Dynamic contrast enhanced MRI (DCE-MRI) is an effective method of blood flow and microcirculation evaluation. Quantitative DCE-MRI parameters (ie, the contrast agent transfer rate between blood and tissue [Ktrans], contrast agent backflow rate constant [Kep], and extravascular extracellular fractional volume [Ve]) derived from pharmacokinetic modeling (Tofts modeling) have been widely studied recently.^[1] DCE-MRI perfusion analysis and generation of semi-quantitative or quantitative parametric maps is dependent on high temporal resolution of DCE-MRI. In this study we compared the association of dynamic contrast-enhanced (DCE)-derived quantitative parameters with the histologic grade, N-stage, epidermal growth factor receptor (EGFR) expression and K-RAS gene mutation of primary rectal cancer.35 patients with rectal adenocarcinoma confirmed by pathology underwent MR imaging before surgery. Research sequences included DCE MR imaging. We set 41 phases of Gd-enhancement scanning, 5 seconds for one phase and the first phase without contrast agent injection. In all patients, surgery was performed without neoadjuvant therapy. The region-of-interest (ROI) was selected based on diffusion weighted imaging (DWI), avoiding the area of cystic and necrosis. In order to better describe the tumor, at least 3 ROIs were chosen in different slices infiltrated by cancer. The two compartmental model was used in quantitative parameters (Ktrans、Kep、Ve) calculating. The average value of each parameter in different ROIs was recorded. The differences between the parameters of histopathologic parameters were assessed by using Chi-square test, including t-test (for normally distributed data) and Rank sum test (for non-normally distributed data). The histopathologic parameters included A (differentiation grade: A1, well differentiated; A2, moderately differentiated; A3, poorly differentiated), B (N-stage: B1, lymph nodes involvement; B2, lymph nodes without involvement), C (EGFR expression: C1, positive; C2, negative) and D (K-RAS gene mutation: D1, positive; D2, negative).Ktrans and Ve values were normally distributed data, while Kep values were non-normally distributed data. Mean Kep values of well differentiated group (A1) and poorly differentiated group (A3) were (1.522±0.271) min^-1 and (2.380±0.966) min^-1 respectively. There was a significant difference in mean Kep values between A1 and A3 (Z=-1.785, p=0.042, p<0.05 was statistically significant). Mean Ktrans values of B1 and B2 were (0.641±0.135) min^-1 and (0.497±0.155) min^-1 respectively. There was a significant difference in mean Ktrans values between B1 and B2 (t=2.655, p=0.009).The ROI region selection referent to Figure.1. Mean Ktrans values of C1 and C2 were (0.591±0.151) min^-1 and (0.480±0.157) min^-1 respectively. There was a significant difference in mean Ktrans values between C1 and C2 (t=2.138, p=0.02). Mean Kep values of C1 and C2 were (2.246±0.913) min^-1 and (1.541±0.408) min^-1 respectively. There was a significant difference in mean Kep values between C1 and C2 (Z=-2.426, p=0.007). There was no significant differences in Ktrans, Kep and Ve values when stratifying patients according to K-RAS gene mutation. The rest specific data was recorded in Table1-4.Significant correlations were found between Ktrans values and N-stage, Ktrans values and EGFR expression, Kep values and EGFR expression. DCE-derived quantitative parameters may be a promising imaging biomarker of tumor aggressiveness and prognosis.