Dynamic contrast-enhanced MRI in breast cancer: A comparison between distributed and compartmental tracer kinetic models

Background/objectives: Dynamic Contrast Enhanced-Magnetic Resonance Imaging (DCE-MRI) is widely used in tumordiagnosis, staging and assessment of therapy response for different types of tumors, thanks to its capability to provideimportant functional information about tissue microvasculature. Tracer kinetic models used for estimating microcirculatoryparameters can be broadly categorized as conventional compartmental (CC) or distributed- parameter (DP)models. While DP models seem to be more realistic, CC models (in particular the Tofts and the Brix models) have beenwidely used in clinical investigations over the past two decades. However, to date there is no direct comparison of CC vsDP models on real breast DCE-MRI data; moreover, a direct comparison between Tofts and Brix models, has not yet beenreported on real breast data. Therefore, the purpose of this study was two-fold: on the one hand we analyzed theperformance, on real breast DCE-MRI data, of CC vs DP models in terms of goodness-of-fit metrics; on the other hand wecompared Tofts and Brix models on the basis of real breast DCE-MRI data.Methods: Three models were compared: two CC models (the Tofts and the Brix models) and one DP model (the ATHmodel). We gathered data in two different scenarios: DCE-MRI with high temporal resolution obtained by means of ak-space under-sampling and data sharing method known as Time-resolved angiography With Stochastic Trajectories(TWIST) and DCE-MRI with low temporal resolution obtained by means of the Spoiled Gradient-Echo k-space schemeknown as Fast Low Angle Shot (FLASH). The performances of the three models were evaluated by means of threegoodness-of-fit metrics: the Residual Sum of Squares, the Bayesian Information Criterion and the Akaike InformationCriterion on four breast DCE-MRI examinations.Results: Although not conclusive, the results of this study suggest that the ATH model can achieve better fit in comparisonto the Tofts and Brix models for TWIST data; and that the Brix model can achieve better fit with respect to the Tofts modelfor FLASH data.Conclusion: Given the current typical settings of clinical breast DCE-MRI examinations, there seems not to be a clearadvantage, in terms of goodness-of-fit, of ATH with respect to Tofts and Brix models; moreover, at lower temporalresolution the Brix model can achieve better fit than the Tofts model