Correlation of dynamic contrast-enhanced MRI perfusion parameters with angiogenesis and biologic aggressiveness of rectal cancer: Preliminary results

Purpose: To investigate whether quantitative parameters derived from dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) are correlated with angiogenesis and biologic aggressiveness of rectal cancer. Materials and Methods: A total of 46 patients with rectal cancer underwent DCE-MRI. Using a two-compartmental model, quantitative parameters (K^trans, k_ep, v_e, and iAUC) were calculated from the whole-transverse region of interest (ROI) and high K^trans area ROI of entire tumors. Histological specimens were analyzed for tumor size; T/N stage; lymphatic, vascular, perineural invasion; expression of epidermal growth factor receptor (EGFR); and KRAS gene mutations. Tumor angiogenesis was evaluated based on the microvessel density (MVD) and the expression level of the vascular endothelial growth factor. Correlations of the DCE-MRI parameters with histological markers and angiogenesis were determined using Student's t-test and analysis of variance (ANOVA). Results: The mean k_ep from high K^trans area ROIs showed a significantly positive correlation with MVD (P = 0.030, r = 0.514, R² = 0.264). The mean k_ep from the whole-transverse ROIs showed a significant inverse correlation with T stage (T1 vs. T2-4, P = 0.021). EGFR-positive cancer displayed higher mean K^trans (P = 0.045) and k_ep (P = 0.038) than EGFR-negative cancer in whole-transverse ROIs. Conclusion: These preliminary results suggest that the determination of k_ep of high K^trans area permits the noninvasive estimation of tumor angiogenesis in rectal cancer and that DCE-MRI parameters can be used as imaging biomarkers to predict the biologic aggressiveness of the tumor and patient prognosis.