Juhun Lee

Validation of Stereophotogrammetry of the Human Torso

The objective of this study was to determine if measurements of breast morphology computed from three-dimensional (3D) stereophotogrammetry are equivalent to traditional anthropometric measurements obtained directly on a subject using a tape measure. 3D torso images of 23 women ranged in age from 36 to 63 who underwent or were scheduled for breast reconstruction surgery were obtained using a 3dMD torso system (3Q Technologies Inc., Atlanta, GA). Two different types (contoured and line-of-sight distances) of a total of nine distances were computed from 3D images of each participant. Each participant was photographed twice, first without fiducial points marked (referred to as unmarked image) and second with fiducial points marked prior to imaging (referred to as marked image). Stereophotogrammetry was compared to traditional direct anthropometry, in which measurements were taken with a tape measure on participants. Three statistical analyses were used to evaluate the agreement between stereophotogrammetry and direct anthropometry. Seven out of nine distances showed excellent agreement between stereophotogrammetry and direct anthropometry (both marked and unmarked images). In addition, stereophotogrammetry from the unmarked image was equivalent to that of the marked image (both line-of-sight and contoured distances). A lower level of agreement was observed for some measures because of difficulty in localizing more vaguely defined fiducial points, such as lowest visible point of breast mound, and inability of the imaging system in capturing areas obscured by the breast, such as the inframammary fold. Stereophotogrammetry from 3D images obtained from the 3dMD torso system is effective for quantifying breast morphology. Tools for surgical planning and evaluation based on stereophotogrammetry have the potential to improve breast surgery outcomes.

A Novel Quantitative Measure of Breast Curvature Based on Catenary

Quantitative, objective measurements of breast curvature computed from clinical photographs could be used to investigate factors that impact reconstruction and facilitate surgical planning. This paper introduces a novel quantitative measure of breast curvature based on catenary. A catenary curve is used to approximate the overall curvature of the breast contour, and the curvature measure is extracted from the catenary curve. The catenary curve was verified by comparing its length, the area enclosed by the curve, and the curvature measure from the catenary curve to those from manual tracings of the breast contour. The evaluation of the proposed analysis employed untreated and postoperative clinical photographs of women who were undergoing tissue expander/implant (TE/Implant) reconstruction. Logistic regression models were developed to distinguish between the curvature of breasts undergoing TE/Implant reconstruction and that of untreated breasts based on the curvature measure and patient variables (age and body mass index). The relationships between the curvature measures of untreated breasts and patient variables were also investigated. The catenary curve approximates breast curvature reliably. The curvature measure contains useful information for quantifying the curvature differences between breasts undergoing TE/Implant reconstruction and untreated breasts, and identifying the effect of patient variables on the breast shape.

3D Symmetry Measure Invariant to Subject Pose During Image Acquisition.

In this study we evaluate the influence of subject pose during image acquisition on quantitative analysis of breast morphology. Three (3D) and two-dimensional (2D) images of the torso of 12 female subjects in two different poses; (1) hands-on-hip (HH) and (2) hands-down (HD) were obtained. In order to quantify the effect of pose, we introduce a new measure; the 3D pBRA (Percentage Breast Retraction Assessment) index, and validate its use against the 2D pBRA index. Our data suggests that the 3D pBRA index is linearly correlated with the 2D counterpart for both of the poses, and is independent of the localization of fiducial points within a tolerance limit of 7 mm. The quantitative assessment of 3D asymmetry was found to be invariant of subject pose. This study further corroborates the advantages of 3D stereophotogrammetry over 2D photography. Problems with pose that are inherent in 2D photographs are avoided and fiducial point identification is made easier by being able to panoramically rotate the 3D surface enabling views from any desired angle.

A shape constrained parametric active contour model for breast contour detection

Quantitative measures of breast morphology can help a breast cancer survivor to understand outcomes of reconstructive surgeries. One bottleneck of quantifying breast morphology is that there are only a few reliable automation algorithms for detecting the breast contour. This study proposes a novel approach for detecting the breast contour, which is based on a parametric active contour model. In addition to employing the traditional parametric active contour model, the proposed approach enforces a mathematical shape constraint based on the catenary curve, which has been previously shown to capture the overall shape of the breast contour reliably [1]. The mathematical shape constraint regulates the evolution of the active contour and helps the contour evolve towards the breast, while minimizing the undesired effects of other structures such as, the nipple/areola and scars. The efficacy of the proposed approach was evaluated on anterior posterior photographs of women who underwent or were scheduled for breast reconstruction surgery including autologous tissue reconstruction. The proposed algorithm shows promising results for detecting the breast contour.

