Arup Ray

Validation of a Vision-Based, Three-Dimensional Facial Imaging System

Objective The aim of this study was to assess the accuracy of a newly developed three-dimensional (3D) imaging system in recording facial morphology. Methods Twenty-one infants with cleft lip each had a full-face alginate impression taken at the time of primary lip repair, and a stone cast was constructed from each impression. Five anthropometric points were marked on each cast. Each cast was digitized, and the 3D co-ordinates of the five points were obtained using a co-ordinate measuring machine (CMM, Ferranti) of documented accuracy (9.53 μm). Each cast was scanned in four positions using a computerized stereophotogrammetry (C3D) system. The five points were located on the 3D images, and their 3D co-ordinates were extracted by three operators. The co-ordinate systems produced by C3D were aligned, via translation and rotation, to match the CMM co-ordinate system using partial ordinary procrustes analysis. The displacements of the adjusted C3D co-ordinates from the reference co-ordinates were then measured. Three different types of errors were identified: operator, system, and registration errors. Results Operator error was within 0.2 mm of the true co-ordinates of the landmarks. C3D was accurate within 0.4 mm. The average displacement of points over the 21 casts at four positions for the three operators was 0.79 mm (median 0.68). Conclusions The presented 3D imaging system is reliable in recording facial deformity and could be utilized in recording cleft deformities and measuring the changes following surgery

An appraisal of three methods of rating facial deformity in patients with repaired complete unilateral cleft lip and palate.

OBJECTIVES To evaluate the reliability of clinical assessment, two-dimensional color transparencies and three-dimensional imaging for evaluating the residual facial deformity in patients with repaired complete unilateral cleft lip and palate (UCLP) and compare the ratings of facial deformity made by health care professionals with those made by lay assessors. PATIENTS AND PARTICIPANTS Thirty-one randomly selected subjects aged 10 to 30 years with repaired complete UCLP. Five professionals and five laypersons evaluated each subjects residual cleft-related facial deformity using clinical assessment, two-dimensional color transparencies, and three-dimensional images. MAIN OUTCOME MEASURES The facial deformity of the full face, lip, nose, and midface were scored using a 5-point ordinal scale on two occasions with a 1-month interval. Intra- and interexaminer agreements were calculated from weighted kappa statistics. Bootstrap permutation tests were used to detect any differences in agreement. RESULTS Assessment of facial deformity showed good reproducibility across the three assessment media (kappa = 0.42 to 0.83, SE 0.08). Clinical assessment among lay assessors, however, was poor to moderate (kappa = 0.16 to 0.58, SE 0.07). For all assessors, there was no difference in the two nonclinical media relative to the standard clinical assessment for assessments of the full face (p =.377). For assessments of the lip or nose, transparency scores were in greater agreement with the clinical scores than were the three-dimensional assessment scores (p =.017 and.011, respectively). For rating the midface, the three-dimensional scores were in greater agreement with the clinical scores than were the color transparencies scores (p =.047). CONCLUSIONS In comparison with lay assessors, clinical assessment among professionals was more reproducible. This was not so for nonclinical media. The equivalence of using the color transparencies and three-dimensional media relative to the clinical assessment depends on the region of the face being considered.

Facial characterization of infants with cleft lip and palate using a three-dimensional capture technique.

Objective To characterize the soft tissue features of infants with unilateral cleft lip (UCL) and unilateral complete cleft lip and palate (UCLP) prior to primary surgery and compare with noncleft controls. Design Prospective controlled capture of the facial morphology of infants using a noninvasive three-dimensional stereophotogrammetry method. Participants 23 children with presurgical cleft: 11 UCL (M = 6, F = 5); 12 UCLP (M = 9, F = 3), and 21 noncleft controls (M = 7, F = 14) were imaged at approximately 3 months of age (range 10 to 16 weeks). Main Outcome Measure Accurate, repeatable quantification of facial soft tissues in infants with clefts prior to surgery. Results Significant differences (p < .05) were found between the UCLP group and UCL and control groups in anatomical and soft nose width, cleft-side alar wing length, and nasal tip horizontal displacement. Both cleft groups were significantly different from controls and from each other in cleft-side nostril dimensions, alar wing angulation, columella angle, and alar base to corner of mouth dimension; alar base width; and soft tissue defect in nose and the lip and philtrum length bordering the cleft. Significant differences between clefts and controls were identified in the nostril and philtrum on the noncleft side. Conclusions The use of children with UCL as controls for UCLP studies is inappropriate. This technique overcame the limitations of direct measurement of infant faces to aid the surgeon in the planning and subsequent re-evaluation of surgical rationale.

Three-dimensional facial characteristics of Caucasian infants without cleft and correlation with body measurements.

