3D dynamic contrast-enhanced MRI of rectal carcinoma at 3T: Correlation with microvascular density and vascular endothelial growth factor markers of tumor angiogenesis

Purpose: To determine how dynamic contrast-enhanced (DCE) MRI at 3T correlates with rectal carcinoma angiogenesis. Materials and Methods: Three-dimensional (3D) DCE MRI was performed in 38 patients (23 males, 15 females, mean age 60 years) with histologically-confirmed rectal carcinoma at 3T. Time-intensity curves MCs) were used to measure peak enhancement ratio (ERpeak, time to peak enhancement (T-peak) first enhancement time (Tfirst-enhance), and uptake rate for rectal tumor, normal rectal wall, and gluteal muscle. After tumor resection, microvascular density (MVD) and vascular endothelial growth factor (VEGF) expression were determined using immunohistochemistry (IHC) stains on available specimens (N = 24) to correlate with DCE MRI. Results: Rectal carcinoma showed higher ERpeak (3.0 +/- 0.9 vs. 1.9 +/- 0.9, P < 0.001), higher uptake rate (2.8 +/- 1.5/minute vs. 1.2 +/- 0.9/minute, P < 0.001), earlier T-peak (88 +/- 56 seconds vs. 124 +/- 72 seconds, P = 0.027), and earlier Tfirst-enhance (34 +/- 6 seconds vs. 40 +/- 7 seconds, P = 0.008) than normal rectal wall. Adenocarcinoma had shorter T-peak compared to signet cell carcinoma (77 +/- 48 seconds vs. 160 +/- 62 seconds, P = 0.004). T-peak was negatively correlated with MVD (r = -0.516, P = 0.01) and the mean T-peak was significantly earlier for the VEGF-positive group compared to the VEGF-negative group (57 +/- 17 seconds vs. 107 +/- 64 seconds, P = 0.021). Conclusion: DCE MRI parameters help predict rectal tumor angiogenesis measured by MVD and VEGF expression and discriminate malignant from normal tissue.