Comparison of Mass Size Measurements: Synthesized Mammography Versus Full-Field Digital Mammography

To compare mass size measurements between synthesized mammography (SM) and full-field digital mammography (FFDM), and to assess interobserver agreement for those measurements.

One hundred and forty-three patients who underwent FFDM and digital breast tomosynthesis acquisitions during the same compression session were included in the study. Two observers with four-and 1-year experience with digital breast tomosynthesis and SM images, respectively, measured mass sizes independently in two different sessions that were 2 weeks apart, and were blinded to each other. The first session included only FFDM images, and the second session included only SM images. Largest dimension of masses was measured in millimeters. Paired t test was used to compare differences in size measurements between FFDM and SM images. Intraclass correlation coefficient test was used to analyze interobserver agreement. Bland-Altman analyses were performed to evaluate agreements between the imaging techniques and between the observers.

The mean mass sizes on FFDM and SM images were 20.27 ± 14.10 and 18.50 ± 13.05 mm, respectively, for the first observer and 21.56 ± 14.84 and 19.89 ± 13.68 mm, respectively, for the second observer. The mass size measurements were significantly different between FFDM and SM for both observers (p < 0.001). Range of measurement errors, defined as 95% limits of agreements between two imaging techniques for observers 1 and 2 were ±1.96*1.36 mm, and ±1.96*1.53 mm, respectively. Range of measurement errors, defined as 95% limits of agreements between two observers for SM and FFDM were ±1.96*3.68 mm, and ±1.96*3.35 mm, respectively.

The measured mass sizes were significantly smaller on SM than FFDM images, and the interobserver differences for both of the imaging techniques were greater than the differences measured between FFDM and SM images.