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

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 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 lambda (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: Stroing correlations were found between fraction of necrotic tissue and fraction of voxels with lambda > lambda(L) for lambda(L) values of 0.4 to 0.6. Binary lambda images differentiating between lambda values > lambda(L) and lambda values < lambda(L) were found to mirror necrotic regions well in tumors with large necroses. However, necrotic foci that were small compared with. them 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.