Emerging Technologies in Face and Body Contouring (eBook)

1 Three-dimensional Imaging for Emerging Technologies in Body Contouring

Isabel Robinson and Pierre Saadeh

Abstract

Initially adopted by craniofacial surgeons, three-dimensional imaging technology has more recently expanded into the fields of breast and body contouring. These systems create value pre-, intra-, and postoperatively by facilitating a more objective conversation with patients on preoperative expectations, enabling the creation of personalized cutting guides and implants, and allowing surgeons to more accurately quantify their results over time. While currently limited by cost and technical training requirements, as these technologies continue to develop they are likely to become an indispensable resource in the body contouring surgeon’s armamentarium.

Keywords: Three-dimensional (3D) imaging, CADCAS, body contouring, cephalometrics, mammometrics, ultrahigh-sensitive optical microangiography

Table 1.1 Summary of 3D imaging technologies’ technical points, applications, and points for consideration

1.1 Introduction

3D imaging is a powerful emerging technology in the field of body contouring. Body contouring inherently deals with three-dimensional changes and relationships, and yet preoperative planning and postoperative assessment has historically relied on two-dimensional representations. With the advent of 3D imaging, volumetric analysis can be performed and visualized with an accuracy that 2D photographs are incapable of meeting. This enables surgeons to give patients a better understanding of their likely surgical outcomes and to ensure mutual understanding about surgical goals. It also provides a quantitative means of assessing outcomes and volume-based changes over time in order to further refine technique and optimize surgical outcomes. Newly-developing 3D imaging technologies are advancing the understanding of microvasculature1 and allowing surgeons and patients to experiment with various aesthetic outcomes using virtual simulations in real time.2 3D imaging revolutionizes the way surgeons are able to visualize patient data and holds great potential for both clinical and research applications.

1.2 History of 3D Imaging in Plastic Surgery

The history of 3D imaging begins with stereophotogrammetry, the practice of estimating three-dimensional coordinates on an object’s surface by using photographs of the object taken from different positions. The technique affords a more nuanced understanding of three-dimensional and volumetric relationships than traditional two-dimensional photography. Mannsbach originally suggested applying stereophotogrammetry to the fields of medicine and dentistry in 1922, and in 1939 Zeller first published a contour map of a man’s face using a stereocamera.3 It was not until 1944, however, that stereophotogrammetry was applied in a clinical setting, with Thalmann using the technique to diagnose orthodontic pathology.3

Since then many variations upon the technique have developed, most notably computer-assisted systems that greatly improve the speed and depth of analysis. Such advances include optical flow tracking, which incorporates time into three-dimensional analyses to give the user the ability to track soft tissue changes immediately during motion or longitudinally after surgery. One such iteration is 3D speckle tracking, in which white makeup is first applied to the patient’s face or other surfaces of interest. Black makeup is then dotted over the white, creating a speckled appearance that a computer can detect. In a craniofacial case, the patient then makes a series of facial expressions that displace the speckles while the computer tracks and analyzes these changes, producing a report on the patient’s facial expressivity. Newer technologies, such as the Di4D optical flow tracking software (Glasgow, Scotland), are able to track facial motion by digitally creating a mesh over a patient’s face and tracing changes to it over time, thereby obviating the need for makeup application. One of the newest developments in the field of three-dimensional medical imaging is ultrahigh sensitive optical microangiography (UHS-OMAG), with which Doppler monitoring of blood cell movement is able to produce 3D maps of capillary microvasculature in the skin after five seconds of scanning.1

What follows will be a review of current clinical applications of three-dimensional imaging technologies like optical flow tracking and UHS-OMAG to the practice of body contouring. Applications to breast and facial surgery will be emphasized as the majority of existent research on 3D imaging technologies comes from these subspecialties. However, many of the principles discussed apply equally to most body contouring procedures.

1.3 Preoperative Benefit of 3D Imaging

As early as 1978, computer-assisted cephalometric readings were described by Malmgren et al, as a means of quantifying the appearance of bony structures in the head.4 In 1987, Guyuron expanded the concept of cephalometrics into soft-tissue analysis, describing quantitative standards for measuring the nose to aid in rhinoplasty planning.5 Classical cephalometrics involves taking manual readings of anatomical landmarks and then tracing them by hand onto acetate paper to assess facial and dental harmony. Cephalometric planning has been used in the diagnosis and treatment planning of a wide range of craniofacial pathologies. The advent of digital cephalometric technology has dramatically increased the speed with which these measurements can be performed and the level of volumetric detail that can be assessed.6 With a computer-assisted digital cephalometric analysis system (CADCAS), the patient’s 3D image is captured through stereophotogrammetry. Software then automatically identifies facial landmarks and calculates relevant volumes and distances. Computer-assisted cephalometric measurements have been shown repeatedly to produce results that correlate strongly with manually-derived values.6,7

A challenge in aesthetic breast surgery is the lack of normative databases relative to craniofacial practice. Traditionally aesthetic breast surgery planning and outcome assessment has been based off qualitative discussion between the surgeon and patient. This makes developing digital assistance programs, which are inherent quantitative, difficult. Nevertheless, efforts have been made to standardize breast surgery evaluation with the aid of three-dimensional imaging. To this end, Karp et al describe the emerging principle of mammometrics as a tool for breast surgery planning and evaluation through three-dimensional volumetric analysis.2 As with cephalometrics, mammometrics involves using 3D imaging systems to photograph the patient and then identifying key landmarks on the resulting three-dimensional representation. Unlike in craniofacial surgery, which has CADCAS systems that can automatically identify important landmarks, the development of 3D breast imaging systems is relatively new and so automatic image interpretation is still in its infancy. As such, for 3D breast imaging programs the surgeon must either fine-tune breast landmarks identified by the software or manually identify key landmarks from which the software derives relevant volumes. Karp et al suggest including total breast volume, volumetric distribution, and breast projection among the volume...