Three-dimensional digital imaging is as accurate and reliable to measure leg ulcer area as transparent tracing with digital planimetry

Objective: An accurate and reliable method for measuring venous leg ulcer (VLU) area is important in assessing treatment effects. The new three-dimensional (3D) LifeViz digital imaging system (QuantifiCare S.A., Valbonne, France) combines a compact, easy to use stereovision camera and image management software to provide 3D medical images. The aim of this prospective study was to investigate whether the 3D LifeViz digital imaging system could be considered a suitable alternative to manual transparent wound tracing for the measurement of VLU area and 4-week healing rates.

Methods: A prospective cohort study was conducted in two tertiary centers between November 2013 and January 2014. The intrarater variability of the digital imaging system was assessed by comparison of the target wound (TW) areas obtained at the inclusion visit (W0) and 2 days after W0 for each local rater. The inter-rater variability of the two methods at W0 and the study end visit was assessed using the TW area measurements obtained by local and central raters.

Results: A total of 36 consecutive outpatients, each presenting with at least one VLU and representing a total of 44 TWs, were recruited. At inclusion, comparable results were observed with both methods in terms of mean VLU area, showing a good correlation of the digital imaging method with the transparent tracing method (concordance correlation coefficient [CCC], 0.989; 95% confidence interval [C], 0.983-0.992). Furthermore, this system detected the same changes in the 4-week healing rate as the transparent tracing method, showing that both methods were equivalent in measuring changes in VLU areas over time (CCC, 0.996; 95% CI, 0.994-0.997). Strong intrarater and inter-rater concordances demonstrated good reproducibility of the digital imaging system for VLU area measurements (CCC, 0.994 [95% CI, 0.992-0.995] for intrarater variability; and CCC ≥0.99 for each center for inter-rater variability). Moreover, regardless of the operator measuring the VLUs, the reliability of image capture and image quality remained excellent.

Conclusions: The 3D LifeViz digital imaging system is a noncontact stereophotographic method that provides measurements of VLU area or changes in VLU areas that are as accurate and reliable as those obtained using the planimetry method and in conditions as close as possible to those of a clinical trial.