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Mathematical optimization of contrast concentration for t 1 ‐weighted spoiled gradient echo imaging
Author(s) -
Reeder Scott B.,
Smith Matthew R.,
Hernando Diego
Publication year - 2016
Publication title -
magnetic resonance in medicine
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.696
H-Index - 225
eISSN - 1522-2594
pISSN - 0740-3194
DOI - 10.1002/mrm.25744
Subject(s) - flip angle , contrast (vision) , gadolinium , signal (programming language) , nuclear magnetic resonance , pulse sequence , transverse plane , gradient echo , pulse (music) , offset (computer science) , materials science , biomedical engineering , magnetic resonance imaging , biological system , chemistry , computer science , physics , optics , medicine , radiology , detector , metallurgy , programming language , biology
Purpose To develop and validate closed form mathematical expressions that predict the optimal contrast agent concentration for the maximum T 1 ‐weighted spoiled gradient echo (SGRE) signal. Theory and Methods Gadolinium and iron‐based contrast agents can have significant transverse relaxivity that leads to signal dropout with increasing contrast agent concentration. A mathematical expression for the “optimal” contrast agent concentration where recovery of longitudinal magnetization is offset by increasing transverse signal decay was derived. Expressions for the maximum possible SGRE signal were also derived. Three phantoms were constructed, each with varying concentrations of one of the following three agents: gadoteridol, gadobenate dimeglumine, and ferumoxytol. After measuring the longitudinal and transverse relaxivity of the three agents, the SGRE signal was measured in the phantoms over a wide range of flip angles and echo times. Results Excellent qualitative agreement between the SGRE signal behavior, optimal concentration, and optimal flip angle were observed between experimental measurements and theoretical predictions. Conclusion This work provides validated mathematical expressions for contrast enhanced T 1 ‐weighted SGRE imaging and may provide guidance for contrast dosing and injection protocols, as well as for novel pulse sequence design. Magn Reson Med 75:1556–1564, 2016. © 2015 Wiley Periodicals, Inc.