NUOVE TECNOLOGIE NELL¿AMBITO DELL¿ANTROPOLOGIA FISICA E FORENSE:IMAGING E MODELLAZIONE 3D

Aim of this study is the investigation of the potentialities and limits of the new 3D technologies to be used for documentation, archiving and imaging in the context of Physical and Forensic Anthropology. The widest possible variety of anthropological material was digitally acquired: from skeletal remains into an archaeological site, skeletal elements acquired in the laboratory, to living subjects. The most effective "techniques" for the acquisition of different types of materials were studied and the limits of the scan based on the intrinsic characteristics of the material acquired and the type of instrument used were checked. The Laser Scanner technology has proved to be the most suitable and fast for the acquisition of Skull and Mandible on which to conduct studies about biological profile and identification. The 3D models acquired using Laser Scanner have been used to test a technique of craniofacial Superimposition. The results show that the use of the 3D model of the skull facilitates the process of superimposition; the persistence of a high percentage of false positives indicates that this technique should not be used to identify, it could rather be utilized to exclude. The models of the skull and mandible acquired with 3D laser scanners have been tested as a base to conduct facial reconstructions in the virtual environment. The facial reconstructions performed by two inter-operators were compared using a colorimetric map that has detected good homogeneity in morphometric terms in specific regions of the face but also discrepancies partly due to the different locations of some landmarks made by the two operators, partly due to the shortage of landmarks. New CT technologies generation were also tested: the possibility of age determination from dental volumes was studied with the cone-beam CT technology. Through the use of free software it has been possible to obtain the necessary volumes to calculate the relationship between the volume of the pulp and the volume of its corresponding tooth and carry out the study of the regression. The coefficient of correlation and determination found are comparable to those conducted by other authors using the most expensive equipment; the equation obtained still shows, however, lack of precision of the estimation age. A study that shows that the use of CBCT technology can improve the investigation of morphological stab wounds on cancellous bones was conducted. Conversely metric analysis of the lesions seems not to be very reliable. The acquisition of stab wound with pQCT technology was conducted in a real case: a 3D model was created, in order to allow the operator to define the volume of the lack of tissues related to the lesion. The application of pQCT scan proved to be a potentially useful tool for assessment of bone trauma. As regards the antemortem injury, the CBCT technology was used in the evaluation of the internal structure of the callus. The results could lay the foundation for new perspectives on bone callus evaluation and aging with cone-beam CT technique. In conclusion this study has showed and tested the various applications of 3D technologies in Physical and Forensic Anthropology, defining their limits and in awareness of the importance of the irreplaceable critical judgment of the operator

Personal identification of living people and corpses: usefulness and reliability of intraoral scanners and 3D technologies in modern forensic dentistry

Teeth and oral structures are considered valuable alternatives to DNA analysis and fingerprints for personal identification. Even if their reliability has been recognized, they’ve not been widely or at all tested with new technologies. This project had the aim to study the superimposability of dental and oral structures in radiographic examinations and 3D scans and stability of some of them, like palatal rugae, in patients undergoing to dental procedures and cadavers. The survey has been performed on the virtual and plastic reconstruction of the oral cavities developed from data collected from an innovative intraoral scanner and from orthopantomographs (in all patients and cadavers- if available -) and from full-mouth periapical films (in periodontal patients and cadavers only). In all the patients oral cavity scans started at the beginning of the therapeutic procedures and after one year. In cadavers oral cavity scans have been recorded on the first and the seventh or tenth day from the time of death, allowing a complete survey on how long the palatal rugae features and other oral structures remain stable after corruption of the body sets in their intraoral scans have been then superimposed on radiographs. Morphometric data collected from all the virtual and plastic reconstructions and radiographs, have been listed in an electronic paper. The statistical analysis estimated the differences in shape and length of palatal rugae and dental and other intraoral features in the groups. The results confirm the reliability and the superimposability of 2D radiographs with the reconstructions derived from 3D scans as tools for personal identification, allowing to develop a new protocol for personal identification overcomes the so traditional and so invasive oral autopsy

