models of the coil wires using a 3D design tool. We also carried out FDTD simulation of the RF coil...
Source: Concepts in Magnetic Resonance Part B: Magnetic Resonance Engineering - October 18, 2013 Category: Radiology Authors: Dong Eun Kim, Yong Moon Park, Marlon Perez, Daniel Hernandez, Juhyung Lee, Soo Yeol Leei Tags: Research Article Source Type: research

Development and Characterization of An Unshielded PatLoc Gradient Coil for Human Head Imaging
Abstract A cylindrical head gradient insert for human imaging with non‐linear spatial encoding magnetic fields (SEMs) has been designed, optimized and successfully integrated with a modified 3T clinical MR system. This PatLoc (parallel acquisition technique using localized gradients) SEM coil uses SEMs that resemble second‐order magnetic shim fields, but with much higher amplitude as well as the possibility for rapid switching. This work describes the optimization of a coil design and measurement methods to characterize its SEMs, induced self‐eddy currents and concomitant fields. Magnetic field maps of the SEMs are m...
Source: Concepts in Magnetic Resonance Part B: Magnetic Resonance Engineering - October 18, 2013 Category: Radiology Authors: Anna Welz, Chris Cocosco, Andrew Dewdney, Daniel Gallichan, Feng Jia, Heinrich Lehr, Zhenyu Liu, Hans Post, Hartmut Schmidt, Gerrit Schultz, Frederik Testud, Hans Weber, Walter Witschey, Jan Korvink, Jürgen Hennig, Maxim Zaitsev Tags: Research Article Source Type: research