Comparison of DCE-MRI parametric mapping using MP2RAGE and variable flip angle T1 mapping.

Quantitative dynamic contrast enhanced magnetic resonance imaging (DCE-MRI) measures the rate of transfer of contrast agent from the vascular space to the tissue space by fitting signal-time data to pharmacokinetic models. However, these models are very sensitive to errors in T mapping. Accurate T mapping is necessary for high quality quantitative DCE-MRI studies. This study compares magnetization prepared rapid (two) gradient echo sequence (MP2RAGE) T-mapping accuracy to the conventional variable flip angle (VFA) approach, and also determines the effect of the new T-mapping method on the K parameter. VFA and MP2RAGE T values were compared to the gold standard inverse recovery (IR) method in phantom over manually drawn ROIs. In vivo, ROIs were manually drawn over prostate and prostatic lesions. Average T values over ROIs were compared and K maps for each method were calculated via the extended Tofts model. VFA-T maps overestimated T values by up to 50% compared to gold standard IR T values in phantom. MP2RAGE differed by up to 9%. MP2RAGE-T and K values were significantly different from VFA values over prostatic lesions (p < 0.05). K was consistently underestimated using VFA compared to MP2RAGE (p < 0.05). MP2RAGE T maps are shown to be more accurate, leading to more reliable pharmacokinetic modeling. This can potentially lead to better lesion characterization and improve clinical outcomes.