Characterization of normal facial features and their association with genes

ABSTRACT Background: Craniofacial morphology has been reported to be highly heritable, but little is known about which genetic variants influence normal facial variation in the general population. Aim: To identify facial variation and explore phenotype-genotype associations in a 15-year-old population (2514 females and 2233 males). Subjects and Methods: The subjects involved in this study were recruited from the Avon Longitudinal Study of Parents and Children (ALSPAC). Three-dimensional (3D) facial images were obtained for each subject using two high-resolution Konica Minolta laser scanners. Twenty-one reproducible facial soft tissue landmarks and one constructed mid-endocanthion point (men) were identified and their coordinates were recorded. The 3D facial images were registered using Procrustes analysis (with and without scaling). Principal Component Analysis (PCA) was then employed to identify independent groups ‘principal components, PCs’ of correlated landmark coordinates that represent key facial features contributing to normal facial variation. A novel surface-based method of facial averaging was employed to visualize facial variation. Facial parameters (distances, angles, and ratios) were also generated using facial landmarks. Sex prediction based on facial parameters was explored using discriminant function analysis. A discovery-phase genome-wide association analysis (GWAS) was carried out for 2,185 ALSPAC subjects and replication was undertaken in a further 1,622 ALSPAC individuals. Results: 14 (unscaled) and 17 (scaled) PCs were identified explaining 82% of the total variance in facial form and shape. 250 facial parameters were derived (90 distances, 118 angles, 42 ratios). 24 facial parameters were found to provide sex prediction efficiency of over 70%, 23 of these parameters are distances that describe variation in face height, nose width, and prominence of various facial structures. 54 distances associated with previous reported high heritability and the 14 (unscaled) PCs were included in the discovery-phase GWAS. Four genetic associations with the distances were identified in the discovery analysis, and one of these, the association between the common ‘intronic’ SNP (rs7559271) in PAX3 gene on chromosome (2) and the nasion to mid-endocanthion 3D distance (n-men) was replicated strongly (p = 4 x 10-7). PAX3 gene encodes a transcription factor that plays crucial role in fetal development including craniofacial bones. PAX3 contains two DNA-binding domains, a paired-box domain and a homeodomain. The protein made from PAX3 gene directs the activity of other genes that signal neural crest cells to form specialized tissues such as craniofacial bones. PAX3 different mutations may lead to non-functional PAX3 polypeptides and destroy the ability of the PAX3 proteins to bind to DNA and regulate the activity of other genes to form bones and other specific tissues. Conclusions: The variation in facial form and shape can be accurately quantified and visualized as a multidimensional statistical continuum with respect to the principal components. The derived PCs may be useful to identify and classify faces according to a scale of normality. A strong genetic association was identified between the common SNP (rs7559271) in PAX3 gene on chromosome (2) and the nasion to mid-endocanthion 3D distance (n-men). Variation in this distance leads to nasal bridge prominence

Three-dimensional assessment of dentofacial deformity in children with clefts

Background: Changes in clinical management; advances in non-invasive three-dimensional imaging; developments in methods of shape analysis. Aim: To assess three-dimensional dentofacial deformity with a view to early appraisal of primary surgical outcome. Results: Significant differences in upper lip morphology were found between the cleft children and their unaffected peers; nasal asymmetry that became more obvious in function was noted in cleft children; the maxillary dental arches of the children with repaired cleft palate were shallow, short and narrow; and the dental arch, deformity and the facial soft tissue deformity were unrelated. Contributions to the field: It has been shown that deviation from normal could be detected as young as 3 years of age using computerised stereophotogrammetry; preliminary, objective, three-dimensional analysis of facial function has been completed in young children; the accuracy of three-dimensional CT scanning of dentate study models and the time cost of data collection were quantified; and this study has produced a body of three-dimensional data that can test and support analytical advances

