Dissertations / Theses on the topic '3D soft tissue prediction'

The purpose of this study is to find the design tool to create a soft tissue 3D model able to be used for finite element analysis to simulate the facial soft tissue deformation under g-loading and the helmet and mask/tissue interaction. Such a model will be of value in the design of new helmets and oxygen mask system, to reduce the effects of inertia, to provide improved fit, to minimise oxygen leakage especially when deformed under high g-loading. This work is concerned with the creation of a 3D geometric model. Further work may involve the measurement of mechanical properties of the facial soft tissue, finite element analysis and validation of the model. Using high frequency A-scan ultrasound allows the superficial tissue to be measured on volunteers without risk. The investigation covers 112 points on half of the face, linked to 11 defined morphological zones. The zonal boundaries are based on previous research and are initially identified by inspection and palpation of the face. There is large thickness range difference (30%) over the face in most zones defined in an individual. The iso-thickness zone hypothesis is not valid if the 'constant' thickness criterion is set to be 10% for all zones. Software algorithm for automatically detecting the facial soft tissue thickness is developed and validated to be effective (5% fail rate). Thickness data is acquired from European white males, females and Chinese males. The data collected in this study is also useful in forensic science for facial reconstruction purpose. Laser scanning method has been used to obtain the facial surface profile to create a surface model into which the soft tissue layer thickness distribution around the face can be incorporated. The surface model is exported in IGES format and can be imported in CAD software. Electromagnetic space locating method is used to acquire the ultrasound probe position so as to find the position of the tissue thickness. Point-based registration method is used to integrate the ultrasound thickness data into the laser scanned surface model to create a soft tissue shell solid model. The model is exported in IGES data format so that it can be imported into a finite element analysis package for further processing.

A 3D imaging system (C3D®), based on the principles of stereophotogrammetry, has been developed for use in the assessment of facial changes following orthognathic surgery. Patients’ perception of their facial appearance before and after orthognathic surgery has been evaluated using standardised questionnaires, but few studies have tried to link this perception with the underlying two-dimensional cephalometric data. Comparisons between patients’ subjective opinions and 3D objective assessment of facial morphology have not been performed. Aims: (1) To test the reliability of the 3D imaging system; (2) to determine the effect of orthognathic surgery on the 3D soft-tissue morphology; (3) to assess skeletal changes following orthognathic surgery; (4) to evaluate soft-tissue to hard-tissue displacement ratios; (5) to ascertain the impact of orthognathic surgery on patients’ perception of their facial appearance and their psychosocial characteristics, (6) to explore the dentofacial deformity, sex and age on the psychosocial characteristics; (7) to evaluate the extent of compatibility between the cephalometric and the three-dimensional measurements and (8) to determine if the magnitude of facial soft-tissue changes affects the perception of facial changes at six months following surgery. Results and Conclusions: C3D imaging system was proved to be accurate with high reproducibility. The reproducibility of landmark identification on 3D models was high for 24 out of the 34 anthropometric landmarks (SD£0.5 mm). One volumetric algorithm in the Facial Analysis Tool had an acceptable accuracy for the assessment of volumetric changes following orthognathic surgery (mean error=0.314 cm3). The error of cephalometric method was low and the simulation of mandibular closure proved to be reproducible. 2D soft-tissue measurements were compatible with 3D measurements in terms of distances, but angular measurements showed significant differences (p<0.05).

La nécessité de simulations de tissus mous, tels que les organes internes, se pose avec le progrès des domaines scientifiques et médicaux. Le but de ma thèse est de développer un nouveau modèle générique, topologique et physique, pour simuler les organes humains. Un tel modèle doit être facile à utiliser, doit pouvoir effectuer des simulations en temps réel avec un niveau de précision permettant l'utilisation à des fins médicales. Cette thèse explore de nouvelles méthodes de simulation et propose des améliorations pour la modélisation de corps déformables. Les méthodes proposées visent à pouvoir effectuer des simulations rapides, robustes et fournissant des résultats physiquement précis. L'intérêt principal de nos solutions réside dans la simulation de tissus mous élastiques a petites et grandes déformations à des fins médicales. Nous montrons que pour les méthodes existantes, la précision pour simuler librement des corps déformables ne va pas de pair avec la performance en temps de calcul. De plus, pour atteindre l'objectif de simulation rapide, de nombreuses approches déplacent certains calculs dans une étape de pré-traitement, ce qui entraîne l'impossibilité d'effectuer des opérations de modification topologiques au cours de la simulation comme la découpe ou le raffinement. Dans cette thèse, le cadre utilisé pour les simulations s'appelle TopoSim. Il est conçu pour simuler des matériaux à l'aide de systèmes masses-ressorts (MSS) avec des paramètres d'entrée spécifiques. En utilisant un MSS, qui est connu pour sa simplicité et sa capacité à effectuer des simulations temps réel, nous présentons plusieurs améliorations basé physiques pour contrôler les fonctionnalités globales du MSS qui jouent un rôle clé dans la simulation de tissus réels. La première partie de ce travail de thèse vise à reproduire une expérience réelle de simulation physique qui a étudié le comportement du tissu porcin à l'aide d'un rhéomètre rotatif. Son objectif était de modéliser un corps viscoélastique non linéaire. A partir de l'ensemble des données acquises, les auteurs de l'expérience ont dérivé une loi de comportement visco-élastique qui a ensuite été utilisée afin de la comparer avec nos résultats de simulation. Nous définissons une formulation des forces viscoélastiques non linéaires inspirée de la loi de comportement physique. La force elle-même introduit une non linéarité dans le système car elle dépend fortement de l'amplitude de l'allongement du ressort et de trois paramètres spécifiques à chaque type de tissu. La seconde partie de la thèse présente notre travail sur les forces de correction de volume permettant de modéliser correctement les changements volumétriques dans un MSS. Ces forces assurent un comportement isotrope des solides élastiques et un comportement correct du volume quel que soit la valeur du coefficient de Poisson utilisé. La méthode nécessite de résoudre deux problèmes: l'instabilité provoquant des plis et les contraintes de Cauchy. Nos solutions à ces limitations impliquent deux étapes. La première consiste à utiliser trois types de ressorts dans un maillage entièrement hexaédrique: les arêtes, les faces diagonales et les diagonales internes. Les raideurs des ressorts dans le système ont été formulées pour obéir aux lois mécaniques de base. La deuxième étape consiste à ajouter des forces de correction linéaires calculées en fonction du changement de volume et des paramètres mécaniques du tissu simulé, à savoir le coefficient de Poisson et le module de Young [etc…]
The need for simulations of soft tissues, like internal organs, arises with the progress of the scientific and medical environments. The goal of my PhD is to develop a novel generic topological and physical model to simulate human organs. Such a model shall be easy to use, perform the simulations in the real time and which accuracy will allow usage for the medical purposes.This thesis explores novel simulation methods and improvement approaches for modeling deformable bodies. The methods aim at fast and robust simulations with physically accurate results. The main interest lies in simulating elastic soft tissues at small and large strains for medical purposes. We show however, that in the existing methods the accuracyto freely simulate deformable bodies and the real-time performance do not go hand in hand. Additionally, to reach the goal of simulating fast, many of the approaches move the necessary calculations to pre-computational part of the simulation, which results in inability to perform topological operations like cutting or refining.The framework used for simulations in this thesis is designed to simulate materials using Mass Spring Systems (MSS) with particular input parameters. Using Mass-Spring System, which is known for its simplicity and ability to perform fast simulations, we present several physically-based improvements to control global features of MSS which play the key role in simulation of real bodies

