New insights into the mechanisms of signal formation in RF-spoiled gradient echo sequences
Abstract
RF spoiling is a well established method to produce T1-weighted images with short repetition time gradient-echo sequences, by eliminating coherent transverse magnetization with appropriate RF phase modulation. This paper presents two novel approaches to describe signal formation in such sequences. Both methods rely on the formulation of RF spoiling as a linear increase of the precession angle between RF pulses, which is an alternative to the commonly used quadratic pulse phase scheme. The first technique demonstrates that a steady state signal can be obtained by integrating over all precession angles within the voxel, in spite of the lack of a genuine steady-state for separate isochromats. This clear mathematical framework allows a straightforward incorporation of offresonance effects and detector phase settings. Moreover, it naturally introduces the need for a large net gradient area per repetition interval. In a second step a modified partition method including RF spoiling is developed to obtain explicit expressions for all signal components. This provides a physical interpretation of the deviations from ideal spoiling behavior in FLASH and echo-shifted sequences. The results of the partition method in the small flip angle regime are compared with numerical simulations based on a Fourier decomposition of magnetization states. Measurements performed with in vitro solutions were in good agreement with numerical simulations at short relaxation times (T1/TR = 32 and T2/TR = 4), larger deviations occurred at long relaxation times (T1/TR =114 and T2/TR = 82).Download Info
If you experience problems downloading a file, check if you have the proper application to view it first. In case of further problems read the IDEAS help page. Note that these files are not on the IDEAS site. Please be patient as the files may be large.Bibliographic Info
Paper provided by ULB -- Universite Libre de Bruxelles in its series Working Papers CEB with number 05-006.RS.Length: 3 p.
Date of creation: 2005
Date of revision:
Publication status: Published by:
Handle: RePEc:sol:wpaper:05-006
Contact details of provider:
Postal: CP114/03, 42 avenue F.D. Roosevelt, 1050 Bruxelles
Phone: +32 (0)2 650.48.64
Fax: +32 (0)2 650.41.88
Email:
Web page: http://difusion.ulb.ac.be
More information through EDIRC
Related research
Keywords: RF Spoiling; signal components.;Find related papers by JEL classification:
- C40 - Mathematical and Quantitative Methods - - Econometric and Statistical Methods: Special Topics - - - General
This paper has been announced in the following NEP Reports:
- NEP-ALL-2006-02-05 (All new papers)
References
No references listed on IDEASYou can help add them by filling out this form.
Citations
Lists
This item is not listed on Wikipedia, on a reading list or among the top items on IDEAS.Statistics
Access and download statisticsCorrections
When requesting a correction, please mention this item's handle: RePEc:sol:wpaper:05-006For technical questions regarding this item, or to correct its authors, title, abstract, bibliographic or download information, contact: (Benoit Pauwels).
If you have authored this item and are not yet registered with RePEc, we encourage you to do it here. This allows to link your profile to this item. It also allows you to accept potential citations to this item that we are uncertain about.
If references are entirely missing, you can add them using this form.
If the full references list an item that is present in RePEc, but the system did not link to it, you can help with this form.
If you know of missing items citing this one, you can help us creating those links by adding the relevant references in the same way as above, for each refering item. If you are a registered author of this item, you may also want to check the "citations" tab in your profile, as there may be some citations waiting for confirmation.
Please note that corrections may take a couple of weeks to filter through the various RePEc services.