Correlations of DCE-MRI with morphologic, angiogenic, and molecular prognostic factors in rectal cancer

Abstract

PURPOSE: The purpose of this study was to investigate the correlations between parameters of dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) and prognostic factors in rectal cancer.MATERIALS AND METHODS: We studied 29 patients with rectal cancer who underwent DCE-MRI with a three Tesla scanner prior to surgery. Signal intensity on DCE-MRI was independently measured by two observers to test reproducibility. A time-signal intensity curve was generated, from which four semiquantitative parameters were calculated: steepest slope (SLP), time to peak (Tp), relative enhancement during a rapid rise (Erise), and maximal enhancement (Emax). Morphologic prognostic factors including T stage, N stage, and histologic grade were identified. Tumor angiogenesis was evaluated in terms of microvessel count (MVC), microvessel area (MVA), and expression of vascular endothelial growth factor (VEGF). As molecular factors, the mutation status of the K-ras oncogene and microsatellite instability were assessed. DCE-MRI parameters were correlated with each prognostic factor using bivariate correlation analysis. A p-value of <0.05 was considered significant.RESULTS: Erise was significantly correlated with N stage (r=-0.387 and -0.393, respectively for the two independent data), and Tp was significantly correlated with histologic grade (r=0.466 and 0.489, respectively). Emax was significantly correlated with MVC (r=-0.435 and -0.386, respectively). SLP (r=-0.532 and -0.535, respectively) and Erise (r=-0.511 and -0.446, respectively) were significantly correlated with MVA. No significant correlations were found between DCE-MRI parameters and T stage, expression of VEGF, K-ras mutation, or microsatellite instability.CONCLUSION: DCE-MRI may provide useful prognostic information in patients with rectal cancer.