Optimal Gadolinium Dose Level for Magnetic Resonance Imaging (MRI) Contrast Enhancement of U87-derived Tumors in Athymic Nude Rats for the Assessment of Photodynamic Therapy

摘要

Introduction: This study aims to determine the effect of varying gadopentetate dimeglumine (Gd-DTPA) dose on Dynamic Contrast Enhanced-Magnetic Resonance Imaging (DCE-MRI) tracking of brain tumor photodynamic therapy (PDT) outcome. Methods: We injected 2.5×10~5 U87 cells (derived from human malignant glioma) into the brains of six athymic nude rats. After 9, 12, and 13 days DCE-MRI images were acquired on a 9.4 T micro-MRI scanner before and after administration of 100, 150, or 200 μL of Gd-DTPA. Results: Tumor region normalized DCE-MRI scan enhancement at peak was: 1.217 over baseline (0.018 Standard Error [SE]) at the 100 uL dose, 1.339 (0.013 SE) at the 150 uL dose, and 1.287 (0.014 SE) at the 200 uL dose. DCE-MRI peak tumor enhancement at the 150 uL dose was significantly greater than both the 100 uL dose (p < 3.323E-08) and 200 uL dose (p < 0.0007396). Discussion: In this preliminary study, the 150 uL Gd-DTPA dose provided the greatest T1 weighted contrast enhancement, while minimizing negative T2~* effects, in DCE-MRI scans of U87-derived tumors. Maximizing Gd-DTPA enhancement in DCE-MRI scans may assist development of a clinically robust (i.e., unambiguous) technique for PDT outcome assessment.