Dynamic contrast-enhanced magnetic resonance imaging of human melanoma xenografts with necrotic regions

Abstract

Purpose: To investigate whether high-resolution images of necrotic regions in tumors can be derived from gadopentetate dimeglumine (Gd-DTPA)-based dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) series. Materials and Methods: E-13 human melanoma xenografts were used as preclinical models of human cancer. DCE-MRI was performed at a voxel size of 0.23 X 0.47 X 2.0 mm 3 with the use of spoiled gradient recalled sequences. Tumor images of E·F (E is the initial extraction fraction of Gd-DTPA and F is blood perfusion) and λ (the partition coefficient of Gd-DTPA, which is proportional to extracellular volume fraction) were produced by subjecting DCE-MRI series to Kety analysis, and these images were compared with histological preparations from the imaged slices. Results: Strong correlations were found between fraction of necrotic tissue and fraction of voxels with λ > λL for λL values of 0.4 to 0.6. Binary λ images differentiating between λ values > λL and λ values < λL were found to mirror necrotic regions well in tumors with large necroses. However, necrotic foci that were small compared with the voxel size were not detectable. Conclusion: Clinically relevant images of necrotic tumor regions can be obtained for E-13 melanomas by subjecting Gd-DTPA-based DCE-MRI series to Kety analysis. © 2007 Wiley-Liss, Inc.