The increase of different types of cell cultures, which can be used for the in vitro studies of physiological and/or pathological processes, has introduced the need to improve culture techniques through the use of materials and culture media that promote growth, recreating a cellular micro-environment that can be asserted in in vivo condition. Therefore, it is important to design and develop new biologically sustainable methods, such as to contribute to the “closer-to-in vivo” condition. In particular, the design of a 3D in vitro model of neuronal culture is an important step to better understand the mechanisms of cell-cell communication, synaptogenesis and neurophysiological circuits. In order to mimic the ECM environment, a granular, porous and soft structure is preferred in the design of an artificial neural network. The granular structure is preferred due to the fact that CNS tissue seems to be organized as a greater proportion of the microscale tissue, that can be thought of as granular. For this reason, the thesis is focused on the production and characterization of bipolymeric microbeads as a 3D scaffold for soft tissue engineering. The biopolymer Chitosan is presented as an alternative adhesion factor and support for 2D and 3D neuronal cell cultures. Chitosan is a copolymer of glucosamine and N-acetyl-glucosamine, obtained by the deacetylation of chitin; it is well known for its low-cost, biocompatibility, biodegradability, muco-adhesiveness, antibacterial activity as well as its bioaffinity. Chitosan backbone shows positive charges of primary ammines that favor the electrostatic interactions with the negatively charged cell membranes promoting cell adhesion and growth. The standard studies focoused on the development of nervous system, have been performed using traditional monolayer culture onto supports modified by extracellular matrix components or synthetic biopolymers such as poly-ornithine and poly-lysine which are expressed at stages critical for neuronal differentiation in situ and are functional in neurite outgrowth in vitro, acting as adhesion proteins. Morphological and functional characterization of 2D neuronal culture grew up onto chitosan susbtrates are carried out and compared with the gold standard reported in literature, in order to validate the ability of chitosan to support neuronal adhesion, networks development and the differentiation capacity. 3D cultured neurons on chitosan microbeads based-scaffold, showed a structural development of a functional network that are more representative of the in vivo environment. The studies reported in this thesis, successfully demonstrate the alternative use of the polysaccharide chitosan as adhesion factor and as a structural component for 2D/3D neuronal cultures. Definitely, thanks to its low cost and versatility, it could be easily functionalized for the fabrication of personalized of in vitro models. In this thesis, a new technology to converts monodisperse microbead hydrogels to fine powders, is reported. Microengineered emulsion-to-powder (MEtoP) technology generates microgels with all the molecular, colloidal, and bulk characteristics of fresh microbeas upon resuspension in aqueous media. GelMA microbeads are fabricated by microfluidic technique, that is one of the most effective techniques, and allows precise tuning of the compositions and geometrical characteristics of microbeads. Gelatin-methacryloyl (GelMA) is a semi-synthetic hydrogel which consists of gelatin derivatized with methacrylamide and methacrylate groups. These hydrogels provide cells with an optimal biological environment (e.g., RGD motifs for adhesion) and can be quickly photo-crosslinked, which provide shape fidelity and stability at physiological temperature. MEtoP technology is based on protecting the dispersed phase of an emulsion to preserve its physical and chemical cues during harsh freezing and lyophilization procedures. This technology avoids the persistent problems of colloids, including difficulty in sterilization, bacterial and viral contamination, impaired stability, high processing costs, and difficult packaging and transportation.

Tissue engineering (TE) integrates methods of cells, engineering and materials to improve or replace biological functions of native tissues or organs. 3D printing technologies have been used in TE to produce different kinds of tissues. Based on review of the exiting 3D printing technologies used in TE, special requirements of fabricating soft scaffolds are identified. Soft scaffolds provide a microenvironment with biocompatibility for living cells proliferation. This research focuses on 3D printer design and printing parameters investigation for fabrication of soft scaffolds. A 3D printer is proposed for producing artificial soft scaffolds, with components of a pneumatic dispenser, a temperature controller and a multi-nozzle changing system. Relations of 3D printing parameters are investigated to improve the printing quality of soft scaffolds. It provides guidance for printing customized bio-materials with improved efficiency and quality. In the research, printing parameters are identified and classified based on existing research solutions. A deposition model is established to analyze the parameters relations. Quantitative criteria of parameters are proposed to evaluate the printing quality. A series of experiments including factors experiments and comparison tests are conducted to find effects of parameters and their interactions. A case study is conducted to verify the analytic solution of proposed models. This research confirms that the hydrogel concentration and nozzle diameters have significant effects on the filament diameter. Factor interactions are mainly embodied in between the concentration of hydrogel solutions and dispensing pressures. Besides filament diameters, the nozzle height and space also affect the printing accuracy significantly. An appropriate nozzle height is considered to be 1.4 times than the nozzle diameter, and a reasonable nozzle space is suggested from 2.0 to 2.5 times of the nozzle diameter.

Three-dimensional (3D) printing has become broadly available and can be utilized to customize clamping mechanisms in biomechanical experiments. This report will describe our experience using 3D printed clamps to mount soft tissues from different anatomical regions. The feasibility and potential limitations of the technology will be discussed. Tissues were sourced in a fresh condition, including human skin, ligaments and tendons. Standardized clamps and fixtures were 3D printed and used to mount specimens. In quasi-static tensile tests combined with digital image correlation and fatigue trials we characterized the applicability of the clamping technique. Scanning electron microscopy was utilized to evaluate the specimens to assess the integrity of the extracellular matrix following the mechanical tests. 3D printed clamps showed no signs of clamping-related failure during the quasi-static tests, and intact extracellular matrix was found in the clamping area, at the transition clamping area and the central area from where the strain data was obtained. In the fatigue tests, material slippage was low, allowing for cyclic tests beyond 105 cycles. Comparison to other clamping techniques yields that 3D printed clamps ease and expedite specimen handling, are highly adaptable to specimen geometries and ideal for high-standardization and high-throughput experiments in soft tissue biomechanics.

The numbers of patients needing facial prostheses has increased in the last few decades due to improving cancer survival rates. The many limitations of the handmade prostheses together with rapid expansion of prototyping in all directions, particularly in producing human anatomically accurate parts, have raised the question of how to employ this technology for rapid manufacturing of facial soft tissue prostheses. The idea started to grow and the project was implemented based on CAD/CAM principles – additive manufacturing technology, by employing layered fabrication of facial prostheses from starch powder and a water based binder and infiltrated with a silicone polymer (SPIS). The project aimed to produce a facial prosthesis by using 3D colour printing, which would match the patient’s skin shade and have the desirable mechanical properties, through a relatively low cost process that would be accessible to the global patient community. This was achieved by providing a simple system for data capture, design and reproducible method of manufacture with a clinically acceptable material. The prosthesis produced has several advantages and few limitations when compared to existing products/prostheses made from silicone polymer (SP). The mechanical properties and durability were not as good as those of the SP made prosthesis but they were acceptable, although the ideal properties have yet to be identified. Colour reproduction and colour matching were more than acceptable, although the colour of the SPIS parts was less stable than the SP colour under natural and accelerated weathering conditions. However, it is acknowledged that neither of the two methods used represent the natural life use on patients and the deficiencies demonstrated in terms of mechanical properties and colour instability were partially inherent in the methodology used, as the project was still at the developmental stage and it was not possible to apply real life tests on patients. Moreover, deficiencies in mechanical and optical properties were probably caused by the starch present, which was used as a scaffold for the SP. Furthermore, a suitable retention system utilising existing components was designed and added to the prosthesis. This enabled the prosthesis to be retained by implants with no need for the addition of adhesive. This would also help to prolong the durability and life span of the prosthesis. The capability of the printer to produce skin shades was determined and it was found that all the skin colours measured fall within the range of the 3D colour printer and thereby the printer was able to produce all the colours required. Biocompatibility was also acceptable, with a very low rate of toxicity. However, no material is 100% safe and each material has a certain range of toxicity at certain concentrations. At this stage of the project, it can be confirmed that facial prostheses were successfully manufactured by using 3D colour printing to match the patient’s skin shade, using biocompatible materials and having the desirable mechanical properties. Furthermore, the technology used enabled prostheses to be produced in a shorter time frame and at a lower cost than conventional SP prostheses. They are also very lightweight, easier to use and possibly more comfortable for the patients. Moreover, this technology has the capability of producing multiple prostheses at the time of manufacture at reduced extra cost, whilst the data can be saved and can be utilised/modified for producing further copies in the future without having to going through all the steps involved with handmade prostheses. Based on the mechanical properties and colour measurements the prostheses will have a finite service life and the recommendation is that these prostheses will need replacing every 6 to 12 months, depending on how the patient handles and maintains the prostheses and whether the prosthesis is being used as an interim or definitive prosthesis. This was largely comparable to existing prostheses but without the time and cost implications for replacement. However, it is acknowledged that further investigations and clinical case studies are required to investigate the “real life” effect on the prostheses and to get feedback from the patients in order to make appropriate improvements to the mechanical properties and the durability of the prosthesis.

