A retrospective analysis of digital stereotaxis in breast screening

Digital imaging systems have been introduced into the assessment process for breast screening and should help to make the procedure quicker and reduce the trauma. However, there is concern that digital stereotaxis could have a negative impact on the accuracy of tissue sampling procedures. The objective of this study was to deduce the impact of digital stereotaxis on the assessment process in breast screening. A retrospective study was undertaken in 28 centres that performed assessments in the UK breast screening programme. Quality assurance (QA) data from 7750 women assessed using conventional stereotaxis (from 25 units) were compared with those from 4743 women assessed using digital stereotaxis (from 14 units). All the data relate to women having biopsies. The data used show the pre-operative result recorded at the core biopsy compared with the overall outcome after surgery. From this, QA parameters are calculated which are used to deduce the performance of screening programmes. Complete sensitivity, specificity (full), the positive predictive value (PPV) for B3 biopsies and the suspicious rate had statistically significant increases (p<0.05, p<0.01, p<0.05 and p<0.05, respectively) and the specificity (biopsy), false-negative rate and inadequate rate from cancers had statistically significant decreases (p<0.01, p<0.0005 and p<0.0005, respectively). One of the other QA measures improved to meet the target standard set, i.e. PPV (B5). It is concluded that digital stereotaxis has contributed to significant improvements in the assessment process, although the improvements shown in this study cannot be wholly attributed to the introduction of digital stereotaxis.