Variability of Breast Density Assessment and the Need for Additional Imaging: A Comparison between Computed Mammography and Digital Mammography

Objective: To determine the variability of breast density assessment and the need for additional imaging using computed radiography (CR) mammography versus digital radiography (DR) mammography. Study Design: Cohort study. Place and Duration of Study: Department of Radiology, The Aga Khan University Hospital, Karachi from March to June 2018. Methodology: Patients who underwent screening CR mammography, followed by DR mammography a year later, were selected. Only disease-free individuals were included in the study. Evaluation of breast density was done subjectively, using the breast imaging reporting and data system (BI-RADS) by two independent experienced radiologists. Statistical analysis was performed using the Wilcox Signed Rank-sum test to compare both modalities. Fisher Exact method was used to compare the need for ultrasound imaging. Results: A total of 295 patients were included in the study. The mean age of the patients was 52.76 +/- 0.64 years. There was a significant difference in the change of breast density when comparing both modalities (Z= -11.839, p <0.001). A statistically significant reduction in the need for further breast ultrasound was observed after DR mammography than with CR mammography (p <0.001). Conclusion: Use of DR mammography, especially in patients with dense breast parenchyma, is a better screening tool overall. It translates to better feasibility for the radiologist and is more economical for the patient. DR mammography decreases unnecessary imaging and leads to better visualisation, thus providing a more accurate categorisation of breast density.