Impact of background parenchymal enhancement levels on the diagnosis of contrast-enhanced digital mammography in evaluations of breast cancer: comparison with contrast-enhanced breast MRI

Purpose To compare the diagnostic performances of contrast-enhanced digital mammography (CEDM) and breast MRI in evaluations of breast cancer, with a focus on the impact of background parenchymal enhancement (BPE) levels. Methods The present study included women who underwent CEDM and breast MRI to evaluate the disease extent of breast cancer between January 2018 and December 2019. Readers judged BPE levels (minimal-mild or moderate-marked) on CEDM, and were asked to assign findings suggesting malignancy using the following criteria: (1) enhancement other than BPE and (2) BI-RADS 4/5 calcifications without enhancement. On MRI, BI-RADS 3 and BI-RADS 4/5 lesions were evaluated as benign and malignant, respectively. The diagnostic performances of CEDM and MRI were compared separately between women with minimal-mild BPE and those with moderate-marked BPE. Results Sixty-nine patients comprising 43 postmenopausal and 26 premenopausal women were included in the present study. In total, 195 lesions (94 malignant and 101 benign) were identified. The sensitivity and specificity of CEDM for the diagnosis of all lesions were 90.8 and 91.5% with minimal-mild BPE and 79.3 and 76.2% with moderate-marked BPE, respectively. The sensitivity and specificity of MRI were 90.0% and 71.0% with minimal-mild BPE and 87.5% and 78.1% with moderate-marked BPE, respectively. The accuracy of CEDM was significantly superior to that of MRI in women with minimal-mild BPE on both CEDM and MRI ( p = 0.002). Regarding the negative impact of a correct diagnosis on CEDM, the odds ratio of “moderate-marked BPE” was 0.382. Conclusion In patients with minimal-mild BPE, the diagnostic performance of CEDM was superior to that of MRI.