Measuring breast volume in hypertrophy: laser scanning or water displacement?

Background: The accurate determination of intact breast volume facilitates preoperative planning for women with breast hypertrophy and, in some jurisdictions, is essential in order to justify breast reduction surgery. Not all practitioners have access to magnetic resonance imaging (MRI) or three dimensional (3D) laser scanning facilities, so the purpose of this study was to determine whether water displacement of the intact breast is an effective substitute method of measurement in women with breast hypertrophy. Methods: A prospective cohort study of breast hypertrophy patients was undertaken. The volume of a total of 322 breasts were determined using water displacement and 3D laser scanning; 194 preoperatively and 128 at 12 months following breast reduction surgery. Pearson correlations, linear regression and Bland-Altman analyses were used to compare the methods of breast volume assessment. Results: The mean breast volume according to 3D laser scan was 1440 millilitres (SD = 588 millilitres) and for water displacement was 1419 millilitres (SD = 811 millilitres). There was a strong linear association between breast volumes as measured using water displacement and 3D laser scanning using a Pearson correlation (r = 0.89, p < 0.001). However, using the Bland-Altman analysis, the two methods were found not to be in agreement, with water displacement values consistently larger than 3D scan values. Conclusions: Despite the strong linear association, water displacement is not an accurate enough tool to be used as a substitute for 3D laser scanning, and therefore not an optimal method of breast volume measurement in women with breast hypertrophy