Objective The aim of this study was to characterize the soft tissue facial features of infants without cleft and to report on the correlation between these with weight, length, and head circumference. Design This was a prospective study using a noninvasive three-dimensional (3D) stereophotogrammetry (C3D) system to capture the images of the participants. Landmarks were identified on the 3D facial images. Means and SDs were derived for facial distances and angles. A facial asymmetry score was calculated for each image. Two sample Students t tests, Pearsons correlation coefficients and analysis of covariance were used to ascertain any gender differences and determine whether these could be explained by weight differences. Participants Eighty-three infants, 41 boys and 42 girls, were captured at rest with their lips apart, at approximately 3 months of age. Results Significant sex differences, of 1 to 2 mm, were found in several facial dimensions, such as face height and nose width. The larger facial measurements correlated significantly with body measurements. Analysis of variance confirmed these differences could be explained by differences in weight. There were no sex differences in the nose/mouth width ratios or in any of the angles measured, suggesting that there may be little sex difference in shape. A slight degree of asymmetry in the faces of infants without cleft was detected. Conclusions Comparisons between noncleft controls and infants with cleft should take cognizance of normal age and sex variations in height and weight that occur among infants.

Investigation into accuracy and reproducibility of a 3D breast imaging system using multiple stereo cameras

BACKGROUND The aim of this study was to evaluate the validity of a three-dimensional (3D) multiple stereo camera system for objective breast assessment. METHODS A multiple stereo camera system, which consisted of four pods and eight cameras, two cameras on each pod, developed by Glasgow University, was used. Nine specially shaped plaster breast models were captured once, 3Dmodels were constructed and the volume of each plaster model was measured 10 times by the breast analysis tool (BAT) software. A comparison was conducted with water displacement method, and measurements were repeated 10 times. The breast of six live volunteers was captured six times; from each breast capture, a 3D model was constructed and the volume was measured with BAT software. Breast volume assessment by the water displacement method was repeated six times. RESULTS In all plaster casts, the discrepancies in volume measurements between 3D imaging and water displacement methods did not exceed 40 cc. The overall mean relative difference was 5%. The differences of the two methods were not significant at p = 0.189, overall mean difference: 11.1 cc and 95% confidence interval (CI) was (-6.732, 28.976). In the live models, the differences in breast volume measurements between the 3D imaging and water displacement methods were significant at p ≤ 0.017, overall mean difference: 207.05 cc and 95% CI (56.12, 357.98). Measurements by 3D imaging were consistently smaller. In the live models, 3D imaging overall was a more reproducible method for measuring breast volume than the water displacement method with a standard deviation of 36 units cc(-1) and 62.6 units cc(-1), respectively. CONCLUSIONS The 3D breast imaging system using multiple stereo cameras was accurate for measuring the volumes of breast-shaped plaster models, and it was more reproducible than the water displacement method in live models. 3D imaging is a reliable method for the comparative assessment of breast volume.

Facial symmetry in unilateral cleft lip and palate following alar base augmentation with bone graft: a three-dimensional assessment.

Objective: The aim of this study was to assess the outcome of bone grafting using a corticocancellous block of iliac crest to reconstruct the support for the deformed, volume-deficient alar base in treated patients with unilateral cleft lip and palate (UCLP). The main outcome being measured was nasal symmetry. Design: This was a prospective study using a noninvasive three-dimensional stereophotogrammetry system (C3D) to assess the position of the alar base. Images were captured immediately preoperatively and at 6 months following the augmentation of the alar base with a block of bone graft. These images were used to calculate facial symmetry scores and were compared using a two sample Students t test to assess the efficacy of the surgical method in reducing facial/nasal asymmetry. Patients: This investigation was conducted on 18 patients with one patient failing to attend for follow-up. The results for 17 patients are presented. Results: Facial symmetry scores improved significantly following the insertion of the bone graft at the deficient alar base (p = 0.005). Conclusions: 3D stereophotogrammetry is a noninvasive, accurate, and archiveable method of assessing facial form and surgical change. Nasal symmetry can be quantified and measured reliably with this tool. Bone grafting to the alar base region of treated UCLP patients with volume deficiency produces improvement in nasal symmetry.

Subjective versus objective assessment of breast reconstruction

BACKGROUND To date breast assessment has been conducted mainly subjectively. However lately validated objective three-dimensional (3D) imaging was developed. The study aimed to assess breast reconstruction subjectively and objectively and conduct a comparison. METHODS In forty-four patients after immediate unilateral breast reconstruction with solely the extended latissimus dorsi flap the breast was captured by validated 3D imaging method and standardized 2D photography. Breast symmetry was subjectively evaluated by six experts who applied the Harris score giving a mark of 1-4 for a poor to excellent result. An error study was conducted by examination of the intra and inter-observer agreement and agreement on controls. By Procrustes analysis an objective asymmetry score was obtained and compared to the subjective assessment. RESULTS The subjective assessment showed that the inter-observer agreement was good or substantial (p-value: <0.0001). There was moderate agreement on the controls (p-value: <0.0001) and fair (p-values: 0.159, 0.134, 0.099) to substantial (p-value: 0.005) intra-observer agreement. The objective assessment revealed that the reconstructed breast showed a significantly smaller volume compared to the opposite side and that the average asymmetry score was 0.052, ranging from 0.019 to 0.136. When comparing the subjective and objective method the relationship between the two scores was highly significant. CONCLUSION Subjective breast assessment lacked accuracy and reproducibility. This was the first error study of subjective breast assessment versus an objective validated 3D imaging method based on true 3D parameters. The substantial agreement between established subjective breast assessment and new validated objective method supported the value of the later and we expect its future role to expand.

