Generation and Detection of Cranial Landmark

Purpose : When a surgeon examines the morphology of skull of patient, locations of craniometric landmarks of 3D computed tomography(CT) volume are one of the most important information for surgical purpose. The locations of craniometric landmarks can be found manually by surgeon from the 3D rendered volume or 2D sagittal, axial, and coronal slices which are taken by CT. Since there are many landmarks on the skull, finding these manually is time-consuming, exhaustive, and occasionally inexact. These inefficiencies raise a demand for a automatic localization technique for craniometric landmark points. So in this paper, we propose a novel method through which we can automatically find these landmark points, which are useful for surgical purpose. Materials and Methods : At first, we align the experimental data (CT volumes) using Frankfurt Horizontal Plane (FHP) and Mid Sagittal Plane(MSP) which are defined by 3 and 2 cranial landmark points each. The target landmark of our experiment is the anterior nasal spine. Prior to constructing a statistical cubic model which would be used for detecting the location of the landmark from a given CT volume, reference points for the anterior nasal spine were manually chosen by a surgeon from several CT volume sets. The statistical cubic model is constructed by calculating weighted intensity means of these CT sets around the reference points. By finding the location where similarity function (squared difference function) has the minimal value with this model, the location of the landmark can be found from any given CT volume. Results : In this paper, we used 5 CT volumes to construct the statistical cubic model. The 20 CT volumes including the volumes, which were used to construct the model, were used for testing. The range of age of subjects is up to 2 years (24 months) old. The found points of each data are almost close to the reference point which were manually chosen by surgeon. Also it has been seen that the similarity function always has the global minimum at the detection point. Conclusion : Through the experiment, we have seen the proposed method shows the outstanding performance in searching the landmark point. This algorithm would make surgeons efficiently work with morphological informations of skull. We also expect the potential of our algorithm for searching the anatomic landmarks not only cranial landmarks.ope

Challenges in measuring angles between craniofacial structures

Objective: Three-dimensional (3D) angular measurements between craniofacial planes pose challenges to quantify maxillary and mandibular skeletal discrepancies in surgical treatment planning. This study aims to compare the reproducibility and reliability of two modules to measure angles between planes or lines in 3D virtual surface models. Methodology: Twenty oriented 3D virtual surface models de-identified and constructed from CBCT scans were randomly selected. Three observers placed landmarks and oriented planes to determine angular measurements of pitch, roll and yaw using (1) 3D pre-existing planes, (2) 3D planes created from landmarks and (3) lines created from landmarks. Inter- and intra-observer reproducibility and repeatability were examined using the Intra-Class Correlation (ICC) test. One observer repeated the measurements with an interval of 15 days. ANOVA was applied to compare the 3 methods. Results: The three methods tested provided statistically similar, reproducible and reliable angular measurements of the facial structures. A strong ICC varying from 0.92 to 1.00 was found for the intra-observer agreement. The inter-observer ICC varied from 0.84 to 1.00. Conclusion: Measurements of 3D angles between facial planes in a common coordinate system are reproducible and repeatable either using 3D pre-existing planes, created based on landmarks or angles between lines created from landmarks

3D skull models: a new craniometric approach

Mestrado em Sistemas de InformaçãoEsta dissertação apresenta uma nova abordagem para realizar análises craniométricas com base em modelos 3D de crânios. Atualmente o procedimento usado pelos antropólogos assenta no recurso a craniometria tradicional, i.e. medições manuais, o que implica variados problemas tais como dificuldade em assegurar repetibilidade das medições, erros na mesmas e possível dano nos crânios inerente ao seu manuseamento. A abordagem proposta passa por fazer a aquisição dos crânios recorrendo a um scanner 3D de luz estruturada (realizada por terceiros) e posterior análise recorrendo a uma aplicação especificamente desenvolvida para tal, e na qual assenta o trabalho descrito neste documento. Vários métodos serão abordados, tais como análise de malhas 3D, estudos de normais e curvaturas, obtenção de pontos de interesse e respectivas medidas e, por fim, serão apresentadas conclusões sobre o trabalho, bem como sugestões de trabalho futuro.This dissertation presents a new approach to conduct craniometric analysis based on 3D models of skulls. Nowadays procedures used by anthropologists are based in traditional methods, i.e. manual measurements, which may imply a set of problems such as difficulty in ensuring repeatability of the measurements, measurement errors and can skull damage inherent to the handling. The new approach lies on the acquisition of the skulls using a structured 3D light scanner (done by a third party entity) and subsequent analysis using an application specifically designed for that purpose. Is on the latter that this work is based. Several methods are going to be addressed, such as analysis of 3D meshes, studies of normal vectors and curvatures, obtainment of points of interest (landmark points) and measurements. Finally, conclusions about the developed methods, results and future work

