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Incorporating the effects of transcytolemmal water exchange in a reference region model for DCE‐MRI analysis: Theory, simulations, and experimental results
Author(s) -
Yankeelov Thomas E.,
Luci Jeffrey J.,
DeBusk Laura M.,
Lin P. Charles,
Gore John C.
Publication year - 2008
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.21449
Subject(s) - voxel , contrast (vision) , volume (thermodynamics) , nuclear magnetic resonance , mathematics , computer science , physics , thermodynamics , artificial intelligence
Models have been developed for the analysis of dynamic contrast‐enhanced MRI (DCE‐MRI) data that do not require direct measurements of the arterial input function; such methods are referred to as reference region models. These models typically return estimates of the volume transfer constant ( K trans ) and the extravascular extracellular volume fraction ( v e ). To date such models have assumed a linear relationship between the measured R 1 (≡1/ T 1 ) and the concentration of contrast agent, a transformation referred to as the fast exchange limit, but this assumption is not valid for all concentrations of an agent. A theory for DCE‐MRI reference region models which accounts for water exchange is presented, evaluated in simulations, and applied in tumor‐bearing mice. Using reasonable parameter values, simulations show that the assumption of fast exchange can underestimate K trans and v e by up to 82% and 46%, respectively. By analyzing a large region of interest and a single voxel the new model can return parameters within approximately ±10% and ±25%, respectively, of their true values. Analysis of experimental data shows that the new approach returns K trans and v e values that are up to 90% and 73%, respectively, greater than conventional fast exchange analyses. Magn Reson Med 59:326–335, 2008. © 2008 Wiley‐Liss, Inc.