Abstract: Background and purpose: The density of fibrous gland tissue is closely related to the occurrence and development of breast cancer. This study aimed to compare the diagnostic value of mammography, cone beam breast CT (CBBCT) and contrast-enhanced CBBCT in dense breast lesions of clinical patients. Methods: The study included 80 patients who underwent mammography and CBBCT examinations from May 2012 to August 2014. The CBBCT and mammography diagnostic results of 80 breasts were reviewed and compared with pathological results. We measured the lesion CT values of CBBCT images before and after enhancement, and classified the degree and type of enhancement. Results: The area under the receiver operating characteristic (ROC) curves of mammography, CBBCT and contrast-enhanced CBBCT of the 80 breasts were 0.934(95%CI: 0.855-0.977), 0.971(95%CI: 0.907-0.996) and 0.975 (95%CI: 0.912-0.997), respectively. With BI-RADS 4b as the critical value, the sensitivities of the three imaging techniques were 72.5%, 75.0% and 92.5% respectively. The P values were all<0.01. It was showed that most of the malignant tumors were obviously inhomogeneous, and the way of benign tumor enhancement was diversified. The enhanced degree of malignant tumor was obviously higher than that of benign tumor. There was significant difference in CT values between the benign and malignant tumors（t=-4.180, P<0.01）. Conclusion: In this study, the diagnosis of breast malignant tumors by contrastenhanced CBBCT showed higher sensitivity and accuracy. It has significant value in identifying the benign and malignant tumors in dense breast of clinical patients.

Key words: Cone beam breast CT, Mammography, Breast cancer