The Development And Application Of A Statistical Shape Model Of The Human Craniofacial Skeleton

Biomechanical investigations involving the characterization of biomaterials or improvement of implant design often employ finite element (FE) analysis. However, the contemporary method of developing a FE mesh from computed tomography scans involves much manual intervention and can be a tedious process. Researchers will often focus their efforts on creating a single highly validated FE model at the expense of incorporating variability of anatomical geometry and material properties, thus limiting the applicability of their findings. The goal of this thesis was to address this issue through the use of a statistical shape model (SSM). A SSM is a probabilistic description of the variation in the shape of a given class of object. (Additional scalar data, such as an elastic constant, can also be incorporated into the model.) By discretizing a sample (i.e. training set) of unique objects of the same class using a set of corresponding nodes, the main modes of shape variation within that shape class are discovered via principal component analysis. By combining the principal components using different linear combinations, new shape instances are created, each with its own unique geometry while retaining the characteristics of its shape class. In this thesis, FE models of the human craniofacial skeleton (CFS) were first validated to establish their viability. A mesh morphing procedure was then developed to map one mesh onto the geometry of 22 other CFS models forming a training set for a SSM of the CFS. After verifying that FE results derived from morphed meshes were no different from those obtained using meshes created with contemporary methods, a SSM of the human CFS was created, and 1000 CFS FE meshes produced. It was found that these meshes accurately described the geometric variation in human population, and were used in a Monte Carlo analysis of facial fracture, finding past studies attempting to characterize the fracture probability of the zygomatic bone are overly conservative

Measures and detection of morphology for craniometry using 3D models

Mestrado em Engenharia de Computadores e TelemáticaThis dissertation focuses on improving the application CraMs, Craniometric Measurements, and exploring new methods of measuring and detecting morphological characteristics for craniometric analysis using 3D models. CraMs was developed in the academic year of 2012-2013 in the scope of a Master dissertation with the objective of aiding anthropologists in the process of per-forming craniometric measurements. Using 3D models and marking points of interest, the anthropologists; are able to obtain craniometric measures in a software application. Using this method helps with the preservation of the specimens and might reduce the variability in measures obtained by different specialists. The work developed in this dissertation includes solving issues found by the domain experts in the application, extending its functionalities to comprise more measures and improve user experience, as well as exploring new methods. These methods focus on morphology analysis of the specimens and on the detection of morphological characteristics, namely the shape of orbits and the complexity of sutures.Esta dissertação tem como objetivos principais melhorar a aplicação CraMs, Craniometric Measurements, e explorar novos métodos de medição e deteção de características morfológicas para análise craniométrica usando modelos 3D. A aplicação CraMs foi desenvolvida no ano letivo 2012-2013 no âmbito de uma dissertação de Mestrado com o objetivo de auxiliar os antropólogos no processo de realizar medições craniométricas. Através da utilização de mode-los 3D e da marcação de pontos de interesse, pelos antropólogos, as medições craniométricas podem ser feitas numa aplicação de software. Este método ajuda a preservação dos espécimes e poderá reduzir a variabilidade entre medidas obtidas por diferentes especialistas. O trabalho desenvolvido nesta dissertação inclui a resolução de problemas encontrados pelos especialistas na aplicação CraMs, a deteção de mais medidas, a melhoria da experiência de utilização, bem como a exploração de novos métodos. Estes novos métodos focam-se na análise da morfologia dos espécimes e na deteção de características morfológicas, nomeadamente a forma das órbitas e a complexidade das suturas

Contributions to the three-dimensional virtual treatment planning of orthognathic surgery