Three-dimensional breast assessment by multiple stereophotogrammetry after breast reconstruction with latissimus dorsi flap

Introduction: Numerous methods exist for the assessment of the female breast. Traditionally, a subjective approach was taken for surgical planning and evaluation of the postoperative outcome. Several objective methods have been developed to support this procedure, among which are laser scanning, MRI, mammography, ultrasound and photography. Recently, 3D imaging technology has been developed. Material & Method: 3D breast assessment by multiple stereophotogrammetry was examined. A custom-made imaging system with eight digital cameras arranged in four camera pods was utilised. This system was used for breast capture, resulting in eight images obtained by the cameras. The merging of these images and 3D image construction was carried out by C3D software and the volume assessment of the 3D images was made using breast analysis tool (BAT) software, developed by Glasgow University. A validation study was conducted. Nine plaster models were investigated and their volume determined by 3D stereophotogrammetry and water displacement method. Water displacement was considered to be the gold standard for comparison. The plaster models were specially made in order to represent a variety of shapes and sizes of the female breast. Each plaster model was examined 10 times by each method. Further, the volumes of the breasts of six female volunteer live models were investigated by the same two methods and the results compared. A special focus was placed on the reproducibility of the assessment. Each live model was captured with the 3D capture system three times at two different time points after retaking a special pose in a custom-made positioning frame. Altogether, each live model was captured six times, resulting in six 3D images, each of which was measured three times with BAT software. A patient study was conducted in 44 patients after unilateral immediate breast reconstruction with Latissimus dorsi flap and no contra-lateral surgery. Each patient underwent 3D imaging with the multiple stereophotogrammetry system. During capture, the special pose in the custom-made positioning frame was taken by the patient’s leaning forward almost horizontally with the upper body for the breasts to rise off the chest wall to enable full breast coverage by the cameras. 3D images were constructed with C3D software and volumes measured with BAT. For each patient, one 3D image was constructed and measured four times with BAT software. In addition to the volume determination, a shape analysis was conducted. For this purpose, 10 landmarks were determined according to recommendations in the literature. Two landmarks, sternal notch and xiphoid, were marked, forming an imaginary midline between each other and four landmarks on each breast, i.e. the medial and lateral ends of the infra-mammary fold, and the most prominent and most inferior breast points were utilised for symmetry assessment between the right and left breasts. Each landmark was recorded four times by the operator on the 3D image and three-dimensional coordinates obtained. By assessment of the left and right breasts a breast asymmetry score was calculated. Firstly, breast asymmetry was assessed objectively on the 3D images through the centroid size, which was determined as the square root of the sum of squared Euclidian distances from each landmark to the centroid. The centroid was the geometric mean of the landmarks. Secondly, asymmetry was assessed through breast volume by application of BAT software. Thirdly, asymmetry was examined through the landmarks themselves by investigation of the mismatch of the landmark configuration of one breast and its relabelled and matched reflection. The non-operated and reconstructed sides were compared and landmarks were recorded by the operator in three dimensions in four repeated tests. A decomposition of the total landmark asymmetry into its factors was conducted by fixation of the surface of the non-operated side and translation, rotation and scaling of the surface of the reconstructed side. For comparison, a subjective breast assessment was conducted by six expert observers who rated the results after breast reconstruction by subjective qualitative assessment of the symmetry in 2D images of the same 44 patients in six poses. For this purpose the Harris scale was utilised, providing a score of 1 to 4 for poor to excellent symmetry. Results: The results revealed that differences in the obtained volumes in the plaster models were not significant. In contrast, differences in the breast volumes measured in the live models were significant. The examination of the reproducibility revealed that overall reproducibility obtained by stereophotogrammetry was better than that obtained by water displacement. No correlation between breast size and reproducibility of the measurements was found. The results of the patient study demonstrated that the reproducibility of the landmarks was within 5 mm. There was a non-significant difference of the centroid sizes between both breasts. There was a significant difference of the volumes between the two breasts, with the non-operated side being larger than the reconstructed side. Volume was considered to be a more accurate measure for comparison of both breasts than centroid size as it was based on thousands of data points for the calculation as opposed to only four points of the centroid size. The statistical analysis of the landmark data provided a mathematical formula for determination of the breast asymmetry score. The average asymmetry score, derived by landmark assessment as the degree of mismatch between both sides, was 0.052 with scores ranging from 0.019 (lowest score) to 0.136 (highest score). The decomposition of the landmark-based asymmetry revealed that location was the most important factor contributing to breast asymmetry, ahead of intrinsic breast asymmetry, orientation and scale. When investigating the subjective assessment, the inter-observer agreement was good or substantial. There was moderate agreement on the controls and fair to substantial intra-observer agreement. When comparing the objective and subjective assessments, it was found that the relationship between the two scores was highly significant. Conclusion: We concluded that 3D breast assessment by multiple stereophotogrammetry was reliable for a comparative analysis and provided objective data to breast volume, shape and symmetry. A breast asymmetry score was developed, enabling an objective measurement of breast asymmetry after breast reconstruction. 3D breast assessment served as an objective method for comparison to subjective breast assessment

