Correlations of 3T DCE-MRI quantitative parameters with microvessel density and size of human colorectal cancer in a xenograft mouse model

Abstract

Objective: The aim of this study was to investigate the correlation between quantitative DCE-MRI parameters and microvascular density (MVD) in a human colon cancer xenograft mouse model using 3 Tesla MRI.Materials and methods: A human colon cancer xenograft model was produced by subcutaneously inoculating 1x106 DLD-1 human colon cancer cells into the right hind limbs of 10 mice. The tumors were allowed to grow for 2 weeks and then assessed using MRI. DCE-MRI was performed by tail vein injection of 0.3 mmol/kg of gadolinium. A region of interest (ROI) was drawn at the midpoints along the z-axes of the tumors, and Toft model analysis was performed. The quantitative parameters (Ktrans, Kep and Ve) from the whole transverse ROI and the hotspot ROI of the tumor were calculated. Immunohistochemical microvessel staining was performed and analyzed according to Weidner’s criteria at the corresponding MRI sections. The Mann-Whitney test and Spearman’s rho correlation analysis were performed to prove the existence of a correlation between the quantitative parameters and MVD.Results: Whole transverse ROI of the tumor showed no significant relationship between the MVD values and quantitative DCE-MRI parameters. In the hotspot ROI, there was a difference in MVD between low and high group of Ktrans and Kep that was almost statistically significant (p=0.06, P=0.07 respectively). Also, the correlation of Ktrans and Kep with MVD was found to be inverse (r = -0.61, P = 0.06 in Ktrans ; r = -0.60, P = 0.07 in Kep).Conclusions: Quantitative parameters measured by hotspot ROI in T1 weighted DCE-MRI provided better histological correlation than using whole transverse ROI. Among the quantitative parameters, Ktrans and Kep were correlated with MVD in this colon cancer mouse model.