| Artifacts in T1 rho-weighted imaging: compensation for B(1) and B(0) field imperfections. | |
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MedLine Citation:
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PMID: 17291799 Owner: NLM Status: MEDLINE |
Abstract/OtherAbstract:
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The origin of spin locking image artifacts in the presence of B(0) and B(1) magnetic field imperfections is shown theoretically using the Bloch equations and experimentally at low (omega(1) << Delta omega(0)), intermediate (omega(1) approximately Delta omega(0)) and high (omega(1) >> Delta omega(0)) spin locking field strengths. At low spin locking fields, the magnetization is shown to oscillate about an effective field in the rotating frame causing signature banding artifacts in the image. At high spin lock fields, the effect of the resonance offset Deltao mega(0) is quenched, but imperfections in the flip angle cause oscillations about the omega(1) field. A new pulse sequence is presented that consists of an integrated spin echo and spin lock experiment followed by magnetization storage along the -z-axis. It is shown that this sequence almost entirely eliminates banding artifacts from both types of field inhomogeneities at all spin locking field strengths. The sequence was used to obtain artifact free images of agarose in inhomogeneous B(0) and B(1) fields, off-resonance spins in fat and in vivo human brain images at 3 T. The new pulse sequence can be used to probe very low frequency (0-400 Hz) dynamic and static interactions in tissues without contaminating B(0) and B(1) field artifacts. |
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Authors:
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Walter R T Witschey; Arijitt Borthakur; Mark A Elliott; Eric Mellon; Sampreet Niyogi; Daniel J Wallman; Chenyang Wang; Ravinder Reddy |
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Publication Detail:
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Type: Evaluation Studies; Journal Article; Research Support, N.I.H., Extramural Date: 2007-01-26 |
Journal Detail:
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Title: Journal of magnetic resonance (San Diego, Calif. : 1997) Volume: 186 ISSN: 1090-7807 ISO Abbreviation: J. Magn. Reson. Publication Date: 2007 May |
Date Detail:
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Created Date: 2007-04-30 Completed Date: 2007-06-27 Revised Date: 2009-11-18 |
Medline Journal Info:
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Nlm Unique ID: 9707935 Medline TA: J Magn Reson Country: United States |
Other Details:
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Languages: eng Pagination: 75-85 Citation Subset: IM |
Affiliation:
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Graduate Group in Biochemistry and Molecular Biophysics and MMRRCC, University of Pennsylvania, B1 Stellar-Chance Laboratories, 422 Curie Boulevard, Philadelphia, PA 19104-6100, USA. witschey@med.upenn.edu |
Export Citation:
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| MeSH Terms | |
Descriptor/Qualifier:
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Algorithms* Artifacts* Brain / anatomy & histology* Humans Image Enhancement / methods* Image Interpretation, Computer-Assisted / methods* Magnetic Resonance Imaging / methods* Reproducibility of Results Sensitivity and Specificity |
| Grant Support | |
ID/Acronym/Agency:
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P41 RR002305-22/RR/NCRR NIH HHS; R01 AR045242-06/AR/NIAMS NIH HHS; R01AR045404/AR/NIAMS NIH HHS; R01AR051041/AR/NIAMS NIH HHS; RR02305/RR/NCRR NIH HHS |
| Comments/Corrections | |
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine
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