Thesis (M.S.)--West Virginia University, 2003.
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This thesis describes the acquisition of maxillo-facial soft tissue thickness data and its integration into a Computer Aided Design based solid model of the human head. The final outcome was a significant element in a novel approach to the creation of a 3D modeller for detailed study of the design of protective equipment at the interface with the skin tissues. Anthropometric surface data of 300 head 3D profiles were acquired using a laser scanning system consisting of a dual mirror configuration and a CCD video camera. Approximately 70,000 data points are scanned in less than ten seconds. The resulting surface model has a resolution of +/-0.5mm circumferentially and +/- 0.2mm radially. Soft tissue thickness values have been measured using A-scanning ultrasound system with a pulsed, 12.5MHz focused ultrasound probe with an axial resolution of 0.31mm and a lateral resolution of 2.7mm. The accuracy of the measurements has been estimated as +/-0.25mm. A novel representation of these data has been suggested in which quasi iso-thickness zones have been identified. These zones, where the thickness values are often consistent to within as little as +/-0.5mm, have been shown to be consistent with key anatomical regions. Colour spectral plots visualise the tissue zones. The thickness data are referenced to the laser data using a magnetic spacing system, POLHEMUS by 3DSpaceRTM the resulting 3D soft tissue model has important uses in Finite Element Analysis methods for design of protective equipment.

PGSm was synthesized, and characterized chemically and mechanically. Porous PGSm was photocured into 3D foams. PGSm was printed via microstereolithography into nerve guidance conduits and tested for use in peripheral nerve repair in vitro, ex vivo and in vivo. Porous PGSm conduits were developed and tested ex vivo, with an intended use for larger gap injuries. Porous PGSm was developed into tunable microparticles and explored for use as a cartilage tissue-engineering scaffold. The polyHIPE was also developed as an in vitro neuronal model and a scaffold for ESCs. Results show the material was developed into a photocurable polymer, capable of being 3D printed into highly accurate NGCs. PGSm conduits performed well overall and regeneration into the distal stump was witnessed in vivo. Techniques were developed to photocure reproducible porous polyHIPE conduits, with promising initial in vitro/ex vivo results. Porous microparticles were seen to allow for the development of cartilage like tissue in vitro. Porous PGSm was used for neuronal models and stem cell scaffolds. In summary the developed PGSm is useful for simple and complex scaffolds for soft tissue engineering.

The purpose of this study was to evaluate the influence of facial convexity on the perception of social attributes in a young adult population. Nine models were asked to pose for a 3 dimensional photograph that was then modified to represent ideal, retrognathic, and prognathic facial convexity angles. Survey evaluators were shown digital videos of models with ideal and non-ideal profiles and asked to rate their perception of the following 4 social attributes: intelligence, athleticism, popularity, and leadership ability using a visual analog scale. Results gathered from 271 evaluators showed that the model images with ideal facial convexity angles were rated higher on average than the same model images with retrognathic and prognathic profiles. The differences in ratings between ideal and non-ideal profiles were significant for intelligence (P = 0.0009), athleticism (P = 0.0002), and leadership ability (P = 0.0008). Differences in perceived popularity (P = 0.2169) showed no significant differences among facial convexities.

