Aim: The BreastIdea Volume Estimator (BIVE) is an internet based application that uses an algorithm to estimate breast volume based on 2D images . This technique has previously been validated in a population of cisgender women (1), but not in men or transgender women due to anatomical differences that occur during male puberty. Validation in the chests of men and transgender women will allow use of this technique to estimate breast volume for clinical and research purposes.
Methods: 2D photography (frontal, lateral views) was performed on transgender women prior to commencing (used as reference population for male chests) and 6 months post commencement of feminising hormone therapy. BIVE was used to estimate breast volume by two researchers independently and compared to a gold standard calculation of breast volume using a 3D scanner. The mean absolute difference (MAD) was calculated to assess accuracy. Intraclass coefficients (ICC) were calculated to assess absolute and relative reliability.
Results: The breast volume of 102 breasts of 41 transgender women (median(IQR) age 26 (23-30) years, BMI 24.6 (21.2-29.0) kg/m2) was estimated using the BIVE application and compared to volumes obtained from 3D modelling. For frontal views, the MAD±SD was 8.27±8.01 mL for observer 1 and 9.58±12.78 mL for observer 2. The standard error of measurement was 0.20 mL for observer 1 and 0.93 mL for observer 2. The relative reliability ICC (95%CI) was 0.993 (0.989–0.996) for observer 1 and 0.949 (0.920–0.967) for observer 2. The absolute reliability ICC (95%CI) between observers was 0.980 (0.969–0.987) suggesting good correlation.
Conclusion: The BIVE application can be used to reliably estimate breast volume in cisgender men and transgender women. This provides a low cost and accessible option for clinicians and researchers in the outpatient setting. Limitations include initial user training to use the application proficiently.