Breast Curvature of the Upper and Lower Breast Mound: 3D Analysis of Patients who Underwent Breast Reconstruction

Quantitative and objective methods to evaluate the morphology of the reconstructed breast may help plastic surgeons improve their surgical practice, and thus ultimately help breast cancer survivors derive the intended psychosocial benefits of reconstruction. Recently, we developed a quantitative and objective way to measure the curvature of the breast on standard clinical photographs. Here we conduct a more-in depth analysis of breast curvature using 3D images of the human torso. The analysis is based on the catenary curve, which is a perfectly flexible and inextensible string of uniform density supported by two distinct points. In this study, we used our curvature measure to study the upper and lower curvature of the breasts (breast curvature) of 9 patients who underwent breast reconstruction surgery. Breast reconstruction was performed using the autologous flap in 4 patients (5 breasts) and a tissue expander/implant (TE/Implant) in 5 patients (6 breasts). To assess the breast curvature, the outlines of the upper and lower breast were first obtained from coronal sectional views that are created from multiple parallel planes to the chest wall, which are spaced about 1 cm apart from each other. Then the curvature measure was extracted from the catenary contours fitted on the resulting outline of each sectional view. Our data show that breast curvatures of the upper and lower breast mound vary from the most anterior part of the breast mound to the chest wall. Moreover, our data suggest possible trends on the upper and lower breast curvature for different reconstruction types. For example, the opposite relationship was found between the upper and lower breast curvature for autologous and TE/Implant reconstructed breasts. In this study, we demonstrated a breast curvature measure for evaluating the outcome of breast reconstruction, especially for the curvature of the upper and lower breast mounds, based on 3D torso images of patients.

Quantitative measures of facial expression for patients with head and neck cancer

In addition to changes in facial morphology, head and neck cancer treatment can impact the facial expression. Quantification of changes in facial expression, particularly of smiling, would enable a deeper understanding of the relationship between physical changes and psychosocial adjustment in patients being treated for facial cancer. This study proposes 48 quantitative facial expression measures, which consist of the length normalized distances and slopes between 27 manually annotated fiducial points on standard 2D clinical photographs of patients with head and neck cancer. Using the proposed measures, the maximum intensity of smiling for patients with head and neck cancer prior to their treatments was compared to that of a sample from a healthy population. A total of 7 facial expression measures captured statistically significant differences between patients with head and neck cancer and healthy individuals. These measures suggest that patients with head and neck cancer are less expressive than people without head and neck cancer. This study is the first attempt to quantify the facial expression of patients with head and neck cancer and to build a foundation for studying how surgical interventions may affect their facial expressions. Moreover, this study lays the groundwork for future investigation of the relationship between facial expression and psychosocial adjustment in cancer patients.

Associations between psychosocial functioning and smiling intensity in patients with head and neck cancer

Increasing attention is being given to developing quantitative measures of facial expression. This study used quantitative facial expression analysis to examine associations between smiling intensity and psychosocial functioning in patients with head and neck cancer (HNC). Smiling intensity of 95 HNC patients was measured using 48 quantitative measures calculated from facial photographs with and without a smile. We computed a composite smiling intensity score for each patient representing the degree of similarity to healthy controls. A lower composite score indicates that the person is less expressive, on average, than healthy controls. Patients also completed self-report measures assessing domains of body image and quality of life (QOL). Spearman rank correlations were computed to examine relationships between composite scores and psychosocial functioning. Composite scores were significantly correlated with multiple measures of body image and QOL. Specifically, decreased smiling intensity was associated with feelings of dissatisfaction with one’s body, perceived negative social impact of body image, increased use of avoidance as a body image-coping strategy, reduced functional well-being, and greater head and neck cancer-specific issues. To the best of our knowledge, this is the first study to demonstrate associations between an objectively quantified facial expression (i.e. smiling) and psychosocial functioning. Most previous studies have measured facial expression qualitatively. These findings indicate that smiling intensity may serve as an important clinical indicator of psychosocial well-being and warrants further clinical investigation.

Eigen-disfigurement model for simulating plausible facial disfigurement after reconstructive surgery.

