Transformation of the female breast during compression at mammography with special reference to the importance for localization of a lesion.

The effects of compression during mammography were studied in 187 breasts. The aims of this study were to investigate: 1) How the skin moves, 2) how the gland tissue is transformed, 3) if there is a relationship between outer and inner alterations and 4) the practical implications for aspiration biopsy. In this study, several experiments were carried out to investigate the effects of compression during clinical mammography in adult female breasts. The transformation of the breast during compression was investigated by means of external skin markings and internal markings using the biopsy needle and the hookwire at preoperative localization. The extent of the mammary gland was measured in the different standard projections during mammography. The calculation of the depth of a lesion during cranio-caudal compression was performed on the latero-medial radiographs. The result was checked with water-soluble radiographic contrast medium. The mean value of differences between observed and calculated depth was 3.7 mm. 1. The breast transforms during compression. 2. The biopsy needle in the breast and the barium markings on the skin incline ventrally in 96 per cent during latero-medial compression. The preoperative hookwire inclines ventrally in 92 per cent. 3. The extension of the gland parenchyma (the longest diagonal) is almost equal in all standard projections, including the medio-lateral oblique one. 4. The skin in the inframammary sulcus is firmly attached to the thoracic wall. This form of fixation determines principally the movements of the breast and limits the transformation during compression. 5. The movements of the skin are connected to the movements of the dense tissue, gland parenchyma. There is a connection between the ventral and descending inclination. These inclinations are caused by the same transformation of the breast. 6. Due to the regular movements of the breast during different compression directions, it is possible to predict the location of a lesion in three dimensions from standard mammograms.