1.1. ASTRATTO OBIETTIVI: Lo scopo di questa revisione era di esplorare lo sviluppo degli espansori di tessuti molli, i loro diversi tipi e le loro potenziali applicazioni prima dell'innesto osseo e del posizionamento dell'impianto. MATERIALI E METODI: è stata eseguita una revisione della letteratura pertinente utilizzando PubMed per comprendere la dinamica degli espansori dei tessuti molli e determinare la posizione corrente delle loro applicazioni di pre-incremento. RISULTATI: Ci sono informazioni preliminari sui benefici dell'espansione dei tessuti molli pre-allargamento (STE). I risultati non possono essere generalizzati a causa delle dimensioni campionarie relativamente ridotte degli scarsi studi clinici disponibili in letteratura. CONCLUSIONI: Sono necessari ulteriori studi clinici con campioni di dimensioni maggiori e follow-up a lungo termine prima che gli espansori dei tessuti molli possano essere applicati con sicurezza nella pratica clinica quotidiana.2.1. ASTRATTO OBIETTIVI: Indagare sugli esiti clinici, le complicanze e l'aumento di volume dell'espansione dei tessuti molli pre-aumento (STE). MATERIALI E METODI: Espansori tissutali sono stati impiantati in sette pazienti che richiedono l'aumento osseo verticale e / o orizzontale. La rigenerazione ossea guidata (GBR) è stata effettuata dopo 20, 40 o 60 giorni di STE. I guadagni ossei verticali e orizzontali sono stati analizzati con la tomografia computerizzata a fascio conico (CBCT). Per l'analisi volumetrica sono state utilizzate la scansione ottica e la sovrapposizione di modelli di fusione fabbricati da impronte di alginato pre- e post-augmentazione. RISULTATI: sette siti su sette pazienti sono stati trattati con STE. La perforazione si è verificata in due siti; guasto precoce dovuto alla tenuta della sacca preparata, e ritardo in ritardo a causa di piccole fessure del guscio di silicio che coprono l'espansore a seguito della manipolazione del corpo dell'espansore con una pinzetta dentale. Dopo la dilatazione, la chiusura della ferita primaria è stata facilmente ottenuta con l'aumento senza successive esposizioni del trapianto. Sei mesi dopo l'aumento, l'analisi CBCT ha rivelato un guadagno osseo verticale elevato (media = 7,3 ± 1,2 mm). La media del guadagno osseo orizzontale era di 5,5 ± 2,9 mm. L'analisi volumetrica di tre casi di espansione ha rivelato un aumento medio del volume di 483,8 ± 251,7 mm3. L'aumento del volume dei tessuti molli corrispondeva solo all'espansore del cilindro da 0,24 ml (aumento del volume = 259,4 mm3), mentre questo aumento era quasi la metà del volume dell'espansore finale per gli espansori del cilindro da 0,7 e 1,3 ml (rispettivamente 436,1 mm3 e 755,9 mm3). Tutti gli impianti dentali sono stati osteointegrati nei pazienti sottoposti a successiva terapia implantare. CONCLUSIONI: Elevato guadagno osseo verticale e complicanze post-chirurgiche minime sono state associate a procedure di aumento osseo precedute dall'espansione dei tessuti molli (STE).4.1. ASTRATTO OBIETTIVI: Analizzare i pattern di riassorbimento osseo nelle mandibole posteriori e i corrispondenti innesti ossei digitalmente progettati per capire se si presentano in cluster distinti. MATERIALI E METODI: In questa analisi retrospettiva, sono state analizzate 120 scansioni CBCT per valutare la frequenza della classificazione di Cawood e Howell, nelle mandibole posteriori destra e sinistra. I risultati sono stati confrontati tra sesso ed età. La classe atrofica più frequente che ha bisogno di aumento osseo è stata virtualmente rigenerata nei segmenti mandibolari utilizzando un software specifico. Altezza, larghezza e lunghezza degli innesti ottenuti sono stati analizzati per concludere se questi innesti si presentano in cluster distinti. Risultati. La classe V era la classe atrofica più frequente rispetto alla classe IV e VI nelle mandibole posteriori sinistra e destra (16%, 20,8% rispettivamente). Gli stadi atrofici gravi erano più frequenti nelle femmine (p = 0,029 per il lato sinistro, p = 0,007 per il lato destro) e nei gruppi di età più avanzata (p = 0,008 per il lato destro) Dopo la rigenerazione virtuale dei difetti della classe V, tre cluster erano evidente, che differisce solo per la lunghezza, in base al numero di denti mancanti (p = 0,0001). L'altezza e la larghezza degli innesti virtuali erano comparabili per i tre cluster (p> 0,05). Il volume medio dell'innesto virtuale era di 2.184 mm3 (quattro denti mancanti), 1,819 mm3 (tre denti mancanti) e 1,476 mm3 (due denti mancanti). In conclusione, l'atrofia dello stadio V era il pattern di riassorbimento più frequente rispetto alle classi IV e V, nelle mandibole posteriori. La procedura di rigenerazione virtuale ha rivelato tre gruppi di innesti virtuali, che differiscono solo per la lunghezza in base al numero di denti mancanti. Si consigliano studi futuri per determinare il rapporto di adattamento tra innesti virtuali e reali alla superficie dell'osso.
1.1. ABSTRACT OBJECTIVES: The aim of this review was to explore the development of soft tissue expanders, their different types and their potential applications prior to bone augmentation and implant placement. MATERIALS & METHODS: A review of pertinent literature was performed using PubMed to comprehend the dynamics of soft tissue expanders and determine the current position of their pre- augmentation applications. RESULTS: There is promising, albeit preliminary information regarding the benefits of pre- augmentation soft tissue expansion (STE). Findings cannot be generalized due to relatively small sample size of the scarce clinical studies available in literature. CONCLUSIONS: Further clinical trials with larger sample sizes and long-term follow-up are needed before soft tissue expanders can be confidently applied in everyday clinical practice. 2.1. ABSTRACT OBJECTIVES: To investigate the clinical outcomes, complications and volume gain of pre-augmentation soft tissue expansion (STE). MATERIALS & METHODS: Tissue expanders were implanted in seven patients requiring vertical and/or horizontal bone augmentation. Guided bone regeneration (GBR) was carried out either after 20, 40 or 60 days of STE. Vertical and horizontal bone gains were analyzed with cone beam computed tomography (CBCT) scans. Optic scanning and superimposition of cast models fabricated from pre- and post- augmentation alginate impressions were used for volumetric analysis. RESULTS: Seven sites in seven patients were treated with STE. Perforation occurred in two sites; early failure due to the tightness of the prepared pouch, and late failure due to minor cracks of the silicon shell covering the expander as a result of handling of the expander body with a dental tweezer. Post-expansion, primary wound closure was easily achieved at augmentation without any subsequent graft expositions. Six months post-augmentation, CBCT analysis revealed high vertical bone gain (mean = 7.3 ± 1.2 mm). Mean of horizontal bone gain was 5.5 ± 2.9 mm. Volumetric analysis of three successful expansion cases revealed a mean volume increase of 483.8 ± 251.7 mm3. Soft tissue volume increase corresponded only to the 0.24 ml cylinder expander (volume increase = 259.4 mm3), while this increase was almost half of the final expander volume for the 0.7 and 1.3 ml cylinder expanders (436.1 mm3 & 755.9 mm3 respectively). Volumetric analysis of the late expansion failure reflected soft tissue shrinkage, which might suggest that STE affects tissues by tension and does not cause real volume gain. All dental implants were osseointegrated in the patients that underwent subsequent dental implant therapy. CONCLUSIONS: High vertical bone gain and minimal post-surgical complications were associated with bone augmentation procedures preceded by soft tissue expansion (STE). 3.1. ABSTRACT To ensure a successful dental implant therapy, presence of adequate vertical and horizontal alveolar bone is fundamental. However, an insufficient amount of alveolar ridge in both dimensions is often encountered in dental practice due to the consequences of oral diseases and tooth loss. Although post-extraction socket preservation has been adopted to lessen the need for such invasive approaches, it utilizes bone-grafting materials, which have limitations that could negatively affect the quality of bone formation. To overcome the drawbacks of routinely employed grafting materials, bone-graft substitutes such as 3D-scaffolds have been recently investigated in the dental field. In this review, we highlight different biomaterials suitable for 3D-scaffold fabrication, with a focus on “3D-printed” ones as bone graft substitutes that might be convenient for various applications related to implant therapy. We also briefly discuss their possible adoption for periodontal regeneration. 4.1. ABSTRACT OBJECTIVES: To analyze bone resorption patterns in the posterior mandibles and their corresponding digitally designed bone grafts to understand if they come in distinct clusters. MATERIALS & METHODS: In this retrospective analysis, 120 CBCT scans were analyzed to evaluate the frequency of Cawood & Howell classification, in right and left posterior mandibles. Results were compared between gender and age. The most frequent atrophic class that needs bone augmentation was virtually regenerated in the mandibular segments using specific software. Height, width and length of the obtained grafts were analyzed to conclude if these grafts come in distinct clusters. RESULTS: Class V was the most frequent atrophic class in comparison to class IV & VI in the left and right posterior mandibles (16%, 20.8% respectively). Severe atrophic stages were more frequent in females (p= 0.029 for the left side, p= 0.007 for the right side) and in older age groups (p= 0.008 for the right side) After virtual regeneration of class V defects, three clusters were evident, differing only in length, based on the number of missing teeth (p= 0.0001). Height and width of the virtual grafts were comparable for the three clusters (p > 0.05). Mean virtual graft volume was 2,184 mm3 (four missing teeth), 1,819 mm3 (three missing teeth) & 1,476 mm3 (two missing teeth). CONCLUSIONS: Stage V atrophy was the most frequent resorption pattern in comparison to classes IV & V, in posterior mandibles. Virtual regeneration procedure revealed three clusters of virtual grafts, differing only in the length based on the number of missing teeth. Future studies are recommended to determine the adaptation ratio between virtual and actual grafts to bone surface.

The purpose of this work is to study phenotypic craniofacial traits of unaffected parents of individuals with nonsyndromic cleft lip with or without palate (NSCL/P). In order to evaluate these craniofacial traits, three dimensional photographs were obtained and landmarked to compare the sample of unaffected parents with a control sample. The sample was comprised of 40 unaffected fathers, 25 control males, 84 unaffected mothers, and 34 control females. Twenty-four three-dimensional landmarks were exported for analysis for each subject. For the purposes of this study, nine euclidean distances were subjected to a discriminant function analysis to evaluate their ability to discriminate between an unaffected parent and a control. In both the male and female analysis, certain craniofacial measurements correctly and significantly discriminated between unaffected parents and controls. It appears that certain facial traits are subclinical markers for enhanced genetic susceptibility to nonsyndromic cleft lip with or without palate.

