Abstract: A mass detection method based on bilateral information was proposed for dense mammograms.To improve the matching accuracy of symmetric regions,breast regions were extracted after removal of pectoral muscle and axilla part,and an anatomic coordinate system that only consisted of breast region was constructed.To reduce the false positive rate of mass detection,regions of interest(ROIs)were determined using both physiological and pathological characters besides the inherent information of the images.Feature distance of the local ternary pattern of breast gradient amplitude was employed to measure the similarity between matching pixels.The proposed method is tested on the clinical images provided by the breast center of Peking university people’s hospital.Experimental results show that the constructed coordinate system obtains better ROI matching performance.Compared with existing bilateral mass detection methods,the proposed method yields a lower false positive rate with the same mass detection accuracy.