Semiquantitative analysis of dynamic contrast enhanced MRI in cancer patients: Variability and changes in tumor tissue over time

Abstract

Purpose: To evaluate variability of a simplified method for measuring semiquantitative DCE-MRI parameters in patients with cancer and to explore effects of treatment with a putative anti-angiogenic compound. Materials and Methods: A total of 19 patients enrolled on treatment trials with the putative anti-angiogenic agent SU5416 underwent contrast enhanced examinations, and 11 had a second examination eight weeks post therapy. Contrast media concentration as a function of time was calculated using changes in signal and literature baseline T1 values in normal muscle or liver reference tissue. Semiquantitative DCE-MRI parameters, including the area under the contrast concentration vs. time curve (AUC), were calculated for regions-of-interest in normal liver and muscle, and in tumors. Results: The coefficients of variation for pretherapy parameters in normal tissue were 11% to 37%. No significant changes were detected in normal liver over two months of therapy. In tumors and muscle, a significant decrease in the AUC and maximum contrast concentration was observed. Conclusion: Variability of semiquantitative DCE-MRI parameters utilizing a method based on known T1 values in a reference tissue is low enough to detect changes in tumors during therapy. Use of this method as a pharmacodynamic marker should be further investigated.