BackgroundPatients with facial cancers can experience disfigurement as they may undergo considerable appearance changes from their illness and its treatment. Individuals with difficulties adjusting to facial cancer are concerned about how others perceive and evaluate their appearance. Therefore, it is important to understand how humans perceive disfigured faces. We describe a new strategy that allows simulation of surgically plausible facial disfigurement on a novel face for elucidating the human perception on facial disfigurement.MethodLongitudinal 3D facial images of patients (N = 17) with facial disfigurement due to cancer treatment were replicated using a facial mannequin model, by applying Thin-Plate Spline (TPS) warping and linear interpolation on the facial mannequin model in polar coordinates. Principal Component Analysis (PCA) was used to capture longitudinal structural and textural variations found within each patient with facial disfigurement arising from the treatment. We treated such variations as disfigurement. Each disfigurement was smoothly stitched on a healthy face by seeking a Poisson solution to guided interpolation using the gradient of the learned disfigurement as the guidance field vector. The modeling technique was quantitatively evaluated. In addition, panel ratings of experienced medical professionals on the plausibility of simulation were used to evaluate the proposed disfigurement model.ResultsThe algorithm reproduced the given face effectively using a facial mannequin model with less than 4.4 mm maximum error for the validation fiducial points that were not used for the processing. Panel ratings of experienced medical professionals on the plausibility of simulation showed that the disfigurement model (especially for peripheral disfigurement) yielded predictions comparable to the real disfigurements.ConclusionsThe modeling technique of this study is able to capture facial disfigurements and its simulation represents plausible outcomes of reconstructive surgery for facial cancers. Thus, our technique can be used to study human perception on facial disfigurement.

Towards a Case-Based Reasoning System for Predicting Aesthetic Outcomes of Breast Reconstruction

As many breast cancer survivors are candidates for multiple types of breast reconstruction, they need help visualizing possible outcomes to make optimal decisions about breast reconstruction. The purpose of this study was to develop a prototype of a system that could help women visualize possible breast reconstruction surgery results by displaying examples of reconstruction outcomes achieved by patients with similar pre-operative features. We present a prototype case-based reasoning (CBR) system that queries a database of women who have already undergone breast reconstruction surgery to retrieve a subset of cases that were pre-operatively similar to the test patient. Similarity is assessed in terms of features such as breast volume, patient age, and body mass index (BMI). In our prototype CBR system, the prior cases are reused in a straightforward manner; we simply present the post-operative 3D images of the cases that were pre-operatively similar to the test patient. The prototype CBR system was built on the data obtained from 47 patients. For each patient, we obtained 3D images before and six months after the initial breast reconstruction surgery. From these images, we quantified left and right pre-operative breast volumes. In order to retrieve cases that were pre-operatively similar to a given test patient, we applied the k-nearest neighbor algorithm (based on Euclidean distance) on the pre-operative features. We demonstrated the usefulness of our CBR system by presenting the sample query, which showed visually similar reconstructed breasts compared to the real reconstruction outcome.

Three-Dimensional Analysis of Facial Asymmetry of Healthy Hispanic Caucasian Children

The objective of this study was to conduct a quantitative analysis of facial asymmetry of healthy Hispanic Caucasian children residing in Central Texas, USA. 3D facial surface images of healthy Hispanic Caucasian participants (41 boys, 39 girls) currently residing in Central Texas, USA (aged 7 and 12 years) were obtained using a 3dMDcranial system (3dMD, Atlanta, GA) under an approved IRB protocol. Facial features of each hemiface (left and right) were quantified using 27 anthropometric distances between 22 facial landmarks computed from the 3D facial surface images. Two types of distances were included: 1) Euclidean (2 orbital, 3 nasal, 8 oral, and 6 profile) and 2) Geodesic (1 orbital, 1 nasal, 6 profile) distances. The ratio of each facial feature of the left hemiface to the corresponding facial feature of the right hemiface was calculated. The one-sample Student’s t test with a Bonferroni correction was employed to assess the extent of facial asymmetry. Overall, for both genders, the facial features from the right side are larger than those from the left side. It was found that healthy Hispanic Caucasian children have fairly symmetric faces. However, the data suggest that there is a statistically significant asymmetry of facial features for healthy Hispanic Caucasian children. For example, the ratio of the nostril (sbal – sn) was asymmetric for healthy Hispanic Caucasian boys and the ratio between the Geodesic distances from tragion to nasion (t – n) was asymmetric for both genders. The result of this study is consistent with previous studies of other racial/ethnic groups. This information will serve as reference data for surgeons who conduct reconstructive surgery for children with congenital deformities of their faces.