V9-01: Three-Dimensional Photography as a Tool for Characterization of Penile Deformity in Peyronie’s Disease
Non-curvature penile deformities are prevalent and bothersome manifestations of Peyronie's disease (PD) that can result in functional impairment and psychological distress. The quantitative metrics that are currently used to describe these deformities are inadequate and non-standardized, which has historically been a barrier to clinical research and patient care. Our aim is to introduce three-dimensional photography as a technique to improve the evaluation of patients with PD, partially by the measurement of erect penile volume (EPV) and percent erect penile volume loss (EPVL), and to assess the reliability of measurements acquired by 3D photography.
Six penis models were constructed using computer-assisted design software, and physical models were produced using a 3D printer. 3D photographs of each model were captured in triplicate by 4 observers using an inexpensive 3D camera (Structure Sensor, Occipital, San Francisco, CA). Computer software (Blender, Amsterdam, Netherlands) was used to generate automated measurements of EPV, penile length, minimum circumference, and maximum circumference. 3D images were then digitally reconstructed to restore each image to a non-deformed shape. Percent EPVL was calculated for each model as the percent difference between the EPV of the original model and the EPV after digital reconstruction. The automated measurements were then statistically compared to measurements obtained using water displacement experiments and a tape measure.
On average, 3D photography was accurate to within 0.1% for measurement of penile length. It overestimated maximum and minimum circumference by averages of 5.0% and 1.8%, respectively; overestimated EPV by an average of 8.6%; and underestimated percent EPVL by an average of 1.9%. All inter-test, inter-observer, and intra-observer ICC values were greater than 0.75, reflective of excellent methodological reliability.
Erect penile volume and percent EPVL are novel, highly descriptive metrics that may be useful in describing all variants of non-curvature, volume-loss deformities resulting from PD. These metrics can be quickly, accurately, and reliably determined using computational analysis of 3D photographs. Clinical research using 3D photography for assessment of EPV and percent EPVL will empower clinicians and researchers to better understand the clinical impact of penile volume-loss deformities and to study how these deformities respond to therapy.
Funding: Columbia University College of Physicians & Surgeons