Usefulness of diffusion-weighted and perfusion-weighted MR in mouse C6 gliomas : correlation with histopathology

Abstract

Objective Diffusion/perfusion-weighted MRI (DWI、PWI) was performed to evaluate growth and vascularity of implanted C6 rat gliomas. Methods 36 female Wistar rats were implanted of C6 glioma cells intracerebrally. Between 1 and 4 weeks after implantation, eight to ten different rats were imaged with T_1WI, T_2Weighted imaging, DWI, PWI, and postcontrast T_1WI at each weekly time point. After MRI, each rat brain was examined histologically using HE and immunohistochemical staining for CD34. Results On DWIs, statistical differences of apparent diffusion coefficient (ADC) values for both the solid tumor component and peritumoral region were present comparing 3-4 weeks with 1-2 weeks after implantation (P0.01). ADC value for the solid tumor component was negatively correlated with tumor cellularity (r=-0.682,P0.01). Statistical difference of the maximal regional cerebral blood volume (rCBV_ max ) for the solid tumor components was present comparing 2-4 weeks with both 1-week after implantation and contralateral white matter (P0.01). Native vessel dilation in regions of normal brain at the periphery of the tumors at 1 week after implantation was observed, and rCBV_ max in these regions were elevated compared to the contralateral sides (t=3.88,P0.01). Prominent positive correlation was present between rCBV_ max of the solid tumor component and microvascular density (MVD) (r=0.716, P0.01). Conclusion Reduced ADC value for the solid tumor component is correlated with malignancy of C6 gliomas. rCBV_ max for the solid tumor component can evaluate tumoral microvessel in vivo, while those at the periphery may be useful for the differentiation between native vessel dilation of normal brain and angiogenesis of the tumor.