Reply: The Evolution of Photography and Three-Dimensional Imaging in Plastic Surgery

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I would like to commend Dr. Kantor for his innovative approach toward three-dimensional surface imaging and scanning. His letter is in response to our recent publication entitled “The Evolution of Photography and Three-Dimensional Imaging in Plastic Surgery” (Plast Reconstr Surg. 2017;139:761–769), in which we highlight the increasing adoption of three-dimensional surface imaging in various aspects of aesthetic and reconstructive plastic surgery. The letter points out that, at present, the cost of three-dimensional capture systems remains relatively high, thus preventing widespread use of this technology. To overcome this limitation, he introduces the concept of creating three-dimensional facial scans with ReCap 360 (Autodesk, Inc., San Rafael, Calif.), a free software application that can be downloaded on a smartphone. The process represents a form of stereophotogrammetry technology that merges multiple facial images. The example that he shows in Figure 1 demonstrates a three-dimensional face scan that was created by stitching 64 individual two-dimensional photographs.
I, like the author, feel strongly that rapid adoption of this technology will be dependent on the development of low-cost, user-friendly capture devices such as the one he describes. Of note, a number of technology companies have introduced, or are aggressively pursuing, similar software programs that can capture three-dimensional images from portable devices. This growing interest toward handheld capture is not unique to medicine but is in fact quite rampant among other industries that have a need for rapid digitization of objects for applications such as reverse engineering or three-dimensional printing. It is therefore reasonable to predict that numerous type of portable, inexpensive, three-dimensional scanning devices will soon be available that can be modified for medical use.
Regardless of scanning technology hardware, however, precision will continue to be of the utmost importance as we continue to explore uses in the medical arena. From the images and content provided by Dr. Kantor’s letter, it is difficult to assess the accuracy of the three-dimensional facial scan with his technique. Although he does note that there are over 900,000 vertices in the image, it is important for readers to understand that “vertices” alone do not necessarily equal accuracy. During three-dimensional conversion or capture, a set of data points are generated to create a “point cloud.” Three-dimensional surfaces are typically then generated by creating a network of triangles over the vertices of the point cloud. Therefore, although it is important that many data points exist, it does not necessarily denote that these points are placed accurately in three-dimensional space. With this in mind, I would invite physicians and scientists interested in this technology to study the accuracy of these newly emerging portable scanners, and compare these images with more traditional stereophotogrammetric capture systems. Color wrap analysis could easily be performed to help answer this question.
Ultimately, the clinical value of three-dimensional imaging will depend on its end user (in this case, surgeons). At the moment, there are a number of exciting potential uses for plastic surgeons, including (1) medical documentation, (2) three-dimensional simulation and virtual surgical planning, (3) three-dimensional printing, and (4) virtual reality. Medical documentation is particularly exciting, as this may supplement and even ultimately replace traditional two-dimensional photography. Imagine if surgeons could easily capture three-dimensional photographs during patient consultations. If accurate, the data provided by three-dimensional images would far exceed what we gain from standard two-dimensional photographs. Moreover, surgeons could gain a better understanding of true postoperative changes and the evolution that occurs over time. A wonderful example of this is recent work by Val Lambros looking at the facial aging process using three-dimensional imaging.1 Dr.
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