Methods for medical applications

3D face was recently investigated for various applications, including biometrics and diagnosis. Describing facial surface, i.e. how it bends and which kinds of patches is composed by, is the aim of studies in Face Analysis, whose ultimate goal is to identify which features could be extracted from three-dimensional faces depending on the application. In this study, we propose 54 novel geometrical descriptors for Face Analysis. They are generated by composing primary geometrical descriptors such as mean, Gaussian, principal curvatures, shape index, curvedness, and the coefficients of the fundamental forms. The new descriptors were mapped on 217 facial depth maps and analysed in terms of descriptiveness of facial shape and exploitability for localizing landmark points. Automatic landmark extraction stands as the final aim of this analysis. Results showed that the newly generated descriptors are suitable to 3D face description and to support landmark localization procedures.

Keywords: 3D Face , Face Analysis , Face Recognition , Geometry , Landmarks

OBJECTIVES. The purpose of this preliminary in vitro investigation was to evaluate the accuracy of an intraoral scanner in fully edentulous arches rehabilitated with 6 implants; in this clinical condition it is particularly difficult to ensure sufficient accuracy standards. MATERIALS AND METHODS. For this study a reference metal master model was provided: it had 6 implant analogs inserted to simulate a fully rehabilitated edentulous arch with implants. A scanbody made of PEEK (Polyether Ether Ketone) was inserted in each analog and the positions of each scanbody were calibrated by means of a Coordinate Measuring Machine (CMM). The master model, fitted with the scanbodies and a silicone gingiva, was acquired with the True Definition Scanner (TDS). Several series of scans were taken, each of them consisting of 10 close acquisitions, in order to arrange the calibration of the master model and the series of scans with TDS in the same day. From the mesh of each scan, a segmentation was performed to identify known points referable to both plane and cylinder shapes of the scanbodies. This operation was automatically performed by implementing a dedicated algorithm developed in the Rhinoceros 5.0 software. RESULTS. The results herein are related to one set of 10 acquisitions of the master model. Dimensional analysis assessed the effective diameter of the scanbodies measured by TDS and was compared with the reference diameter measured using a CMM, thus obtaining the dimensional error in the body diameter of the scanbody. The values of dimensional errors varied from a minimum of 15 μm to a maximum of about 39 μm, with standard deviations of up to 9 μm. The location analysis allowed to determine the average location error of the scanbodies centers with respect to the reference positions: they were in a range from 14 to 21 μm, with standard deviations of less than 10 μm. CONCLUSIONS. Within the limitations of this in vitro study, the intraoral scanner under investigation proved to be able to scan a 6 implants full arch with a level of accuracy in line with other data reported in scientific literature, or even with smaller error rates. This level of accuracy is capable of fulfilling the accuracy requirements considered clinically acceptable.

Keywords: Full arch digital impressions , Implants , Intraoral scanner , Scanning dimension errors , Scanning position errors

An essential part of cell cultivation via cell culture technology is the determination and monitoring of culture parameters. Such parameters refer to the vitality or mutual mutations of the cell culture, while the actual number of living cells in each batch indicates the correct growth rate rather than stagnation or an overgrowth of the cell culture. Today such parameters are determined by applying light microscopy methods or by staining specific constituents of the cells. Commonly such methods are a stressful procedure for the studied cells. Most applied dyes are toxic over a certain period of time and thus they are used in low concentrations only when necessary. Within this work a new kind of measurement device prototype was designed to address these problems. This device is based on the Electronic Speckle Pattern Interferometry (ESPI). ESPI is an optical high-resolution method combined with a photonic analysis system capable of analyzing cellular deformations and oscillations. In this approach the combination of a greatly modified microscope together with ESPI method is presented. The apparatus allows the determination of cellular deformation (i) at very high magnifications, (ii) with high lateral resolution. Furthermore the system studies (iii) contact free, (iv) in vitro cells, in a non-invasive and non-destructive way. A co-developed cultivation system allows monitoring the culture parameters in real time minimizing the stress for the cell culture. Since no additional substances are needed, the presented prototype is automated to a large extent and can be operated by a special control- and regulation system (CRS) based on a microcontroller development board (Arduino Mega).

Keywords: Culture parameters , ESPI , Life Science , Non-destructive , Non-invasive , Stand-alone-System

The determination of mechanical properties can provide insight into complex biochemical processes such as the cell cycle and even the progression of diseases. However, this field of biomechanical research strongly depends on a high-resolution measurement technology and a gentle stimulation method in order to examine these mostly biological samples in their original condition. In terms of this work, a different approach utilizing a modified ESPI setup and two types of ferrofluids is presented. By exposing the prepared specimen to an electro-magnetic field it has been possible to induce a local displacement and to monitor the deformation with the adapted ESPI setup.

Keywords: Detection of displacement , ESPI , Ferro fluids , HeLa , Nanoparticles

Understanding the mechanisms of traumatic ocular injury is helpful to make accurate diagnoses before the symptoms emerge and to develop specific eye protection. The comprehension of the dynamics of primary blast injury mechanisms is a challenging issue. The question is whether the pressure wave propagation and reflection alone could cause ocular damage. To date, there are dissenting opinions and no conclusive evidence thereupon. A previous numerical investigation of blast trauma highlighted the dynamic effect of pressure propagation and its amplification by the geometry of the bony orbit, inducing a resonance cavity effect and a standing wave hazardous for eye tissues. The objective of the current work is to find experimental evidence of the numerically identified phenomenon. Therefore, tests aimed at evaluating the response of porcine eyes to blast overpressure generated by firecrackers explosion were performed. The orbital cavity effect was considered mounting the enucleated eyes inside a dummy orbit. The experimental measurements obtained during the explosion tests presented in this paper corroborate the numerical evidence of a high-frequency pressure amplification, enhancing the loading on the ocular tissues, attributable to the orbital bony walls surrounding the eye.

