Application And Evaluation Diffusion Weighted Imaging In Colorectal Cancer

Purpose: The purpose of this study was to evaluate the capability of apparent diffusion coefficient (ADC) measured by Diffusion Weight Imaging(DWI)for early detection of tumor response in a mouse model during chemotherapy,and to discuss the mechanism of changes of ADC referring to histopathological findings.Materials and Methods:32 Athymic mice with HCT116 xenografts on right rear flank were allocated into four groups: control, 5Fu, oxaliplatin and 5-Fu/oxaliplatin combined. T1,T2 and diffusion weighted images were acquired before therapy and in 1,3,7,11,15,20,25,30days after therapy. Pretreatment and posttreatment changes in ADC and volume of tumors were calculated and compared changes in ADC with tumor doubling growth delay. MRI were compared with histopathological findings at the same time.Results:1. All treated tumors showed decreased mean tumor ADC values 1-3days after initialization of therapy,histologic examination showed cell swell but no tumor necrosis.Except the tumors receiving 5Fu(P =0.07),the other tumors showed increased mean tumor ADC values 7-11days after initialization of therapy (P<0.05) before redecreasing in 15day and returning to pretreatment values within 20days posttherapy.Histologic examination showed tumor necrosis in 7-11days posttrestment and tumor regeneration in 15day posttreatment.2. The increase in mean tumor ADC showed a strong positive correlation (r=0.86,P<0.05) with mean tumor doubling growth delay. No correlations between pretreatment ADC and changes in tumor volumes after therapy were seen(P>0.05).Conclusions:1. Dynamic changes in mean ADC values of tumors correlated with histologic examination findings.2. DWI has potential to early detect of tumor response. Early(7-11days) posttreatment changes in mean ADC values correlated with treatment outcome. Purpose:To evaluate the accuracy of Computor Tomography(CT), Magnetic Resonace Imaging(MRI), and MRI with Diffusion Weight Imaging(DWI-MRI) for demonstrating the invovled lymph node in patients with colorectal cancer.Material and Methods:35 patients with clinical diagnosis of colorectal cancer had undergone MR imaging acquisition, who had operation within one week. 25 of them had undergone CT scanning after MR acquistion on the same day. Three groupes readers prospectively and independently analysed the CT imaging, MR imaging without DWI and MR imaging with DWI. Readers identified and characterized all lymph node by using a scale of 1-5 (1, definitely involvement; 5, definitely non-involvement). Prospetive imaging interpretations were compared directly with pathologic results.Results:On a node-by-node basis, the overall accuracy of CT imaging, MRI without DWI and MRI with DWI were respectively 56%,57.1% and 74.3%. Analyzed by the statistics ofχ2, MRI with DWI had medium relationship with pathologic results and kappa value is 0.536(p<0.05). No statistically relationship between the definition of the involved lymph node using CT ang MRI without DWI and pathologic results was found. The Kappa values were respectively 0.138 and 0.150 (p<0.05).Conclusion: MRI with DWI is more accurately than the other two imaging protocol for definition of the involved lymph node in patients with colorectal cancer.