Influence of Marker Number and Position on Accuracy of Breast Measurement With Three-Dimensional Camera.

Background: The VECTRA H1 three-dimensional (3D) imaging system (Canfield Scientific, Parsippany, NJ) enables easy 3D image construction and measurement. Although the number and positions of markers on the skin for image synthesis might affect accuracy of measurements, few studies have mentioned the possibility. This study investigated the accuracy and reproducibility of distance measurements using VECTRA H1, focusing on the number and positions of markers.

Methods: A total of 3, 5, or 7 markers were attached to a female breast model including lateral markers 6 cm from the midline and photographed with VECTRA. Five markers were configured in more two ways, with the lateral markers either positioned 3 cm outside the midline (narrow interval) or 9 cm outside the midline (wide interval). 3D models were created three times under each condition, for a total of 15 models. Differences (measurement error) between measured values on 3D models and actual measured values were verified for six distances, such as distance between the nipples.

Results: The average difference was 11.1 mm with 3 markers (95% confidence interval (CI), 4.38-17.7 mm, p = 0.0028). In comparison, average difference was -0.395 mm (-0.866 to 0.0763 mm, p = 0.095) with 5 markers, and 0.139 mm (-0186 to 0.465 mm, p = 0.379) with 7 markers, all less than 1 mm. Average difference with narrow interval 5 markers was larger than one with wide interval.

Conclusions: In 3D imaging of the breast using VECTRA H1, distance measurements offering clinically satisfactory accuracy can be made by setting appropriate marker conditions.

Level Of Evidence V: This journal requires that authors assign a level of evidence to each article. For a full description of these Evidence-Based Medicine ratings, please refer to the Table of Contents or the online Instructions to Authors www.springer.com/00266 .