Soft-tissue sarcoma (STS) of the extremities forms a relatively uncommon yet aggressive group of neoplasms with high metastatic risk of the disease. The vast majority of STS metastases occur in the lungs. Due to the general poor prognosis of patients diagnosed with STS lung metastases, there is a clinical need to identify relevant prognostic factors as early as possible in the course of staging and treatment management. Recent evidence suggests that positron emission tomography (PET) using fluorodeoxyglucose (FDG) and magnetic resonance (MR) imaging texture features have the potential to predict the outcome of tumours through the assessment of their microenvironment heterogeneity characteristics. The goal of this work is therefore to investigate FDG-PET and MR texture features as potential early predictors of lung metastasis risk in STS cancer of the extremities.In this study, a dataset of 35 patients with histologically proven STS of the extremities was retrospectively analyzed. All patients received pre-treatment FDG-PET and MR scans. MR imaging data comprised of T1-weighted, T2 fat-saturation (T2FS) and short tau inversion recovery (STIR) sequences. The median follow-up period was 29 months (range: 4 to 85 months). Thirteen patients from the dataset developed lung metastases. Six texture features from the gray-level co-occurrence matrix (GLCM) were extracted from the FDG-PET, MR and fused FDG-PET/MR scans. In addition, the maximum standard uptake value (SUVmax) of the tumours was included in the feature set. The fusion of FDG-PET and MR scans was carried out using the discrete wavelet transform (DWT) and a band-pass frequencies enhancement technique. Statistical analysis was performed using Spearman's correlation (rho), and multivariable modeling using logistic regression. The prediction performance of the different multivariable models was assessed using bootstrap resampling by calculating the area under the receiver-operating characteristics curve (AUC) and Matthews' correlation coefficient (MCC). The highest univariate prediction of lung metastases was attributed to the SUVmax metric (rho=0.6382, p<0.0001). Most texture features extracted from fused scans had higher Spearman's correlation with lung metastases than those extracted from separate scans. On separate scans, FDG-PET texture features were generally dominant over MR texture features. The highest multivariable prediction of lung metastases was found using fused scans and the following 4-parameters model: 0.94*SUVmax − 0.401*PET-T2FS/STIR--Variance − 6.7*PET-T1--Contrast − 165*PET-T1--Homogeneity + 140. This model reached rho=0.8255, p<0.0001 on the entire dataset and AUC=0.956±0.002, MCC=0.829±0.002 in bootstrap testing sets. Overall, this work indicates the strong potential of FDG-PET and MR texture features for the prediction of lung metastases in STS cancer of the extremities. Substantial prediction improvements were found using texture features from fused scans and multivariable modeling strategies compared to texture features extracted from separate scans and univariate analysis. Potentially, this could improve patient outcomes by allowing better personalization of treatments and the application of pre-emptive strategies to mitigate disease spread.
Les sarcomes des tissus mous (STM) provenant des extrémités forment un groupe relativement rare de néoplasme avec un risque métastatique élevé. La grande majorité des métastases provenant des STM ont lieu dans les poumons, et le pronostique résultant est généralement faible. En ce sens, il est important d'identifier autant de facteurs pronostiques pertinents que possible au moment du diagnostique et de la gestion du traitement. Certains travaux récents ont permis de démontrer que les caractéristiques texturales d'images provenant de la tomographie par émission de positrons (TEP) utilisant le fluorodéoxyglucose (FDG) et l'imagerie par résonance magnétique (IRM) ont le potentiel de prédire l'évolution tumorale grâce à l'évaluation des propriétés d'hétérogénéité biologique des tumeurs. Donc, le but de ce travail est d'évaluer le potentiel des caractéristiques texturales d'images FDG-TEP et IRM en tant que prédicteur du risque de métastases aux poumons pour le cancer des STM provenant des extrémités. Dans cette étude, une cohorte de 35 patients diagnostiqués avec des STM aux extrémités a été rétrospectivement analysée. Tous les patients ont reçu un scan FDG-TEP et un scan IRM avant leur traitement. Les séquences IRM qui ont été utilisés dans l'analyse sont: T1, T2 par saturation des gras (T2FS) et STIR. Les patients ont été suivis sur une période médiane de 29 mois (intervalle: 4 à 85 mois). Treize patients de la cohorte ont développé des métastases aux poumons. Six caractéristiques texturales d'images provenant de la matrice de co-occurrence des niveaux de gris (GLCM) ont été extraites des scans FDG-PET, IRM et FDG-PET/IRM fusionnés. De plus, la valeur maximale de consommation standard des tumeurs (SUVmax) a été incluse dans l'analyse. La fusion des scans a été effectuée grâce à la transformée d'ondelettes discrètes et grâce à une technique de renforcement des fréquences passe-bandes. L'analyse statistique a été effectuée en utilisant la corrélation de Spearman (rho), et l'analyse multivariable en utilisant la régression logistique. Les performances de prédiction des différents modèles multivariables ont été évaluées en calculant 2 métriques à partir de la technique de ré-échantillonnage « bootstrap »: L'aire sous la courbe de fonctionnement (AUC) et le coefficient de corrélation de Matthews (MCC). La plus haute prédiction univariée est attribuée à SUVmax (rho=0.6382, p<0.0001). La plupart des caractéristiques texturales extraites des scans fusionnés possèdent des coefficients de corrélation Spearman plus haut que celles extraites des scans séparés. Dans le cas des scans séparés, les caractéristiques texturales provenant de FDG-TEP sont généralement dominantes par rapport à celles provenant des scans IRM. La plus haute prédiction multivariable est provenue des scans fusionnés avec le model suivant: 0.94*SUVmax − 0.401*PET-T2FS/STIR--Variance − 6.7*PET-T1--Contrast − 165*PET-T1--Homogeneity + 140. Ce model a atteint des résultats de rho=0.8255, p<0.0001 sur l'ensemble des patients et AUC=0.956±0.002, MCC=0.829±0.002 sur les ensembles de tests « bootstrap ». De façon générale, cette étude indique le fort potentiel des caractéristiques texturales provenant des images FDG-TEP et IRM pour prédire les métastases aux poumons dans le cas des patients atteints des STM aux extrémités. Une amélioration substantielle des prédictions a pu être obtenue en utilisant les caractéristiques texturales des scans fusionnés et des stratégies d'analyse multivariable comparativement aux caractéristiques texturales des scans séparés et à l'analyse univariée. Potentiellement, cela pourrait mener à l'application de stratégies préventives pour atténuer la propagation du cancer des STM et à l'application de traitements mieux adaptés aux besoins des patients.

The aim of this study is to verify the soft tissues changes in the nasolabial area after Le Fort I osteotomy using a cone-beam computed tomography (CBCT) evaluation of three- dimensional (3D) volume surfaces in preoperative, early postoperative (1 month) and late postoperative (1 year) periods. Many authors have described the undesired soft tissue changes following the Le Fort I osteotomy, as well as many different techniques to prevent and control these changes. However, few studies have attempted to perform a 3D analysis of the nasolabial complex. The subsequent lack of standardized measuring method hinder the performance of comparisons among studies. By doing a systematic review of the literature in this topic, our objective is to list the main adverse effects associated to Le Fort I osteotomy and to list the most effective available techniques of alar dimension control. A specific technique of alar cinch suture will be described and further analyzed whether it is effective or not in controlling alar base widening. To this effect, a clinical retrospective research will be performed in 80 patients who have undergone a Le Fort I osteotomy and received the aforementioned alar cinch suture technique. All patients were operated by the same surgeon (FHA) at Instituto Maxilofacial – Teknon Medical Center - Barcelona. All the data regarding the selected patients will be anonymized, analyzed and measured by the same observer (APSG) and supervised by the same investigator (RGM). The CBCT volumes of these patients will be superimposed and measured in three different periods of treatment using the Dolphin® Orthognathic Surgery Planning software. A specific protocol to superimpose the 3D images using the Voxel Based Registration (VBR) is going to be developed and validated. At the Instituto Maxilofacial, CBCT acquisition is part of the routine diagnostic protocol of every patient undergoing orthognathic procedures. The study can be performed without modifications in this protocol.

La reconstitution faciale a pour but de restituer le visage d’un individu à partir de la morphologie de son crâne. Cette technique est utilisée en anthropologie médico-légale pour apporter de nouveaux témoignages dans l’identification de restes humains. Les objectifs de thèse sont d’établir une base de données crânio-faciale 3D de Français grâce à l’imagerie médicale, de tester les règles traditionnelles de reconstitution, et de quantifier les corrélations morphologiques entre tissus osseux et cutanés. Des examens hospitaliers par scanner tomodensitométrique (18 – 96 ans ; sexe ratio 1,16:1) ont été traités avec le logiciel TIVMI pour reconstruire avec précision les surfaces osseuses et cutanées. Plus de 200 points de repère ont pu être positionnés sur 500 individus, en suivant un protocole précis (répétabilité et reproductibilité vérifiées). L’extraction de distances Euclidiennes a permis de tester plusieurs règles traditionnelles, et d’étudier la spécificité et la variabilité des épaisseurs de tissus mous. Parallèlement, les coordonnées 3D des points ont été analysées par morphométrie géométrique. Les covariations entre groupes de points osseux et cutanés ont pu être quantifiées, ainsi que les asymétries, allométries, et influences de l’âge et du sexe sur les variations de conformation. Ces résultats ont permis l’élaboration d’une méthode d’estimation de la position des points de repère du visage, et la création (en collaboration avec le LaBRI) d’un module de reconstitution faciale nommé AFA3D. Basé sur le principe de déformation d’un visage synthétique, ce logiciel restitue la forme la plus probable du visage en fonction de la position de 78 points crâniométriques
Facial approximation aims at the production of a face based on the skull morphology. This technique is performed in forensic anthropology to bring new testimonies in cases of human remains identification. The goals of this research are to establish a database of French skulls and faces in 3D through medical imaging, to test traditional guidelines, and to quantify the morphological correlations between soft and hard tissues. Computed tomography exams, collected in French hospitals (18 – 96 years; sex ratio 1.16:1), were treated with TIVMI software to reconstruct accurately the bone and skin surfaces. More than 200 landmarks have been placed on 500 subjects, following a protocol which repeatability and reproducibility have been checked. The extraction of Euclidian distances allowed testing traditional guidelines, and studying specificity and variability of soft tissue depths. In parallel, the 3D coordinates were analyzed with geometric morphometrics. Covariations between groups of bone landmarks and groups of skin landmarks were quantified, along with asymmetry, allometry, and influences of age and sex on the shape changes. These results allowed for the creation of a method to estimate the position of skin landmarks, and for the development of a facial approximation module in TIVMI, called AFA3D (in collaboration with the LaBRI). Based on the warping of a synthetic face, this software renders the most probable face depending on the position of 78 cranial landmarks

