2618. Factors Associated with False Negative Screen by Digital Breast Tomosynthesis: Lessons Learned From an 8-Year Experience at a Single Center
Authors * Denotes Presenting Author
  1. Wenhui Zhou *; Stanford University Medical Center
  2. Jonathan Phuong; Stanford University Medical Center
  3. Sydney Payne; Stanford University Medical Center
  4. Shelby Payne; Stanford University Medical Center
  5. Debra Ikeda; Stanford University Medical Center
  6. Eric Rosen; Stanford University Medical Center
Digital breast tomosynthesis (DBT) was designed to improve breast cancer detection, yet some cancers are not detected at DBT. There is limited data describing contributing factors for false negative (FN) DBT examinations. We performed this study to identify clinical and imaging determinants of FN results in DBT breast cancer screening.

Materials and Methods:
A retrospective review of 69,594 screening DBTs performed between March 2014 and March 2022 identified 51 FN exams, for a rate of 0.8 per 1000 screens. Two MQSA-certified radiologists evaluated the FN DBT screening exams, categorizing them as negative (no findings), nonspecific (minimal or subtle findings), or missed (obvious findings). We performed analyses of patient demographics, breast cancer risk factors, patient symptoms, breast density and mammographic findings. We used the Pearson's chi-squared test to compare categorical variables, and used a t-test to compare continuous variables. All statistical tests were 2-tailed; we considered p less than 0.05 statistically significant.

Of 51 FN DBT screens, the mean age of diagnosis was 60 years (SD = 12 years) and the mean time between screening and diagnosis was 7.1 months (range 0.5 to 12 months). On retrospective review, 69% (35/51) cancers were negative, 31% (16/51) cancers were missed and none had non-specific findings. Negative cases were more frequently associated with extremely dense breast tissue (p = 0.032). Missed mammographic findings included masses (14/16, 87.5%) and calcifications (2/16, 12.5%). Contributing factors for missed cases included: adjacent dense breast tissue (8/16, 50%), one-view findings (6/16, 37.5%), developing asymmetries (4/16, 25%), distracting findings (3/16, 18.8%), post-surgical changes (2/16, 12.5%), benign appearing masses (2/16, 12.5%), edge of image (2/16, 12.5%), patient positioning (1/16, 0.1), very few calcifications (1/16, 0.1%) and poor image quality (1/16, 0.1%).

The majority of the false-negative DBT screens were negative without identifiable findings on retrospective review. Women with extremely dense breast tissue were predisposed to both negative and missed exams by DBT screening. Increased vigilance to areas of high density in women with dense breasts might help to avoid delayed diagnosis in this patient population.