Comparison of a reference region model with direct measurement of an AIF in the analysis of DCE-MRI data

Models have been developed for analyzing dynamic contrast-enhanced (DCE)-MRI data that do not require measurements of the arterial input function (AIF). In this study, experimental results obtained from a reference region (FIR) analysis are compared with results of an AIF analysis in the same set of five animals (four imaged twice, yielding nine data sets), returning estimates of the volume transfer constant (K-trans) and the extravascular extracellular volume fraction (v,). Student's t-test values for comparisons of K-trans and v(e) between the two models were 0.14 (P = 0.88) and 0.85 (P > 0.4), respectively (where the high P-values indicate no significant difference between values derived from the two models); Linear regression analysis indicated there was a correlation between K-trans extracted by the two methods: r(2) = 0.80, P = 0.001 (where the low P value indicates a significant linear correlation). For v. there was no such correlation (r(2) = 0.02). The mean (absolute) percent difference between the models was 22.0% for K-trans and 28.1% for v(e). However, the FIR parameter values were much less precise than the AIF method. The mean SDs for K-trans and v(e) for the RR analysis were 0.024 min(-1) and 0.06, respectively, vs. 0.002 min(-1) and 0.03 for AIF analysis. Magn Reson Med 57:353-361, 2007. (c) 2007 Wiley-Liss, Inc.