2353. Significance of Different Enhancement Types on Contrast-Enhanced Mammography: How Often is There Association with Malignancy?
Authors * Denotes Presenting Author
  1. Geunwon Kim *; Beth Israel Deaconess Medical Center
  2. Tejas Mehta; Beth Israel Deaconess Medical Center
  3. Rashmi Mehta; Beth Israel Deaconess Medical Center
  4. Valerie Fein-Zachary; Beth Israel Deaconess Medical Center
  5. Vandana Dialani; Beth Israel Deaconess Medical Center
  6. Linda Du; Beth Israel Deaconess Medical Center
  7. Jordana Phillips; Beth Israel Deaconess Medical Center
Despite increasing use of contrast-enhanced mammography (CEM), there is limited data evaluating findings seen on recombined images (RI). Our purpose is to determine how often enhancement on CEM corresponds to low-energy (LE) findings and malignancy.

Materials and Methods:
All diagnostic CEM exams performed between December 2015 and December 2019 were retrospectively reviewed under institutional IRB approval. Enhancement type on RI and associated findings on LE were reviewed. Outcome by pathology or 1-year imaging/clinical follow-up were used for each enhancement finding.

Of 431 exams performed, 240 (55.7%) exams had at least one finding with enhancement on recombined images and a total of 389 findings with enhancement were recorded. Of the 389 findings, 217 (55.8%) were described as mass enhancement, 137 (33.7%) as non-mass enhancement (NME), and 41 (10.5%) as foci. Of these, 102/217 (47.0%) of mass enhancement, 33/131 (25.2%) of the NME, and 2/41 (4.9%) of the foci were malignant. Mass as enhancement type had the highest positive predictive value (PPV) (82.52% (95% confidence interval(CI): 76.36%-87.35%) as compared with NME (42.31%, CI: 36.86%-47.95%) or focus (18.18%, CI:11.13%-28.27%), regardless of the finding type. When there is associated finding on LE, 85/102 (83.3%) of mass as enhancement type and 28/66 (42.4%) of NME were cancer. No (0%, 0/5) foci with LE findings were associated with cancer. Without associated findings on LE, 16.7% (17/102) mass enhancement, 15.2% (5/33) NME, and 100% (2/2) foci without LE findings were cancers, though enhancements without LE correlate were more likely benign (p<.00001 for mass and NME).

Mass enhancement on recombined images is most predictive of malignancy, followed by NME, especially when associated with LE finding. When not associated with LE findings, enhancement types are more likely to be benign, however, given that malignancy still occurs in 16.7% masses, 15.2% NME, and 100% foci, these findings should be viewed with suspicion.