碩士
長庚大學
資訊工程研究所
95
It is always desired for the patients to foresee the result of their own craniofacial surgeries, whether the operation is necessary (due to facial deform, etc.) or for aesthetic purpose. Post-treatment prediction of soft tissue has been the most challenging task in that the correlation between the soft- and hard-tissues may be altered. A semi-automatic process to characterize correspondence of the pre- and post-surgery and visualized assistance for the physician are thus in dire need. In this work, we propose a soft-tissue prediction and reconstruction procedure of the plastic facial surgery includes (1) analysis of craniofacial images, (2) identify the characteristics of the soft tissues, such as fat, skin, etc., and hard tissues, such as bones, (3) reconstruction the projected facial images with treated hard tissues covered with corresponding soft tissues, and finally (4) visualization of the three-dimensional facial model. We developed an interactive and dynamic system that the physician can follow the procedure or create his or her own surgical planning scheme.

This retrospective cohort study investigated the effects of rapid maxillary expansion on the soft tissues using CBCTs. The sample consisted of 60 subjects: experimental group (n=30, treated with rapid maxillary expansion (RME), age:10.93 ± 2.20) and control group (n=30, age 11.43 ± 2.8). Soft tissue measurements were made using soft tissue landmarks. Paired t-test was used to compare the changes after expansion, and student t-test was used to compare the experimental and the control group. Intraclass correlation coefficient was used to evaluate intra-examiner reliability. Statistically significant differences were noted when comparing the experimental to the control group in transverse and anterior posterior dimensions. Increase was noted at the bialar distance (0.90mm, p=0.0363), nostril medium left to midsagittal plane (0.75mm, p=0.0423), the angle of pronasale to nostril base right and left (1.640, p<.001), columella width (0.56mm, p=0.0272), nostril base left to midsagittal plane, (1.03mm, p=0.0207), chelion right to endocanthus right (1.57mm, p=0.0086), chelion left to endocanthus left (1.96mm, p=0.0015). Anteroposteriorly, the tip of the nose moved forward (pronasale to coronal plane (1.97mm, p=0.0018), nostril medium right to coronal plane (1.07mm, p=0.0486), alare right to coronal plane (1.67mm, p=0.0117), pronasale to nostril base left (2.24mm, p<0.001) and right (2.12mm, p<0.001). Finally comparing genders, all the measurements were significantly greater in males compared to females except for columella width. In conclusion, RME influences soft tissue changes of the face, specifically in the nasal area. The base of the nose, bialar distance and columella widened while the tip of the nose moved forward.

碩士
中原大學
電機工程研究所
92
Respiratory motion results in an added uncertainty in the radiation treatment of thoracic malignancies due to an increase in the normal tissue irradiated and an uncertainty in the radiation coverage of the tumor. This results in a potential increase in complications from treatment and may be insufficient to ensure coverage of the tumor. Reduction of the volume of normal tissue irradiation while maintaining tumor coverage is used to accomplish this goal. The application of 4D CT imaging to radiotherapy treatment planning is an active area of research with the goal to reduce the required normal tissue irradiation and improve the tumor coverage. In order to achieve adequate coverage of the tumor with a tumoricidal radiation dose a margin of normal tissue is also irradiated to high dose. With optical flow method the image content properties are utilized to generate a displacement vector between each voxel in the reference image to the target image for registration. In this study we develop and validate 3D optical flow method to measure intra-thoracic tumor motion from inspiration/expiration breath-hold CT image sets. Two important tools used in this study for validations are the 4D NCAT and 3D TPS, a computer generated phantom that simulates a thorax with both respiratory and cardiac motion and the elastic movement calculation.

碩士
國立臺灣大學
臨床牙醫學研究所
106
Objective: The purpose of this study is to evaluate facial asymmetry 3 dimensionally using cone-beam computed tomography (CBCT) in skeletal Class III patients. Material and methods: The patients were classified into 3 groups based on the relationship of direction and amount of menton deviation relative to the transverse ramus width asymmetry. In groups 1 and 2, menton deviation was accompanied by a larger transverse ramus distance on the deviated side. While in group 1 the amount of menton deviation was greater than that of ramus asymmetry, group 2 patients showed a smaller menton deviation in comparison to ramus asymmetry. Patients in group 3 exhibited an atypical asymmetry of larger ramus distance contralateral to the side of menton deviation. Statistical analysis was run to compare hard/ soft tissue characteristics between the deviation side and non-deviation side in each group. Difference of the structural characteristics among 3 groups were also delineated by using one-way ANOVA and posy-hoc tests. Results: Group 1 showed the greatest amount of menton deviation. Significant greater transverse dimension of maxilla and mandible were noted for the deviation side. In addition, maxilla exhibited downward canting in the non-deviation side, and the ramus of the deviation side was more buccal inclined than that of the non-deviation side. The bucco-lingual axes of maxillary first molars were compensated to transverse skeletal asymmetry, which resulted in canting in the maxillary occlusal plane. In contrast, no significant difference in soft tissue thickness between the deviation side and the non-deviation side was observed. Group 2 showed the lowest amount of menton deviation. Significant greater transverse dimension of maxilla and mandible were observed at the deviation side. No significant difference was noted in the bucco-lingual tooth axis of bilateral maxillary first molars nor dentoalveolar heights was observed between the deviated and non-deviated sides. There was no significant difference in soft tissue thickness between the deviation and non-deviation sides. In group 3, the Jugular point was more anterior positioned in the non-deviation side than the deviation side. The transverse dimension of mandible was significant greater at the non-deviation side. The asymmetry in bucco-lingual inclination of bilateral maxillary first molars was not statistically significant, suggesting that no obvious dental compensation existed. However, the soft tissue thickness was significant greater at the deviation side. The Jugular-C measurement was significant different between the 3 groups. In group 1 and 3, the Jugular point was more anteriorly positioned at the non-deviated side than the deviation side. Most of the measurements representing mandibular structures were significant different among 3 groups. Similarly, in group 1 and 3, the mandibular foramen and mental foramen were more anteriorly positioned at the non-deviation side. Group 1 exhibited more buccally inclined ramus at the deviation side than the other 2 groups. Group 3 showed the smallest amount of transverse width discrepancy between bilateral ramus. There were significant differences in the measurements of maxilla U6 canting and maxilla U6 dimension difference between 3 groups. Group 1 showed greatest maxilla U6 canting and transverse width discrepancy. All the soft tissue measurements were significant different among the 3 groups. The lip canting was of greatest amount in group 1. Group 3 exhibited the greatest difference in the bilateral soft tissue thickness of the lower face. Conclusion Different structural characteristics were found among 3 groups. In Group 1 patients, the maxillomandibular complex exhibited displacement including a roll rotation in frontal view and a yaw rotation in axial view to the deviation side. As to group 2 patients, facial asymmetry was characterized by mandible sideshift to the deviation side. Abruptly, the maxillomandibular complex of group 3 patients exhibited a yaw rotation to the deviation side.

