Showing papers by "Daniel K. Sodickson published in 2007"
Patent•
21 Feb 2007TL;DR: In this paper, a method of obtaining magnetic resonance (MR) and radio frequency impedance mapping (RFIM) data from a region of an object arranged proximate a plurality of radio-frequency (RF) coils (120a, 120b) is provided.
Abstract: In one aspect, a method of obtaining magnetic resonance (MR) and radio- frequency impedance mapping (RFIM) data from a region of an object (190) arranged proximate a plurality of radio-frequency (RF) coils (120a, 120b) is provided. The method comprises detecting nuclear magnetic resonance (WMR) signals emitted from the region to form, at least in part, first MR data, obtaining at least one impedance measurement from the plurality of RF coils to form, at least in part, first RFIM data, and computing a first RFIM map indicating a spatial distribution in the region of at least one dielectric property, the first RFIM map computed based, at least in part, on the first RFIM data and the first MR data.
45 citations
TL;DR: The most immediate problems of imaging at ultrahigh field strength are not unfamiliar, as many of them are still pressing issues at 3T: radiofrequency coils, B1 homogeneity, specific absorption rate, safety, B0 field homogeneity and chemical shift as mentioned in this paper.
19 citations
15 Mar 2007
TL;DR: This article discusses image-domain subencoding techniques, the history of parallel MRI, and a recipe for Practical Parallel Imaging.
Abstract: The sections in this article are
1
Introduction
2
The History of Parallel MRI
3
Smash Imaging
4
Image-Domain Subencoding Techniques
5
A Recipe for Practical Parallel Imaging
6
The Future of Parallel MRI
7
Biographical Sketch
Related Articles
12 citations
TL;DR: The Society for Cardiovascular Magnetic Resonance (SCMR) 2007 meeting was held from February 2 to February 4 in Rome, Italy as mentioned in this paper, where the meeting was jointly with the Working Group for CMR of the European Society of Medicine.
7 citations
01 Jan 2007
TL;DR: In this paper, the authors used the optimal weighting factors to find the excitation patterns f (n) (r) that result in minimum average SAR in the case of EPI-trajectory small tip-angle parallel excitations.
Abstract: (n) (r), the periodic excitation patterns, by a Fourier transform, using Parseval’s theorem, ξ can be expressed as a quadratic form in terms of fp [5]: ξ = 1/P (f p H Φf p ) 1 P . Φ is a positive definite covariance matrix. In accelerated parallel excitation, the aliased single-coil excitation patterns are linearly combined such that the aliasing lobes cancel out and the central lobe generates the desired profile. This condition represents the constraint for the design of pulses that minimize power deposition in the subject. We also know that the electromagnetic field inside the subject can be expressed as a sum of weighted basis functions that are multipole expansion solutions of source-free Maxwell’s equations [4]. Therefore, in order to calculate the ultimate intrinsic SAR, we have to solve a constrained optimization of the weighting factors, minimizing ξ under the design constraint. For this work, a solution was calculated in the case of EPI-trajectory small tip-angle parallel excitations following a method outlined by Zhu [5]. We used the optimal weighting factors to find the excitation patterns f (n) (r) that result in minimum average SAR. This was carried out one set of aliased pixels (x,y) at a time: f p =Φ −1 C x,y H (C x,y Φ −1 C x,y H ) −1 µ x,y ,
4 citations