2015 Volume 24 Issue 1 Pages 113-122
The aim of this study was to analyze interobserver agreement in evaluation of breast composition and differences in sensitivity according to breast composition. [Materials and methods]In 51cases of breast cancer, which were confirmed either by operation or needle biopsy between April2011and March2012at Tsukuba Medical Center Hospital, pre- treatment two-view mammograms were available. Ninety-nine normal or benign cases were also chosen. Five qualified observers who had no information about the cases used two 5M pixel monitors and evaluated all1 50cases in terms of breast category and breast composition using four different classifications: the classification usually used by the observer, the classification prescribed by the Japanese mammography guidelines, a classification that takes into consideration whether ultrasound examination should be added, and the classification based on the BI-RADS classification, which assesses the area of fibro-glandular tissue. [Results]Interobserver agreement was higher for the classification prescribed by the Japanese mammography guidelines and the classification usually employed by the observer, compared with the other two classifications. The sensitivities were61.5~67.3% for the cases overall and69.6~81.2% for cases involving fatty breasts or breasts with scattered glands. The sensitivity for women aged50years or over was71.4~77.1%, regardless of breast composition. [Conclusion]Interobserver agreement was high for breast composition as defined by the Japanese guidelines. For fatty breasts or breasts with scattered glands, the breast cancer sensitivity was almost the same as that for women aged 50years or over.