Functional Magnetic Resonance Imaging In Assessing The Breast Cancer Response To The Chemotherapy-an Experimental Study

PRAT 1:Establishment of Breast Cancer Rat Model and its Use in the Study of Magnetic Resonance ImagingPurpose:To establish a rat model of breast cancer and evaluate the feasibility of this model in the examination of magnetic resonance imaging.Materials and Methods:Forty-five female Sprague-Dawley rats were inoculated with walker-256 breast carcinoma cells subcutaneously in the armpits.The MRI examinations were performed after the tumor achieved a volume of 1.5 cm³-2.0 cm³.Results:The overall rate of successful establishment of the model is 84.4%(38/45).All the images(100%) were well obtained on DWI analysis.The achievement ratio for MRS is 69.4%,and that for PWI is 36.1%.Conclusion:This breast cancer rat model is easy to establish and is valuable for the using in the study of magnetic resonance imaging.PRAT 2:Diffusion-weighted MR Imaging in evaluating the breast cancer response to chemotherapy in rat-an experimental study.Purpose:To evaluate the use of diffusion-weighted MR imaging to detect the early response of breast cancer to chemotherapy in a rat model.The advantages and limits of different methods were also compared.Materials and Methods:Walker-256 breast cancer cell implanted subcutaneously in left armpit of 24 female Sprague-Dawley rats(weight 200±10g).15 rats were treated with Doxorubicin and 9 served as controls.Diffusion weighted MR imaging was performed before and at 24 hours after treatment.The apparent diffusion coefficient(ADC) of the entire tumor or little ROI of each tumor was calculated with different b values(b=200,400,600,800,1000sec/mm²).The differences of the ADC values between pre-and post-chemotherapy were compared.The changes of the ADC histograms on the basis of diffusion weighted images with b=1000sec/mm² were also analyzed.Results:The ADC values of the entire tumor and little ROI did non show any significantly changes on different b values after Doxorubicin injection.As for ADC histogram analysis,however,all parameters which include the ADC_总mean(P≤0.001),ADC_1.1mean(P=0.026),ADC_1.3mean(P=0.009) increased significantly in chemotherapy group while no significant changes were found in control group.Mp_1.1(P=0.001)å’ŒMp_1.3 (P≤0.001) also increased after Doxorubicin treatment.Conclusion:Diffusion weighted MR Imaging has potential use for the early detection of response to chemotherapy and enables to discriminate between viable and necrotic tissues.PRAT 3:Evaluation of total choline with proton MR spectroscopy and its response to chemotherapy in breast cancer—an experimental study.Purpose:To evaluate the role of MR spectroscopy in assessing the early response of breast cancer to chemotherapy.Materials and Methods:Walker-256 breast cancer cell implanted subcutaneously in left armpit of 24 female Sprague-Dawley rats(weight 200±10g).15 rats were treated with Doxorubicin and 9 served as controls.MR spectroscopy imaging was performed before and at 24 hours after treatment.The peak height and area under curve of Cho peak were compared between the baseline and after the treatment.The changes of the peak height ratio and area under curve ratio of Cho/Lip were also analyzed.Results:the concentration of Cho decreased in chemotherapy group(Cho peak height,P＜=0.001;Cho area under curve,P=0.002) while no significant changes were found in control group.The Cho/Lip peak height ratio(P≤0.001) and area under curve ratio(P=0.002) also show significantly decrease after Doxorubicin treatment.Conclusion:The change in Cho concentration between baseline and 24 hours can serve as an indictor for predicting response to chemotherapy in breast cancer.