Mammographic analysis of calcifications

Abstract

Because mammographically detected calcifications are frequently the only sign of breast cancer, the breast radiography equipment, screen-film imaging package, and film processing should be optimized to detect such calcifications. For this purpose, dedicated units with molybdenum targets, microfocal spot magnification capability, reciprocating grids, and high output x-ray tubes are required. With the greater use of state-of-the-art mammography, intraductal carcinoma, or DCIS, manifested only by calcifications is being detected more frequently than ever. DCIS can be of the comedo, cribriform, or micropapillary types. Comedocarcinoma, characterized by linear and branching (casting) calcifications, is the most aggressive type, and it has the highest rate of recurrence after breast-conserving surgery. Cribriform and micropapillary calcifications are characteristically punctate and vary in size and shape. In addition to histologic type, the recurrence of DCIS is related to its extent at detection and whether adequate tissue was removed at the time of breast-conserving surgery. Biopsies for suspicious calcifications should be followed immediately by specimen radiography to verify their removal. If breast-conserving surgery is elected for DCIS, the resected segment of tissue should be examined with pathologic techniques designed to determine whether the margins are clear of tumor. For DCIS and invasive cancers with extensive intraductal component, microfocus magnification mammography over the surgical site is recommended prior to radiotherapy to identify any residual tumor calcifications. Although state-of-the-art mammography is very sensitive in the detection of calcifications, it is low in specificity, thus resulting in a large number of false-positive mammograms and a relatively low true-positive biopsy rate. While some benign calcifications cannot be distinguished from those of malignancy, the number of biopsies for benign conditions can be decreased by careful analysis of the mammograms in a search for features indicating benignity.