Objective: Augmentation implants pose a challenge for radiologists. Displacing the implant allows slightly more breast tissue to be visualized than the standard compression views. The objective of this study was to verify the agreement between craniocaudal (CC) views and CC with implant displacement (CC-ID), mediolateral oblique (MLO) and MLO-ID and the inter- and intraobserver agreement of mammographic images for finding abnormal images.
Methods: The main outcomes [BI-RADS® normal=1,2; abnormal=3,4,5)] were analysed by 3 readers (reader1; reader 2, 1st round, reader 2, 2nd round) in 360 women with breast implants. Comparison between CC/CC-ID and MLO/MLO-ID, and degree of agreement for mammographic images between researchers were made using Kappa index. Proportions were calculated using a 95% confidence interval (95%CI).
Results: A total of 87 abnormal findings were identified by reader 2, 2nd round. Abnormal findings were observed in CC-ID=18.8% (68 out of 360; 95%CI=15.1%-23.2%) compared to CC=10.8% (39 out of 360; 95%CI=8%-14.4%, k=0.49); in MLO=10.5% (38 out of 360; 95%CI=7.7%-14.1%) compared to MLO-ID=15.8% (57 out of 360; 95%CI=12.4%-19.9%, k=0.55). The CC-ID was the view that singly identified more abnormal findings (20 out of 87; 23%; 95%CI=15.4% to 32.8%) and the CC was the view that least detected abnormal findings (1 out 87; 95%CI=0.2% to 6.2%). The inter- and intraobserver agreement between readers views was 0.67 and 0.74 respectively.
Conclusions: In women with breast augmentation implants, all views are necessary to identify breast tissue abnormalities. In our sample, the inter- and intraobserver agreement were "substantial".
Keywords: Breast; Breast Implants; Breast augmentation; breast cancer; mammography.