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First order correction for T 2 *‐relaxation in determining contrast agent concentration from spoiled gradient echo pulse sequence signal intensity
Author(s) -
De Naeyer Dieter,
Debergh Isabelle,
De Deene Yves,
Ceelen Wim P.,
Segers Patrick,
Verdonck Pascal
Publication year - 2011
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.22681
Subject(s) - pulse sequence , contrast (vision) , nuclear magnetic resonance , echo (communications protocol) , signal (programming language) , gradient echo , intensity (physics) , sequence (biology) , pulse (music) , relaxation (psychology) , materials science , physics , chemistry , optics , magnetic resonance imaging , medicine , computer science , radiology , detector , programming language , computer network , biochemistry
Purpose: To investigate the accuracy of a method neglecting T 2 *‐relaxation, for the conversion of spoiled gradient echo pulse sequence signal intensity to contrast agent (CA) concentration, in dynamic contrast enhanced MRI studies. In addition a new closed form conversion expression is proposed that accounts for a first order approximation of T 2 *‐relaxation. Materials and Methods: The accuracy of both conversion methods is compared theoretically by means of simulations for four pulse sequences from literature. Both methods are tested in vivo against the numerical conversion method for measuring the arterial input function in mice. Results: Simulations show that the T 2 *‐neglecting method underestimates typical tissue CA concentrations (0 mM to 2 mM) up to 6%, while the errors for arterial concentrations (0 mM to 10 mM) range up to 43%. The results from our first order method are numerically indistinguishable from the simulation input values in tumor tissue, while for arterial concentrations the error is reduced up to a factor 10. In vivo, peak Gd‐DOTA concentration is underestimated up to 14% with the T 2 *‐neglecting method and up to 0.9% with our first order method. Conclusion: Our conversion method reduces the underestimation of CA concentration severely in a broad physiological concentration range and is easy to perform in any clinical setting. J. Magn. Reson. Imaging 2011;. © 2011 Wiley‐Liss, Inc.