碩士
長庚大學
顱顏口腔醫學研究所
104
Objective 3D simulated navigation in OGS is a technique that provides support during surgery and provides a bony "guiding splint" to precisely place the bony segments into the planned position. The aim of this study was to analyze the pre- and post-surgical soft-tissue and hard-tissue correlations, ratios, and regressions of patients following our Computer-Aided Three-Dimensional Simulation and Navigation in OGS (CASNOS) procedures. Material/Methods Forty adult patients at Kaohsiung Chang Gung Memorial Hospital, Taiwan (n=40; 11 men, 29 women; age, 23.5±4.9 years) undergoing 2-jaw OGS (maxillary Le Fort I osteotomy and mandible bilateral sagittal split osteotomy) were selected retrospectively after excluding for craniofacial syndromes. Each patient had complete records, including CT imaging data from 3 weeks before surgery to 6 months after surgery. We used two open-source software: ITK-SNAP and 3D-Slicer to analyze 15 landmarks in hard tissue and corresponding soft tissue 3-D movement; then subdivided all 40 cases into two groups: Clockwise/Counter-Clockwise rotation, and Symmetry/Asymmetry to determine the correlations, ratios, and regression between soft-hard-tissue. Results (1) We found a high correlation between 3D skin and bone changes, and especially, AP direction was the most important factor responsible for soft tissue movement in all these three directions. (2) The ratio of 3D skin/bone was as follows: ANS/tip of Nose = 0.54, A/Subnasale = 0.58, Upper lip/Upper central incisor = 0.67, Lower lip/ Lower central incisor =0.76, B/Si =0.93, Pog =0.92, and Me =0.92. (3) We also found that the regression of 3D SOFT TISSUE = a0+a1*BONEAP+ a2*BONEVer.+ a3*BONELat. Conclusion 3D analysis can help predict soft-tissue profile while simulating bony movement. Our study provides 3D quantitative data of OGS planning by using 3D CT simulation and navigation. In the future, we can use 3D surface simulation to actually predict the surgical outcome.

The goal of this research is to achieve accurate characterization of multi-layered soft tissues in three dimensions using focused ultrasound. The characterization of the acoustic parameters of each tissue layer is formulated as recursive processes of forward- and inverse- scattering. Forward scattering deals with the modeling of focused ultrasound wave propagation in multi-layered tissues, and the computation of the focused wave amplitudes in the tissues based on the acoustic parameters of the tissue as generated by inverse scattering. The model for mapping the tissue acoustic parameters to focused waves is highly nonlinear and stochastic. In addition, solving (or inverting) the model to obtain tissue acoustic parameters is an ill-posed problem. Therefore, a nonlinear stochastic inverse scattering method is proposed such that no linearization and mathematical inversion of the model are required. Inverse scattering aims to estimate the tissue acoustic parameters based on the forward scattering model and ultrasound measurements of the tissues. A multi-scale stochastic filter (MSF) is proposed to perform inverse scattering. MSF generates a set of tissue acoustic parameters, which are then mapped into focused wave amplitudes in the multi-layered tissues by forward scattering. The tissue acoustic parameters are weighted by comparing their focused wave amplitudes to the actual ultrasound measurements. The weighted parameters are used to estimate a weighted Gaussian mixture as the posterior probability density function (PDF) of the parameters. This PDF is optimized to achieve minimum estimation error variance in the sense of the posterior Cramer-Rao bound. The optimized posterior PDF is used to produce minimum mean-square-error estimates of the tissue acoustic parameters. As a result, both the estimation error and uncertainty of the parameters are minimized. PDF optimization is formulated based on a novel multi-scale PDF analysis framework. This framework is founded based on exploiting the analogy between PDFs and analog (or digital) signals. PDFs and signals are similar in the sense that they represent characteristics of variables in their respective domains, except that there are constraints imposed on PDFs. Therefore, it is reasonable to consider a PDF as a signal that is subject to amplitude constraints, and as such apply signal processing techniques to analyze the PDF. The multi-scale PDF analysis framework is proposed to recursively decompose an arbitrary PDF from its fine to coarse scales. The recursive decompositions are designed so as to ensure that requirements such as PDF constraints, zero-phase shift and non-creation of artifacts are satisfied. The relationship between the PDFs at consecutive scales is derived in order for the PDF optimization process to recursively reconstruct the posterior PDF from its coarse to fine scales. At each scale, PDF reconstruction aims to reduce the variances of the posterior PDF Gaussian components, and as a result the confidence in the estimate is increased. The overall posterior PDF variance reduction is guided by the posterior Cramer-Rao bound. A series of experiments is conducted to investigate the performance of the proposed method on ultrasound multi-layered soft tissue characterization. Multi-layered tissue phantoms that emulate ocular components of the eye are fabricated as test subjects. Experimental results confirm that the proposed MSF inverse scattering approach is well suited for three-dimensional ultrasound tissue characterization. In addition, performance comparisons between MSF and a state-of-the-art nonlinear stochastic filter are conducted. Results show that MSF is more accurate and less computational intensive than the state-of-the-art filter.

碩士
國立中興大學
生醫工程研究所
102
Biocompatible three-dimensional (3D) matrices can mimic the living body environment for cell growth and further construct a biological tissue for tissue repair. 3D matrices have been drawn a lot of attentions because of their customized structures and tailor-made mechanical and chemical properties for cellular proliferation and survival after integrating with specific extracellular matrix (ECM) or biomolecules. This study is based on 3T3 fibroblasts laden 3D poly(ethylene glycol) (PEG)-hybrid biomaterial for soft tissue repair. Visible-light sensitive 3D polymer precursor solution was first prepared by mixing PEG and photosensitive PEG diacrylate (PEGDA) with ratio of 1 to 5 and further supplemented with RGD(Arg-Gly-Asp) or PRP(Platelet Rich Plasma) to form the main structure of synthesized polymer material. 3T3 fibroblasts laden RGD or PRP supplemented PEG-hybrid biomaterials were used to in vitro and in vivo evaluate their cellular proliferation and biocompatibility. Our in vitro results showed PEG-hybrid supplemented with RGD or PRP had better cellular proliferation and biocompatibility than PEG-hybrid material. After that, the cell-laden RGD or PRP supplemented 3D matrices were implanted in living mice for in-vivo evaluation of soft tissue repair. The histological examinations were used to determine the responses after 2-wk and 4-wk implantation. Our results showed RGD supplemented PEG-hybrid material had high inflammation responses after 2-wk implantation. The inflammation responses obviously decreased after 4-wk implantation. PRP supplemented PEG-hybrid material showed less the inflammation responses but higher fibrosis than RGD after 2-wk implantation. In addition, our results showed the implantation of cell-laden RGD or PRP supplemented PEG-hybrid structures has an impact on regeneration of neovessels and cell infiltration within implanted structures in 2-wk.

This thesis presents a microfluidic strategy for the in-flow definition of a 3D soft material with a tunable and perfusable microstructure. The strategy was enabled by a microfluidic device containing up to fifteen layers that were individually patterned in polydimethylsiloxane (PDMS). Each layer contained an array of ten to thirty equidistantly spaced microchannels. Two miscible fluids (aqueous solutions of alginate and CaCl2) were used as working fluids and were introduced into the device via separate inlets and distributed on chip to form a complex fluid at the exit. The fluid microstructure was tuned by altering the flow rates of the working fluids. Upon solidification of alginate in the presence of calcium chloride, the created microstructure was retained and a soft material with a tunable microstructure was formed. The produced material was subsequently perfused using the same microfluidic architecture. The demonstrated strategy potentially offers applications in materials science and regenerative medicine.

Indiana University-Purdue University Indianapolis (IUPUI)
Soft tissue manipulation is a widely used practice by manual therapists from a variety of healthcare disciplines to evaluate and treat neuromusculoskeletal impairments using mechanical stimulation either by hand massage or specially-designed tools. The practice of a specific approach of targeted pressure application using distinguished rigid mechanical tools to breakdown adhesions, scar tissues and improve range of motion for affected joints is called Instrument-Assisted Soft Tissue Manipulation (IASTM). The efficacy of IASTM has been demonstrated as a means to improve mobility of joints, reduce pain, enhance flexibility and restore function. However, unlike the techniques of ultrasound, traction, electrical stimulation, etc. the practice of IASTM doesn't involve any standard to objectively characterize massage with physical parameters. Thus, most IASTM treatments are subjective to practitioner or patient subjective feedback, which essentially addresses a need to quantify therapeutic massage or IASTM treatment with adequate treatment parameters to document, better analyze, compare and validate STM treatment as an established, state-of-the-art practice. This thesis focuses on the development and implementation of Quantifiable Soft Tissue Manipulation (QSTM™) Technology by designing an ergonomic, portable and miniaturized wired localized pressure applicator medical device (Q1), for characterizing soft tissue manipulation. Dose-load response in terms of forces in Newtons; pitch angle of the device ; stroke frequency of massage measured within stipulated time of treatment; all in real-time has been captured to characterize a QSTM session. A QSTM PC software (Q-WARE©) featuring a Treatment Record System subjective to individual patients to save and retrieve treatment diagnostics and a real-time graphical visual monitoring system has been developed from scratch on WINDOWS platform to successfully implement the technology. This quantitative analysis of STM treatment without visual monitoring has demonstrated inter-reliability and intra-reliability inconsistencies by clinicians in STM force application. While improved consistency of treatment application has been found when using visual monitoring from the QSTM feedback system. This system has also discriminated variabilities in application of high, medium and low dose-loads and stroke frequency analysis during targeted treatment sessions.