Forensic facial reconstruction using 3-D computer graphics: evaluation and improvement of its reliability in identification

This thesis is concerned with computerised forensic 3-D facial reconstruction as a means of identification and involves the restoration of the face on the skull in an attempt to achieve a close likeness of the individual when alive. The reconstruction process begins with the biological identification of the skeletal remains, (age, sex, ancestry and build). Facial reconstruction is then carried out and essentially works by building the “face” up from the skull using soft tissue thicknesses at specific locations from existing data. However, it is used as a last resort on skeletonised, badly decomposed or mutilated corpses, when no other information is available; even then it is only accepted as corroborative evidence in court. It is performed in the hope that it may stimulate recognition, and consequently narrow the field of identification, allowing other tests to be carried out, such as radiographic and/or dental comparisons, DNA analysis or other means, to establish positive identification. The advantages of the computerised method over the manual clay reconstruction are speed, rapid editing capability, production of images that can be stored and reconstructions repeated at any time if required. Furthermore, in many cases, the original skull instead of a cast or model may be used for reconstruction because the 3-D computerised procedure is rapid and non invasive. However, the most significant advantage of this technique with regard to the aims and objectives of the thesis is that a number of alternative reconstructions may be produced sequentially for the same skull by using different facial templates from the database that meet the anthropological/biological criteria of the skull. The issues addressed by the study and therefore its main aims are: a) evaluation and b) improvement of the reliability of facial reconstruction using 3-D computer graphics. The methodology involved initially digitizing a skull using a low-power laser scanner and a video camera interfaced to a computer. From a database of previously scanned faces, ten facial templates were selected that matched the anthropological criteria of each of the skulls, i.e. age, sex, ancestry and build. Landmarks with their corresponding soft tissue thicknesses were then located and placed on the skull and the equivalent ones on the face. The 3-D computer graphics then reconstructed the face by morphing (warping) the facial template over the skull by matching the corresponding landmarks on the skull and face with the appropriate soft tissue thicknesses at those landmark locations. The soft tissue thicknesses used at their specific landmark locations also matched the anthropological criteria of the skulls, since soft tissue depths are dependent on age, sex, ancestry and build. One of the major problems with any reconstruction which affect its reliability for identification is the uncertainty of the shape of some of the individual characteristics of soft tissue structures such as shape of lips, ears and nose/nasal tip since there is not direct information on the skull regarding the shape of some of these features. In addition, with the laser scanning system, the faces within the database all have closed eyes, because of the potential laser hazard to the eyes. Thus it is necessary to add “opened” eyes, head and facial hair (where appropriate) to give a realistic appearance to the face. The software provides the facility to export a 2-D view in a TIFF or JPEG format from the 3-D reconstructed image. The file can then be imported into a police identi-kit system such as E-FIT™, which allows the addition of features. In this study five skulls of known individuals were used for reconstruction in the manner explained. Ten facial templates which fulfilled the anthropological criteria (age, sex, ancestry