New Technologies for the Assessment of Breast Surgical Outcomes

Methodology 

The 3-D/four-dimensional (4-D) breast-dedicated prototype laser scanner is made up of a handheld device, including a charge-coupled device (CCD) camera rigidly coupled to a spot laser source and seven passive markers (Figure 1). Two more motion analyzer cameras were part of the experimental setup for handheld device tracking and the acquisition of patient motion by means of the real-time detection of multiple passive markers placed on the chest.

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Figure 1. A, A handheld camera rigidly coupled to a spot laser source and seven passive markers. B, Acquisition setup.

The device was first tested for accuracy on an anthropomorphic phantom (a device or object designed to emulate measurements of in vivo movements); afterwards, seven female volunteers underwent a dynamic breast shape survey. The selected women represented relevant morphologic categories and included both subjects who had undergone cosmetic or reconstructive breast surgery and those with no history of breast surgery. Each hemithorax was scanned separately; the volunteers sat on a chair with both arms raised laterally at 90° to expose hidden areas such as the inframammary fold (IMF), which in some cases were acquired separately from the remaining hemithorax by suspending the breast. The two motion analyzer cameras were used to acquire kinematics data produced during the performance of a specific motor task, through the 3-D localization of passive markers placed on the patient's thorax. The obtained digital models were analyzed with a software tool called Breast Shape Analyzer that was developed in the Department of Plastic and Reconstructive Surgery, Fondazione IRCCS Istituto Nazionale dei Tumori and that enables linear and surface measurements. A false color-mapping description of each subject's thorax surface curvature was also calculated.

Results 

Laser scanning of the anthropomorphic phantom revealed that the percentage of points featuring a distance below 1 mm in comparison to the computed tomographic (CT) scan was 71.2 ± 6.1% (mean ± standard deviation [SD]; Figure 2). With the handheld device, it was possible to scan the IMF and the lateral aspects of the breast (Figure 3). Curvature mapping on 3-D models was one of the most interesting parameters. Areas with a fully positive curvature (spheres) were blue (curvature values close to 1); regions with a completely negative curvature (saddles) were red (curvature values close to −1). Flat or almost flat areas were yellow or green, with curvature close to 0. Such color mapping revealed large surface alterations in a woman who had undergone expander insertion in a two-stage reconstruction (Figure 4). Tiny modifications were also shown in a patient with a cosmetically pleasing implant-based reconstruction and contralateral augmentation. The curvature assessment revealed a slight increase of round (nearly blue) areas on the upper-inner pole of the healthy augmented breast, which was probably caused by a moderate degree of glandular ptosis that rendered the subpectoral implant more visible. Conventional photography clearly revealed these data, but did not enable quantitative measurements; by contrast, the 3-D mesh warranted precise measurements of local geometric properties of the breast surface (Figure 5). Elaboration and representation of breast dynamic behavior during common motor tasks (eg, walking, running, sitting, and lying) was also possible. A demonstration of laser scanning and the use of the Breast Shape Analyzer tool can be found online at http://aestheticsurgeryjournal.com/ (Video 1).

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Figure 2. Laser scanning of the anthropomorphic phantom revealed that the percentage of points featuring a distance below 1 mm in comparison to the computed tomography scan was 71.2 ± 6.1% (mean ± standard deviation).

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Figure 3. Large hidden areas, A, can also be detected in the large and ptotic breast, B.

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Figure 4. A, A 54-year-old woman underwent three-dimensional mesh (B) and curvature mapping (C) which shows her with a temporary expander in comparison to the untreated contralateral breast.

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Figure 5. A, A 37-year-old woman is shown in the second stage of a two-stage breast reconstruction with contralateral breast augmentation (subpectoral implants). Three-dimensional mesh (B) and curvature mapping (C) show tiny alterations of curvature on the augmented breast.

Discussion 

Several attempts to quantitatively assess breast shape have been reported in the literature. These range from calculations based on two-dimensional photographs (also assisted by dedicated software) to much more sophisticated 3-D digital acquisitions of the chest wall surface.1, 2, 3, 4, 5 Most of these studies are based on limited validation and none of them has made a real impact on clinical practice. The authors of previous studies have usually based their surveys on the translation of visual terminologies (full, empty, symmetric, etc) into quantitative data and consequently attempted to calculate volumes and perform symmetry analysis. To our knowledge, only one study has been able to correctly validate volume measurements calculated by a 3-D laser scanner and compare the results to those calculated using magnetic resonance imaging (MRI).3 However, this proposed method also did not affect everyday practice.

Conclusions 

The prototype breast-dedicated 4-D laser scanner reliably describes the breast surface not only in a static position, but also at specific postures or during motion of the body. This breast kinematics assessment may lead to the quantitative static and dynamic assessment of surgical outcomes, quantitative validation of scientific reports on breast cosmetic and reconstructive surgery, intraoperative assessment of breast shape and, as a further application, virtual assistance in implant selection and positioning. Complete clinical and technical validation will provide the plastic surgeon with a powerful tool in auditing breast surgery.