Premium
Eddy current correction in volume‐localized MR spectroscopy
Author(s) -
Lin Chen,
Wendt Richard E.,
Evans Harlan J.,
Rowe Roger M.,
Hedrick Thomas D.,
LeBlanc Adrian D.
Publication year - 1994
Publication title -
journal of magnetic resonance imaging
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.563
H-Index - 160
eISSN - 1522-2586
pISSN - 1053-1807
DOI - 10.1002/jmri.1880040614
Subject(s) - eddy current , signal (programming language) , weighting , distortion (music) , nuclear magnetic resonance , physics , relaxation (psychology) , interference (communication) , acoustics , volume (thermodynamics) , current (fluid) , computer science , telecommunications , psychology , amplifier , social psychology , channel (broadcasting) , optoelectronics , cmos , quantum mechanics , thermodynamics , programming language
The quality of volume‐localized magnetic resonance spectroscopy is affected by eddy currents caused by gradient switching. Eddy currents can be reduced with improved gradient systems; however, it has been suggested that the distortion due to eddy currents can be compensated for during postprocessing with a single‐frequency reference signal. The authors propose modifying current techniques for acquiring the single‐frequency reference signal by using relaxation weighting to reduce interference from components that cannot be eliminated by digital filtering alone. Additional sequences with T1 or T2 weighting for reference signal acquisition are shown to have the same eddy current characteristics as the original signal without relaxation weighting. The authors also studied a new eddy current correction method that does not require a single‐frequency reference signal. This method uses two free induction decays (FIDs) collected from the same volume with two sequences with opposite gradients. Phase errors caused by eddy currents are opposite in these two FIDs and can be canceled completely by combining the FIDs. These methods were tested in a phantom. Eddy current distortions were corrected, allowing quantitative measurement of structures such as the –CHCH– component, which is otherwise undetectable.