and build) for each skull were used for the rebuilding process, thus totalling fifty reconstructions. The study employed a psychological resemblance test (experiment 1) where 20 different assessors, were asked to select in each case study, the best three matches of the ten reconstructions with the ante-mortem photograph of the individual during life. The results from these tests were correlated with a mathematical shape analysis assessment using Procrustes Analysis in which, the skull was compared in turn with each of the ten facial templates of each case study (experiment 2).The ranking of the assessors’ reconstruction choice was correlated with the ranking of the Procrustes Analysis by using Spearman’s Rank Order Correlation. The results indicate that although not statistically significant, it would seem however, that in some of the case studies, the mathematical approach using Procrustes Analysis does seems to capture some perceptual similarity in human observers. Experiment 3, similar to experiment 1, was a further psychological resemblance test, which involved implementing E-Fit features on four of the ten reconstructed images per case study. Assessors were asked to select the closest E-Fit image match with the ante-mortem photograph. Again, results indicated that, although not statistically significant, adding E-Fit feature to the images appears to improve perceptual similarity in human observers, provided, the limitations of adding these characteristics are addressed. Furthermore, there also appears to be good agreement in most of the case studies between the two psychological resemblance tests using the two different sets of assessors in experiment 1 and 3 (reconstruction choice and E-Fit choice, respectively). Further work involving anthropometric comparisons and using two methods of assessment (landmark line matching between images and proportion indices) was also carried out (experiment 4). It was found that matching landmark lines between images appeared to be only of limited value due to the images not being aligned at exactly the same viewpoint and magnification. It should be appreciated that because the thesis was based on recognition and was not an anthropometric study, precise alignment of viewpoints was not a requirement. Hence using the same data from the study, although images were in the frontal view, they were not aligned to the accuracy acceptable for an anthropometric study as there was no requirement to so. It would appear that, although there was some correspondence between the discrepant distances and the first and second ranked reconstructions, no firm conclusions could be drawn from this technique and therefore does not assist in understanding the way observers made their choices. Further tests would need to be carried out (beyond the scope of the thesis) to reach any firm conclusions. Undoubtedly, given the complex nature of the recognition process, it would have been desirable to use reconstructions of persons known to the assessors rather than asking them to assess unfamiliar persons, since it is well established that familiar faces are easier to recognize than those that are unfamiliar to observers. It should be appreciated however, that, although the study was designed in this way for practical and ethical reasons, it nevertheless does not truly reflect the real operational forensic scenario. Furthermore, recognition/matching is a much more complex process and even a reconstructed face which may be generally morphologically similar to the person in life may not capture perceptual similarity in human observers, especially in an unfamiliar scenario. It is not certain that identification will always occur even when the facial reconstruction bears good resemblance to the target individual

Three dimensional study to quantify the relationship between facial hard and soft tissue movement as a result of orthognathic surgery