Objective evaluation of the latissimus dorsi flap for breast reconstruction using three-dimensional imaging

BACKGROUND The latissimus dorsi muscle flap is a common method for the reconstruction of the breast following mastectomy. The study aimed to assess the quality of this reconstruction using a three-dimensional (3D) imaging method. The null hypothesis was that there was no difference in volume between the reconstructed breast and the opposite side. METHODS This study was conducted in forty-four patients who had had immediate unilateral breast reconstruction by latissimus dorsi muscle flap. The breast was captured using the 3D imaging system. Ten landmarks were digitised on the 3D images. The volume of each breast was measured by the application of Breast Analysis Tool software. The symmetry of the breast was measured using Procrustes analysis. The impact of breast position, orientation, size and intrinsic shape on the overall breast asymmetry was investigated. RESULTS The null hypothesis was rejected. The reconstructed breast showed a significantly smaller volume when compared to the opposite side, p < 0.0001, a mean difference of 176.8 cc and 95% CI (103.5, 250.0). The shape and the position of the reconstructed breast were the main contributing factors to the measured asymmetry score. CONCLUSIONS 3D imaging was efficient in evaluating the outcome of breast surgery. The latissimus dorsi muscle flap on its own for breast reconstruction did not restore the volume and shape of the breast fully lost due to complete mastectomy. The modification of this method and the selection of other or additional surgical techniques for breast reconstruction should be considered. The asymmetry analysis through reflection and Procrustes matching was a useful method for the objective shape analysis of the female breast and presented a new approach for breast shape assessment. The intrinsic breast shape and the positioning of the breast were major components of postoperative breast asymmetry. The reconstructed breast was smaller overall than the un-operated breast at a significant level when assessing the breast volume using the surface area. 3D imaging by multiple stereophotogrammetry was a useful tool for volume measurements, shape analysis and the evaluation of symmetry.

Three-Dimensional Assessment of Early Surgical Outcome in Repaired Unilateral Cleft Lip and Palate: Part 1. Nasal Changes

Objective To evaluate three-dimensional nasal morphology following primary reconstruction in children with unilateral cleft lip and palate relative to contemporaneous noncleft data. Design Prospective, cross-sectional, controlled study. Setting Glasgow Dental Hospital and School, Faculty of Medicine, Glasgow University. Patients and Participants Two groups of 3-year-old children (21 with unilateral cleft lip and palate and 96 controls) with facial images taken using a three-dimensional, vision-based capture technique. Method Three-dimensional images of the face were reflected so the cleft was on the left side to create a homogeneous group for statistical analysis. Three-dimensional coordinates of anthropometric landmarks were extracted from facial images by a single operator. A set of linear measurements was used to compare cleft and control subjects on right and left sides, adjusting for sex differences. Results The mean nasal base width and the width of the nostril floor on right and left sides differed significantly between control and unilateral cleft lip and palate groups. The measurements were greater in children with unilateral cleft lip and palate. The differences in the mean nasal height and mean nasal projection between the groups were not statistically significant. Mean columellar lengths were different between the left and right sides in children with unilateral cleft lip and palate. Conclusions There were significant nasal deformities following the surgical repair of unilateral cleft lip and palate.

The importance of the pose in three-dimensional imaging of the ptotic breast

INTRODUCTION 3D imaging of the breast has recently emerged as a new method for objective breast assessment. However in the ptotic breast shape, which is seen in the majority of cases, the sub-mammary fold remains obscured when the breast is captured in an upright body posture. METHOD A self-designed positioning frame for 3D breast capture was utilized as a safe positioning aide. Six volunteers stood on an adjustable standing step, leaning with the hips against a soft-coated hip roll while stretching forward with the upper body extending to a nearly horizontal position and reaching with the arms forward resting on arm pads. 3D breast capture was conducted simultaneously with eight digital cameras that were positioned to capture the right, left, anterior and inferior views of the breast. Capture was repeated three times at different time intervals. The reproducibility of the pose, captures and 3D measurements were investigated. RESULTS The custom-made positioning frame allowed the complete capture of the breast, even in the ptotic shapes. The investigation of the reproducibility revealed a 6.25% standard deviation of the pose; this being the variable with the smallest variation compared with the variations obtained for reproducibility of captures and 3D measurements. The difference between the first and second pose was not significant at 95% CI (-77.3; 11.9), p = 0.119. CONCLUSION The presented system used a self-designed positioning frame, by which the complete capture of the ptotic breast in near horizontal upper body posture was achieved. Reproducibility of the pose for 3D capture was satisfactory.