Orientadores: José Mario De Martino, Luis Augusto PasseriTese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia Elétrica e de ComputaçãoResumo: A tecnologia mais recente à disposição da Cirurgia Ortognática possibilita que o diagnóstico e o planejamento do tratamento das deformidades dentofaciais sejam realizados sob uma representação virtual tridimensional (3D) da cabeça do paciente. Com o propósito de contribuir para o aperfeiçoamento desta tecnologia, o trabalho apresentado nesta tese identificou e tratou quatro problemas. A primeira contribuição consistiu na verificação da validade da hipótese de que a mudança de definição do plano horizontal de Frankfort não produz diferenças de medição clinicamente relevantes quando sob indivíduos cujos crânios são consideravelmente simétricos. Os resultados da análise realizada no contexto deste tese indicam que, ao contrário do que se presumia, a hipótese é falsa. A segunda contribuição consistiu na extensão do método de análise cefalométrica de McNamara para que ele pudesse produzir valores 3D. Ao contrário de outros métodos de análise cefalométrica 3D, a extensão criada produz valores verdadeiramente 3D, não perde as informações do método original e preserva as definições geométricas originais das linhas e planos cefalométricos. A terceira contribuição consistiu a) no estabelecimento de normas cefalométricas para brasileiros adultos de ascendência europeia, a partir de imagens de tomografia computadorizada de feixe cônico, que produz uma imagem craniofacial mais precisa e confiável do que a telerradiografia; e b) na avaliação de dimorfismo sexual, para a identificação de características anatômicas diferenciadas entre homens e mulheres desta população. A quarta e última contribuição consistiu na automatização da principal etapa da tecnologia em questão, na qual o cirurgião executa o reposicionamento dos segmentos ósseos maxilares no crânio. O método criado é capaz de corrigir automaticamente os problemas dentofaciais mais comuns tratados pela Cirurgia Ortognática, que envolvem maloclusão esquelética, assimetria facial e discrepância de maxilares. Todas as contribuições deste trabalho foram publicadas em periódicos internacionais do campo da Odontologia e afinsAbstract: The latest technology available for orthognathic surgery allows the diagnosis and treatment planning of dentofacial deformities based on a three-dimensional (3D) virtual representation of the patient's head. In order to contribute to the improvement of this technology, the work presented in this thesis identified and treated four problems. The first contribution consisted in testing the validity of the hypothesis that changing the definition of the Frankfort horizontal plane does not produce clinically relevant measurement differences for subjects whose skulls are considerably symmetrical. The results of the analysis performed in this thesis indicate that, contrary to what was presumed, the hypothesis is false. The second contribution is an extension of the McNamara's method of cephalometric analysis to produce 3D values. Unlike other methods of 3D cephalometric analysis, the extension produces true 3D values, does not lose information captured by the original method, and preserves the original geometric definitions of the cephalometric lines and planes. The third contribution consisted in a) establishing cephalometric norms for Brazilian adults of European descent, based on images from cone-beam computed tomography, which produce a more accurate and reliable craniofacial image than cephalometric radiography; and b) evaluating sexual dimorphism, for the identification of distinct anatomic features between males and females of this population. The fourth contribution consisted in automating the main stage of the technology in question, in which the surgeon performs the positioning of jaw bone segments in the skull. The created method is able to automatically correct the most common dentofacial problems treated by orthognathic surgery, which involves skeletal malocclusion, facial asymmetry, and jaw discrepancy. The contributions of this work were published in international journals of the field of Dentistry and relatedDoutoradoEngenharia de ComputaçãoDoutor em Engenharia ElétricaCAPE

Design of Novel Experiments and Analyses for Head and Spine Trauma Biomechanics

Previous biomechanics research studies have used both whole-body and isolated postmortem human surrogate experiments to define human injury tolerances, advance safety in injury producing environments, and promulgate standards for design of injury mitigating systems. Recent developments in transportation and sports-related fields have led to an increasing need to determine tolerances for combined loading (multi-axis) scenarios. This dissertation demonstrates the efficacy of the novel experimental design and analysis to head and spine trauma in these modalities. The first topic was the design of a novel experiment to examine the effect oblique loading on the tension tolerance of the lumbar spine. To examine this injury tolerance, isolated lumbosacral spine experiments were used with a custom six degree-of-freedom spinal alignment device. The isolated experiment injury matched previous whole-body tests and failure kinetics were obtained. The second topic was the design of a novel experiment to measure the response of the head and neck to off axis moment loading at the occipital condyle joint. A dynamic rotational system applied angular displacement centered at the OC joint in an orientation that resulted in combined flexion-extension/lateral-bending/and axial rotation of the head. Region-specific anatomic kinetics were determined using load cells and a motion capture system. The third topic was the design of a novel experiment model to assess the accuracy of wearable sensors for concussion research. The goal of this topic was to design a new technique which placed a custom sensor near the head-center-of-gravity in whole-body and isolated head/head-neck PMHS. Tests were conducted to benchmark current wearable sensors in the sport and military environments. The measured head kinematics from the in-PMHS sensor serves as the gold standard for these tests. The fourth topic was design of a novel technique to compute three-dimensional time-varying global response kinematics of the head, spine, and pelvis in oblique frontal impacts. Collected data were combined to create three-dimensional temporal global kinematic corridors which are needed to validate current and future finite element models of the components/subsystems, human body models, and they can also be used for benchmarking different computational models

