Mammography Positioning Standards in the Digital Era: Is the Status Quo Acceptable?

OBJECTIVE. The objective of our study was to evaluate positioning of full-field digital mammography (FFDM) and digital breast tomosynthesis (DBT) compared with film-screen (FS) mammography positioning standards. MATERIALS AND METHODS. A retrospective study was conducted of consecutive patients who underwent screening FFDM in 2010-2012 and DBT in 2012-2013 at an academic institution. Examinations were performed by five experienced technologists who underwent updated standardized positioning training. Positioning criteria were assessed by consensus reads among three breast radiologists and compared with FS mammography data from a 1993 study by Bassett and colleagues. RESULTS. One hundred seventy patients (n = 340 examinations) were analyzed, showing significant differences between FFDM and DBT examinations (p < 0.05) for medial or inferior skin folds (FFDM vs DBT: craniocaudal [CC] view, 16% [n = 56] vs 23% [n = 77]; mediolateral oblique [MLO] view, 35% [n = 118] vs 45% [n = 154]), inclusion of lateral glandular tissue on CC view (FFDM vs DBT, 73% [n = 247] vs 81% [n = 274]), and concave pectoralis muscle shape (FFDM vs DBT, 36% [n = 121] vs 28% [n = 95]). In comparison with Bassett et al. data, all positioning criteria for both FFDM and DBT examinations were significantly different (p < 0.05). The largest differences were found in visualization of the pectoralis muscle on CC views and the inframammary fold on MLO views, inclusion of posterior or lateral glandular tissue, and inclusion of skin folds, with DBT and FFDM more frequently exhibiting all criteria than originally reported Bassett et al. findings. CONCLUSION. DBT and FFDM mammograms more frequently include posterior or lateral tissue, the inframammary fold on MLO views, the pectoralis muscle on CC views, and skin folds than FS mammograms. Inclusion of more breast tissue with newer technologies suggests traditional positioning standards, in conjunction with updated standardized positioning training, are still applicable at the expense of including more skin folds.