Intra-observer agreement in single and joint double readings of contrast-enhanced breast MRI screening for women with high genetic breast cancer risks

Objectives: To examine intra-observer reliability (IR) for lesion detection on contrast-enhanced breast magnetic resonance images (MRI) for screening women at high risk of breast cancer in single and joint double readings, without case selection. Methods: Contrastenhanced breast MRIs were interpreted twice by the same independent reader and twice in joint readings. IR was assessed for lesion detection, normal MRI identification, mass, non-mass like enhancements (NMLE) and focus characterisation, and BI-RADS assessment. Results: MRI examinations for 124 breasts, 65 women (mean age 43.4y) were retrospectively reviewed with 110 lesions identified. Abnormal BI-RADS (3-5) classifications were found for 52.3% in single readings and 58.5% in joint readings. Seven biopsies were performed for 4 histologically confirmed cancers. IR for BI-RADS classifications was good for single (0.63, 95% CI: 0.49-0.77), and joint readings (0.77, 95% CI: 0.61-0.93). IR for background parenchymal enhancement (BPE) was moderate across single (0.53, 95% CI: 0.40-0.65) and joint readings (0.44, 95% CI: 0.33-0.56). IR for BI-RADS category according to each enhancement was poor for single (0.27, 95% CI: 0.10-0.44), and higher for joint readings, (0.58, 95% CI: 0.43-0.72). Conclusions: IR in BI-RADS breast assessments or BI-RADS lesion assessments are better with joint reading in screening for women with high genetic risks, in particular for abnormal MRI (BI-RADS 3, 4 and 5).