New algorithm for quantifying vascular changes in dynamic contrast-enhanced MRI independent of absolute T1 values

In this work, we present a new method for predicting changes in tumor vascularity using only one flip angle in dynamic contrast-enhanced (DCE) imaging. The usual DCE approach finds the tissue initial T, value T-1(0) prior to injection of a contrast agent. We propose finding changes in the tissue contrast agent uptake characteristics pre- and postdrug treatment by fixing T-1(0). Using both simulations and imaging pre- and postadministration of caffeine, we find that the relative change (NR50) in the median of the cumulative distribution (R50) is almost independent of T1O(). Fixing T-1(0) leads to a concentration curve c(t) more robust to the presence of noise than calculating T-1(0). Consequently, the NR50 for the tumor remains roughly the same as the ideal NR50 when T-1(0) is exactly known. Further, variations in eating habits are shown to create significant changes in the R50 response for both liver and muscle. In conclusion, analyzing data with fixed T-1(0) leads to a more stable measure of changes in NR50 and does not require knowledge of T-1(0). Both caffeine and eating introduce major changes in blood flow that can significantly modify the NR50 and lead to incorrect conclusions regarding drug treatment.