Comparative study into the robustness of compartmental modeling and model-free analysis in DCE-MRI studies

Abstract

Purpose

To evaluate and compare the reproducibility of the preferred phenomenological parameter IAUC₆₀ (initial area under the time-concentration curve [IAUC] defined over the first 60 seconds postenhancement) with the preferred modeling parameter (K^trans), as derived using two simple models, in abdominal and cerebral data collected in typical Phase I clinical trial conditions.

Materials and Methods

Dynamic contrast enhanced MRI (DCE-MRI) time series were acquired at two imaging centers from a group of patients with abdominal tumors and a group with gliomas. At both imaging centers, precontrast T₁ was calculated using a variable flip angle three-dimensional spoiled gradient echo acquisition that was used to quantify tissue contrast agent concentration, allowing voxelwise definition of summary DCE-MRI parameters.

Results

A comparison of reproducibility showed that there was no statistically significant difference in reproducibility between IAUC₆₀ and K^trans, although there was a trend towards better reproducibility for K^trans (P = 0.0782). The 95% confidence intervals (CIs) for individual changes showed that for IAUC₆₀ and K^trans, changes in excess of 47% and 31%, respectively, are outside the range of normal variability.

Conclusion

Although modeling is more complex and more computationally intensive than an IAUC parameterization, our data suggest this approach to be preferable to a model-free approach since it provides greater physiological insight without a reduction in statistical power for Phase I/II clinical drug trials. J. Magn. Reson. Imaging 2006. © 2006 Wiley-Liss, Inc.