Comparison of the Accuracy of Hexagon Imaging Software versus Digital and Hand Tracings of Lateral Cephalograms

Objectives The aim of this study was to evaluate the validity and reliability of a newly designed cephalometric analysis program (Hexagon software) in comparison with manual and digital (Dolphin software) tracings. Methods Pre-treatment lateral cephalometric radiographs of 32 adult patients between 18 to 41 years (10 males and 22 females, mean age of 22.78 ± 5.17 years) were randomly chosen. For each radiograph, 10 angular and 6 linear measurements were calculated using three different methods (manual and digital using two different software programs). The cephalograms were manually traced using acetate paper, x-ray light box, 0.3 mm HB pencil, ruler, and protractor. For digital tracing, cephalograms were traced with Dolphin vertion-10 (USA) and Hexagon (Iran) software programs. All the analyses were performed by one operator 2 times with at least a four-week interval between the two tracings. The intra-class correlation coefficient (ICC) was used to evaluate the intra-examiner agreement, while the differences between the methods were analyzed using paired t-test, and ANOVA. Results The intra-examiner repeatability of all measurements in all three tracing methods showed high agreement. Differences in measurements between the two software programs and hand tracing were not statistically significant for any of the cephalometric parameters (P>0.05). Conclusion The results demonstrated that the accuracy of cephalometric tracing by the Hexagon software was similar to the Dolphin software, and the manual tracing technique

Análise automática de características não métricas de crânios baseada em modelos 3D

Mestrado em Engenharia de Computadores e TelemáticaO propósito desta dissertação é a melhoria da aplicação CraMs e a análise craniométrica de modelos 3D através da quantificação e classificação de estruturas e características morfológicas. Uma oportunidade para o desenvolvimento deste projeto apresentou-se no ano de 2012 numa tentativa de colaboração com antropólogos, para criar uma aplicação que os ajudasse e facilitasse a realização de medições craniométricas e no processo de marcação de pontos. A aplicação permite ultrapassar alguns dos problemas existentes com os métodos manuais utilizados pelos antropólogos que podem criar resultados irregulares em medições e danificar os espécimes no seu manuseamento. Esta ideia levou ao desenvolvimento de um programa de computador, CraMs, no âmbito de duas dissertações de mestrado nos anos letivos de 2012-2014. Esta nova abordagem baseia-se na aquisição de modelos craniométricos usando um scanner 3D que depois, serão usados para fazer medições e análises normalizadas. O trabalho desenvolvido foca-se na abordagem dos problemas identificados pelos especialistas e na expansão das funcionalidades existentes a fim de criar novos métodos e melhorar a sua usabilidade. Os métodos acima mencionados centram-se na análise da morfologia das amostras e na extração das estruturas de forma uniforme, nomeadamente, a forma da abertura nasal, a depressão pós-bregmática, a espinha nasal anterior e a forma craniana para uma classificação padrão, com o objetivo de identificar a ascendência do indivíduo e o seu género.The purpose of this dissertation work is to improve the CraMs application and the craniometric analysis of 3D models through the quantification and classification of structures and morphological characteristics. An opportunity for the development of this project presented itself in the year of 2012 in a collaboration with anthropologists, to create an application that would assist those performing craniometric measurements and in the process of marking points. The use of an application can improve some of the problems that exist with the manual methods used by anthropologists, that can create irregular results in measurements and can damage the specimens, while handling them. This idea led to the development of a computer application, CraMs, in the scope of two Master dissertations in the academic years 2012-2014. This new approach relies on the acquisition of craniums using a 3D scanner which will, afterwards, be used to make standardized measurements and analysis. The work developed concentrate in the issues identified by the specialists and in the expansion of the functionalities in order to create new methods and improve the usability. The methods mentioned above focus on the morphology analysis of the specimens and on extraction of the structures uniformly, namely the nasal aperture width, the anterior nasal spine, the postbregmatic depression and the cranial shape, for a standard classification with the purpose of identifying the individual ancestry and gender