Open AccessThe reciprocal linear QUEST analysis method facilitates the measurements of chemical exchange rates with CEST MRI
Author(s) -
Randtke Edward A.,
Chen Liu Qi,
Pagel Mark D.
Publication year - 2014
Publication title -
contrast media & molecular imaging
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.714
H-Index - 50
eISSN - 1555-4317
pISSN - 1555-4309
DOI - 10.1002/cmmi.1566
Subject(s) - saturation (graph theory) , nuclear magnetic resonance , magnetic resonance imaging , chemistry , materials science , physics , mathematics , radiology , medicine , combinatorics
Magnetic resonance imaging (MRI) contrast media that are detected via chemical exchange saturation transfer (CEST) often require an accurate estimation of their chemical exchange rate, k ex . A variety of analysis methods have been proposed to estimate k ex , including the nonlinear QUEST analysis method that evaluates the CEST amplitude as a function of saturation time. We have derived a linear version of QUEST, termed the Reciprocal Linear QUEST (RL‐QUEST) method. Our simulations and experimental results show that RL‐QUEST performs as well as QUEST, while providing a more simplistic fitting procedure. Although CEST results should be acquired with saturation power that has a nutation rate that is faster than k ex of the CEST agent, an exact determination of the saturation power is not required to accurately estimate k ex with RL‐QUEST. This new analysis method requires a determination of the CEST agent's concentration, which is straightforward for the analysis of CEST agents in chemical solutions, but may be a limitation during in vivo CEST MRI studies. Based on the results of this study and previous studies, we provide recommendations for the linear analysis method that should be employed for each type of CEST MRI study. Copyright © 2014 John Wiley & Sons, Ltd.