Objective To explore the value of ~(18)F 2-deoxy-2-fluoro-d-glucose(~(18)F-FDG)positron e-mission tomography (PET)/computed tomographic (CT) imaging and CT perfusion in evaluating metabolic and blood flow characteristics in breast cancer.Methods 32 women with untreated breast masses were both ex-amined with ~(18)F-FDG PET/CT and CT perfusion at the same day.All the lesions were confirmed histopothologi-cally by surgery or biopsy.The PET/CT images were analyzed semi-quantitatively.CT perfusion images were analyzed using the GE perfusion 3 soft package.The findings of two modalities above were commed with patho-logical diagnosis.Results There were significant differences between standardized uptake values (SUVs) of ~(18)F-FDG of benign tumors and breast cancer (Wilcoxon test:P=0.000 3,T=15.000,u=3.433,C=1).Differ-ences of SUVs between the center and periphery of breast Inasses were also significant.In addition.the SUVs were related to the pathological type and the grading of tumors.In the CT perfnsion,the differences of perfusion including bloodflow (BF),blood volume(BV)and permeability surface area product (PS) values between tumor and normal breast tissue were statistically significant(t=8.065,P<0.000 1;t=2.769 1,P=0.011 5;T~+=253.000 0,T~- =0.000 0,P<0.000 1)respectively.The differences of BF,BV and PS values between pe-ripheral zone and central portions of tumor were also statistically significant (t=8.015 8,P<0.000 1;t=2.243 4,P=O.017 9;t=3.485 7,P=0.002 2),respectively.Conclusion ~(18)F-FDG PET/CT imaging and CT peffusion reveal the metabolic and blood flow characteristics,and reflect biological behavior of breast tumor indirectly and have important value for the diagnosis and prognosis of breast cancer.