Three-Dimensional Photography for Quantitative Assessment of Penile Volume-Loss Deformities in Peyronie's Disease
Ezra J. Margolin, BA; Carrie M. Mlynarczyk, MD; John P. Mulhall, MD; Doron S. Stember, MD; Peter J. Stahl, MD
ONLINE: April 28, 2017 – The Journal of Sexual Medicine
Peyronie’s disease (PD) is a fibrotic disease of the penis, affecting the tunica albuginea and causing penile deformities. One of the most common deformities is curvature, but unilateral indentations, bilateral indentations (which result in an hourglass shape), and proximal and distal tapering of the penis are also possible.
Such deformities are often linked to erectile dysfunction, penile length loss, and depression.
Non-curvature deformities can cause a loss of erect penile volume (EPV). They may occur in conjunction with curvature.
There is no standardized system to quantitatively describe volume-loss deformities. This proof-of-concept study discusses the ways three-dimensional (3D) photographs might be used to develop metrics for this purpose.
Seven erect penis models were created with Blender, a 3D graphics software program. One was a normal form and the rest depicted typical deformities found in men with PD. Aside from the deformities, the models were identical, with the same height and diameter.
Next, 3D photographs of the models were taken with a Structure Sensor camera. Four different observers photographed each model in triplicate.
In the next step, 3D computer graphics software was used to analyze the 3D images in terms of curvature (in one model), EPV, length, maximum circumference, and minimum circumference.
The images of the penises with volume-loss deformities were then digitally reconstructed to resemble normal penises.
Using the volume of the reconstructed model, the researchers calculated the percent erect penile volume loss (EPVL) for each image.
Manual measurements from one observer were also conducted.
The median time for capturing the 3D images was 52 seconds. Processing the raw images and taking the measurements took 3 to 5 minutes, and reconstructing each model to determine percent EPVL took 1 to 3 minutes.
3D photography was accurate to within 0.6 cm (0.3%) for measurement of erect penile length. It overestimated maximum and minimum penile circumference by averages of 5.9 mm (4.2%) and 1.5 mm (1.6%), respectively. EPV was overestimated by an average of 11.2 cm3 (7.1%). Percent EPVL was underestimated by an average of 1.9%.
3D photography is a viable method for capturing penile deformities in men with PD. The approach takes little time, and the camera is affordable. Images may then be managed with an iPad or other mobile devices.
The benefits of 3D photography include the ability to assess PD reliably and the application of metrics such as EPV that may then be used in clinical studies as well.
Having images available can also help urologists track and document the progress of PD and its treatment and discuss that progress with patients using side-by-side comparisons. Clinicians would also have a way to separate clinical assessment of penile deformity from the pharmacologic erection, which might make patients feel more comfortable when discussing treatment options.
“In summary, we introduce a method using 3D photography that is quick, accurate, and relabel for the quantitative description of penile volume-loss deformity in penis models. Study of the feasibility, accuracy, and reliability of this approach in humans is ongoing,” the authors wrote.