Indiana University-Purdue University Indianapolis (IUPUI)
Instrument assisted soft tissue mobilization (IASTM) is a form of massage using rigid manufactured or cast devices. The delivered force, which is a critical parameter in massage during IASTM, has not been measured or standardized for most clinical practices. In addition to the force, the angle of treatment and frequency play an important role during IASTM. As a result, there is a strong need to characterize the delivered force to a patient, angle of treatment, and stroke frequency. This thesis proposes two novel mechatronic designs for a specific instrument from Graston Technique(Model GT3), which is a frequently used tool to clinically deliver localize pressure to the soft tissue. The first design is based on compression load cells, where 4-load cells are used to measure the force components in three-dimensional space. The second design uses a 3D load cell, which can measure all three force components force simultaneously. Both designs are implemented with IMUduino microcontroller chips which can also measure tool orientation angles and provide computed stroke frequency. Both designs, which were created using Creo CAD platform, were also analyzed thorough strength and integrity using the finite element analysis package ANSYS. Once the static analysis was completed, a dynamic model was created for the first design to simulate IASTM practice using the GT-3 tool. The deformation and stress on skin were measured after applying force with the GT-3 tool. Additionally, the relationship between skin stress and the load cell measurements has been investigated. The second design of the mechatronic IASTM tool was validated for force measurements using an electronic plate scale that provided the baseline force values to compare with the applied force values measured by the tool. The load cell measurements and the scale readings were found to be in agreement within the expected degree of accuracy. The stroke frequency was computed using the force data and determining the peaks during force application. The orientation angles were obtained from the built-in sensors in the microchip.

博士
臺灣大學
醫學工程學研究所
98
Accurate measurement of the three-dimensional (3D) rigid body and surface kinematics of the natural and implanted knee is essential for many clinical applications. Skin marker-based stereophotogrammetry has been widely used in the in vivo, non-invasive measurement of 3D joint kinematics. However, the measured poses of body segments are subject to errors called soft tissue artifacts (STA). Existing techniques are limited either in their accuracy or lack of more realistic experimental evaluation of the measurement errors. The purposes of the study were to develop a volumetric model-based 2D-to-3D registration method, called the weighted edge-matching score (WEMS) method, for measuring accurate natural and implanted knee kinematics with single-plane fluoroscopy; to assess the 3D movement of skin markers relative to the underlying bones in normal subjects during functional activities; to access the effects of STA on the calculated joint variables at the knee in normal subjects during stair-ascent (SA); to quantify the STA and their effects on the calculated variables of the knee in patients with total knee replacements (TKR) during sit-to-stand (STS); and to validate the performance and effectiveness of global optimization method (GOM) with an appropriate kinematic model for compensating the STA for in vivo knee kinematics of normal, anterior cruciate ligament deficient (ACLD) and TKR subjects during functional activities. The precision of the WEMS method has been determined experimentally with cadaver knee and TKR. With the help of integrated 3D fluoroscopy method and stereophotogrammetry, considerable STA of normal and TKR subjects, during SA and STS respectively, were found and which led to significant differences of measured biomechanical variables of the knee. Compensating the effects of STA with GOM showed that the mean values of root mean squared error (RMSE) over all functional activities of all kinds of subjects were in the order of 3-6 mm for measurement of knee joint translations and about 3˚ for knee joint rotations. These findings suggested that GOM would be helpful for compensating STA in human motion analysis for basic research and clinical applications.

博士
國立臺灣大學
醫學工程學研究所
106
Soft tissue artefacts (STA) have been recognized as a major source of error as applying stereophotogrammetry for human movement analysis. It not only affects the measurement of cycling motion but also limits interpretation of the results from the stereophotogrammetry-based measurement system. Currently, study of STA absent detailed, substantial results which provide guidelines for properly interpret results of cycling. 2D-3D subject-specific model-based registration method combined with biplane fluoroscopy is considered as a non-invasive accurate measurement method. However, the technique design for alternating exposures used in clinical system is not been proposed yet. Therefore, the study aims to develop 2D-3D registration methods for alternating biplane fluoroscopy and used to quantify soft tissue artefacts in the lower limb and their effects on mechanical analysis of the knee during pedalling. A tri-alternating images registration method is proposed combined with three kinematic models (constant speed, rigid and quasi-rigid) which help to predict bone pose of the adjacent frame under sole biplane fluoroscopy or combined with assistant measurement system conditions. The methods were verified by a cadaver study. Compare to single plane and pseudo biplane registration results, fast correction algorithm based on constant speed model already decreased 89% of out-of-plane errors and the target registration error eventually less than 0.7 mm. Performance of three models were comparable to the synchronized biplane registration. The rigid kinematic model was adopted for subsequence in vivo STA quantification during pedalling. Compare to the shank markers, the thigh markers showed greater STA and were affected more by pedal resistance. The STA varied with angles of the adjacent joints, largely linearly for shank markers while non-linearly for thigh markers. Markers near a joint experienced greater ranges of STA than mid-segment markers, but tended to have smaller variation. To estimate bone pose, STA produce greater rigid translations and rotations than the nonrigid component. Range of norigid component may not able to represent accuracy of the marker cluster used to estimate bone pose. On mechanical analysis, calculated joint angles were not affected by different resistant condition. Hybrid two marker clusters to estimate bone orientation and position separately help to reduce error of calculated joint angles and moments. The method developed in the study help to apply clinical sytem for measuring accurate bone kinematics. Results of STA during pedalling help other cycling study and the experiment data will be useful for the further studies.

The extracellular matrix (ECM) plays a significant role in defining the mechanical properties of biological tissues. The proteins, proteoglycans, and glycosaminoglycans that constitute the ECM are arranged into highly organized structures (e.g. fibrils and networks). Cellular behavior is affected by the stiffness of the microenvironment and influenced by the composition and organization of the ECM. Mechanosensing of ECM stiffness by cells occurs at the fibrillar (mesoscale) level between the single molecule (microscale) and the bulk tissue (macroscale) levels. However, the mechanical behavior of ECM proteins at the mesoscale are not well defined. Thus, better understanding of the ECM building blocks responsible for functional tissue assembly is critical in order to recapitulate in vivo conditions. There is a need for the mechanical characterization of the ECM networks formed by proteins synthesized in vivo while in their native configuration.

To address this gap, my goals highlighted in this dissertation were to develop appropriate experimental and computational methodologies and investigate the 3D organization and mechanical behavior of ECM networks in situ. The ECM of developing mouse tissues was used as a model system, taking advantage of the low-density networks present at this stage. First, we established a novel decellularization technique that enhanced the visualization of ECM networks in soft embryonic tissues. Based on this technique, we then quantified tissue-dependent strain of immunostained ECM networks in situ. Next, we developed mesoscale and macroscale testing systems to evaluate ECM networks under tension. Our systems were used to investigate tendon mechanics as a function of development, calculating tangent moduli from stress - strain plots. Similarly, we characterized ECM network deformation while uniaxially loading embryonic tissues, since this testing modality is ideal for fibril and network mechanics. Taken together, this information can facilitate the fabrication of physiologically relevant scaffolds for regenerative medicine by establishing mechanical guidelines for microenvironments facilitate functional tissue assembly.