Purpose: to evaluate dysprosium-enhanced MR imaging for differentiation between morphologically intact and necrotic tumor tissue in a tumor model. Material and Methods: A human colon carcinoma was transplanted subcutaneously into 9 nude (immunodeprived) rats. MR imaging was performed before and after injection of the dysprosium agent Dy-DTPA-BMA. T1-, T2- and T2*-weighted sequences were acquired. the tumors were dissected, histological sections were prepared, and compared with corresponding MR images. Results: in intact tissue, the MR signal intensity in the T2- and T2*-weighted images decreased after Dy injection and the delineation of the intact regions were sharp and corresponded well to the gross histological sections. Conclusion: Dy-enhanced MR imaging facilitated the differentiation between intact and necrotic tumor tissue.
