| Concomitant gradient terms in phase contrast MR: analysis and correction. | |
| | |
MedLine Citation:
|
PMID: 9469714 Owner: NLM Status: MEDLINE |
Abstract/OtherAbstract:
|
Whenever a linear gradient is activated, concomitant magnetic fields with non-linear spatial dependence result. This is a consequence of Maxwell's equations, i.e., within the imaging volume the magnetic field must have zero divergence, and has negligible curl. The concomitant, or Maxwell field has been described in the MRI literature for over 10 years. In this paper, we theoretically and experimentally show the existence of two additional lowest-order terms in the concomitant field, which we call cross-terms. The concomitant gradient cross-terms only arise when the longitudinal gradient Gz is simultaneously active with a transverse gradient (Gx or Gy). The effect of all of the concomitant gradient terms on phase contrast imaging is examined in detail. Several methods for reducing or eliminating phase errors arising from the concomitant magnetic field are described. The feasibility of a joint pulse sequence-reconstruction method, which requires no increase in minimum TE, is demonstrated. Since the lowest-order terms of the concomitant field are proportional to G2/B0, the importance of concomitant gradient terms is expected to increase given the current interest in systems with stronger gradients and/or weaker main magnetic fields. |
| | |
Authors:
|
M A Bernstein; X J Zhou; J A Polzin; K F King; A Ganin; N J Pelc; G H Glover |
Related Documents
:
|
19963234 - Photocatalytic magnetic separable beads for chromium (vi) reduction. 16808074 - A review of magnetic resonance imaging compatible manipulators in surgery. 15725124 - Third-order aberration theory of wien filters for monochromators and aberration correct... 15133504 - Substantial reduction of critical current for magnetization switching in an exchange-bi... 17693204 - Advances in respiratory imaging. 19936884 - A case of primary psoas abscess presenting as buttock abscess. |
Publication Detail:
|
Type: Journal Article |
Journal Detail:
|
Title: Magnetic resonance in medicine : official journal of the Society of Magnetic Resonance in Medicine / Society of Magnetic Resonance in Medicine Volume: 39 ISSN: 0740-3194 ISO Abbreviation: Magn Reson Med Publication Date: 1998 Feb |
Date Detail:
|
Created Date: 1998-03-24 Completed Date: 1998-03-24 Revised Date: 2004-11-17 |
Medline Journal Info:
|
Nlm Unique ID: 8505245 Medline TA: Magn Reson Med Country: UNITED STATES |
Other Details:
|
Languages: eng Pagination: 300-8 Citation Subset: IM |
Affiliation:
|
GE Medical Systems, Waukesha, Wisconsin 53188, USA. |
Export Citation:
|
APA/MLA Format Download EndNote Download BibTex |
| MeSH Terms | |
Descriptor/Qualifier:
|
Artifacts Feasibility Studies Humans Image Processing, Computer-Assisted* Magnetic Resonance Angiography / methods* Phantoms, Imaging |
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine
Previous Document: Comparison of four magnetization preparation schemes to improve blood-wall contrast in cine short-ax...
Next Document: Localized proton NMR spectroscopy in the striatum of patients with idiopathic spasmodic torticollis.