Introduction Prediction of soft tissue changes following orthognathic surgery has been frequently attempted in the past decades. It has gradually progressed from the classic “cut and paste” of photographs to the computer assisted 2D surgical prediction planning; and finally, comprehensive 3D surgical planning was introduced to help surgeons and patients to decide on the magnitude and direction of surgical movements as well as the type of surgery to be considered for the correction of facial dysmorphology. A wealth of experience was gained and numerous published literature is available which has augmented the knowledge of facial soft tissue behaviour and helped to improve the ability to closely simulate facial changes following orthognathic surgery. This was particularly noticed following the introduction of the three dimensional imaging into the medical research and clinical applications. Several approaches have been considered to mathematically predict soft tissue changes in three dimensions, following orthognathic surgery. The most common are the Finite element model and Mass tensor Model. These were developed into software packages which are currently used in clinical practice. In general, these methods produce an acceptable level of prediction accuracy of soft tissue changes following orthognathic surgery. Studies, however, have shown a limited prediction accuracy at specific regions of the face, in particular the areas around the lips. Aims The aim of this project is to conduct a comprehensive assessment of hard and soft tissue changes following orthognathic surgery and introduce a new method for prediction of facial soft tissue changes.   Methodology The study was carried out on the pre- and post-operative CBCT images of 100 patients who received their orthognathic surgery treatment at Glasgow dental hospital and school, Glasgow, UK. Three groups of patients were included in the analysis; patients who underwent Le Fort I maxillary advancement surgery; bilateral sagittal split mandibular advancement surgery or bimaxillary advancement surgery. A generic facial mesh was used to standardise the information obtained from individual patient’s facial image and Principal component analysis (PCA) was applied to interpolate the correlations between the skeletal surgical displacement and the resultant soft tissue changes. The identified relationship between hard tissue and soft tissue was then applied on a new set of preoperative 3D facial images and the predicted results were compared to the actual surgical changes measured from their post-operative 3D facial images. A set of validation studies was conducted. To include: • Comparison between voxel based registration and surface registration to analyse changes following orthognathic surgery. The results showed there was no statistically significant difference between the two methods. Voxel based registration, however, showed more reliability as it preserved the link between the soft tissue and skeletal structures of the face during the image registration process. Accordingly, voxel based registration was the method of choice for superimposition of the pre- and post-operative images. The result of this study was published in a refereed journal. • Direct DICOM slice landmarking; a novel technique to quantify the direction and magnitude of skeletal surgical movements. This method represents a new approach to quantify maxillary and mandibular surgical displacement in three dimensions. The technique includes measuring the distance of corresponding landmarks digitized directly on DICOM image slices in relation to three dimensional reference planes. The accuracy of the measurements was assessed against a set of “gold standard” measurements extracted from simulated model surgery. The results confirmed the accuracy of the method within 0.34mm. Therefore, the method was applied in this study. The results of this validation were published in a peer refereed journal. • The use of a generic mesh to assess soft tissue changes using stereophotogrammetry. The generic facial mesh played a major role in the soft tissue dense correspondence analysis. The conformed generic mesh represented the geometrical information of the individual’s facial mesh on which it was conformed (elastically deformed). Therefore, the accuracy of generic mesh conformation is essential to guarantee an accurate replica of the individual facial characteristics. The results showed an acceptable overall mean error of the conformation of generic mesh 1 mm. The results of this study were accepted for publication in peer refereed scientific journal. Skeletal tissue analysis was performed using the validated “Direct DICOM slices landmarking method” while soft tissue analysis was performed using Dense correspondence analysis. The analysis of soft tissue was novel and produced a comprehensive description of facial changes in response to orthognathic surgery. The results were accepted for publication in a refereed scientific Journal. The main soft tissue changes associated with Le Fort I were advancement at the midface region combined with widening of the paranasal, upper lip and nostrils. Minor changes were noticed at the tip of the nose and oral commissures. The main soft tissue changes associated with mandibular advancement surgery were advancement and downward displacement of the chin and lower lip regions, limited widening of the lower lip and slight reversion of the lower lip vermilion combined with minimal backward displacement of the upper lip were recorded. Minimal changes were observed on the oral commissures. The main soft tissue changes associated with bimaxillary advancement surgery were generalized advancement of the middle and lower thirds of the face combined with widening of the paranasal, upper lip and nostrils regions. In Le Fort I cases, the correlation between the changes of the facial soft tissue and the skeletal surgical movements was assessed using PCA. A statistical method known as ’Leave one out cross validation’ was applied on the 30 cases which had Le Fort I osteotomy surgical procedure to effectively utilize the data for the prediction algorithm. The prediction accuracy of soft tissue changes showed a mean error ranging between (0.0006mm±0.582) at the nose region to (-0.0316mm±2.1996) at the various facial regions