Stereophotogrammetric three‐dimensional photography is an accurate and precise planimetric method for the clinical visualization and quantification of human papilloma virus‐induced skin lesions

BACKGROUND: The quantification of human papilloma virus (HPV)‐induced skin lesions is essential for the clinical assessment of the course of disease and the response to treatment. However, clinical assessments that measure dimensions of lesions using a caliper do not provide complete insight into three‐dimensional (3D) lesions, and its inter‐rater variability is often poor. OBJECTIVE: The aim of this study was to validate a stereophotogrammetric 3D camera system for the quantification of HPV‐induced lesions. METHODS: The camera system was validated for accuracy, precision and interoperator and inter‐rater variability. Subsequently, 3D photographs were quantified and compared to caliper measurements for clinical validation by Bland–Altman modelling, based on data from 80 patients with cutaneous warts (CW), 24 with anogenital warts (AGW) patients and 12 with high‐grade squamous intraepithelial lesions of the vulva (vulvar HSIL) with a total lesion count of 220 CW, 74 AGW and 31 vulvar HSIL. RESULTS: Technical validation showed excellent accuracy [coefficients of variation (CV) ≤ 0.68%] and reproducibility (CVs ≤ 2%), a good to excellent agreement between operators (CVs ≤ 8.7%) and a good to excellent agreement between different raters for all three lesion types (ICCs ≥ 0.86). When comparing 3D with caliper measurements, excellent biases were found for diameter of AGW (long diameter 5%), good biases were found for diameter of AGW (short diameter 10%) and height of CW (8%), and acceptable biases were found for the diameter of CW (11%) and vulvar HSIL (short diameter 14%, long diameter 16%). An unfavourable difference between these methods (bias 25%) was found for the assessment of height of AGWs. CONCLUSION: Stereophotogrammetric 3D imaging is an accurate and reliable method for the clinical visualization and quantification of HPV‐induced skin lesions.