Keywords: Amplification , Experimental study , Orbital cavity , Pressure standing wave , Primary blast injury

Introduction of collision models aided surgeons to plan their resection of the femoral and acetabular impinging deformities. Their application on the hip joint is particularly interesting in association with hip arthroscopy because with technique the vision is limited and identifying friction's zones is not easy. Although their large diffusion in the market, they still presents several limits. First, the 3D reconstruction has been used only in the preoperatory phase. Its use inside the operatory room is still not available. Furthermore the actual software lack of a pure automatized program to create the 3D model of the hip. Second, nowadays collision model's software separate and study only the bony part of the hip, erasing from the 3D reconstruction soft tissues. Third, the programs currently developed use statistical data as reference to 3d virtual models and the motion between the hip's bones. They base the motion analysis on the comparison between data extrapolated from the healthy population and data from the patient exam, consequently image processing may be inaccurate. Although according to our opinion collision model are useful even with their actual limits, in this chapter we describe the limits of the actual software and their potential development.

Objectives: This retrospective study aims to analyze the pattern of oro-facial trauma from bicycle acci- dents in Italian children and adolescents, focusing on the safety devices used. Methods: The medical records of 1405 patients of the Dental Clinic of the University of Brescia, between the age of 0 to 18, who experienced a dento-facial trauma from the use of a bicycle, were analyzed. Data regarding age, gender, weight, height, dominant hand, type of bicycle, use of safety devices, location and type of dental trauma, teeth involved, bone fractures and soft tissue lesions were recorded. Statistical analysis was performed. Results: The majority of the traumatic events occurred in children within the 8-10 years of age-range; 1085 teeth were injured, of which 975 permanent teeth (89.9%) and 110 primary teeth (10.1%). The most common dental lesions were the coronal fractures (complicated and not complicated) while the most frequently involved teeth were the upper central incisors; 11% of patients were also treated for maxillo-facial fractures. A protective helmet was worn only in 3% of the cases; not one patient wore a mouth-guard. The use of helmets was more frequent in children and adolescents riding racing-bikes competitively, compared to those who were mountain bikers (p< 0.05). Conclusions: Bicycle accidents can have serious oro-facial consequences. Therefore, national and regional efforts should be made in Italy to promote head and mouth protection in cycling.

Keywords: Child , Injuries , Prevention

The elbow ligamentous and bony structures play essential roles in the joint stability. Nevertheless, the contribution of different structures to joint stability is not yet clear and a comprehensive experimental investigation into the ligament and osseous constraints changes in relation to joint motions would be uphill and somehow unattainable, due to the impossibility of obtaining all the possible configurations on the same specimen. Therefore, a predictive tool of the joint behavior after the loss of retentive structures would be helpful in designing reconstructive surgeries and in pre-operative planning. In this work, a multibody model consisting of bones and non-linear ligamentous structures is presented and validated through comparison with experimental data. An accurate geometrical model was equipped with non-linear ligaments bundles between optimized origin and insertion points. The joint function was simulated according to maneuvers accomplished in published experimental studies which explored the posteromedial rotatory instability (PMRI) in coronoid and posterior medial collateral ligament (PB) deficient elbows. Moreover, a complete design of experiments (DOE) was explored, investigating the influence of the elbow flexion degree, of the coronoid process and of the medial collateral ligaments (MCL) structures (anterior and posterior bundles) in the elbow joint opening. The implemented computational model accurately predicted the joint behavior with intact and deficient stabilizing structures at each flexion degree, and highlighted the statistically significant influence of the MCL structures (P<0.05) on the elbow stability. The predictive ability of this multibody elbow joint model let foresee that future investigations under different loading scenarios and injured or surgically reconstructed states could be effectively simulated, helping the ligaments reconstruction optimization in terms of bone tunnel localizations and grafts pre-loading. Level of evidence: V.

Keywords: Coronoid process , Elbow stability , Medial collateral ligaments , Multibody model

Human Acellular Dermal Matrices (HADMs) have recently been employed in reconstructive surgeries which involve high mechanical resistance prerequisites (e.g. rotator cuff tears repair, Achilles tendon augmentation, breast reconstruction procedure, hernia repair), having proved its non-immunogenic response and promising mechanical properties. Nevertheless, a thorough mechanical characterization is needed in order to test HADMs response when subjected to stress levels comparable to those experienced in vivo, to confirm its applicability to the above mentioned surgical fields and to provide precise indications to surgeons. HADMs specimens have undergone biaxial tests through a custom made biaxial fixture interfaced with a uniaxial universal testing machine. Stress-strain curves were evaluated from biaxial loads measured by two load cells, and the optical measure of the displacement of four markers located in central area of specimens. Comparisons among the native human reticular dermis and HADMs demonstrated the loss of mechanical strength caused by the decellularization process. Moreover, the specimens resulted, on average, less extensible in the medio-lateral direction (namely, along the Langer lines) than in the cranio-caudal direction, confirming the correlation of dermis mechanical response with collagen fibers orientation.

Keywords: Biaxial characterization , Biaxial fixture , HADM , Human dermis , Soft tissues material model identification

Background: Double pelvic osteotomy (DPO) planning is usually performed by hip palpation, and on radiographic images which give a poor representation of the complex three-dimensional manoeuvre required during surgery. Furthermore, bone strains which play a crucial role cannot be foreseen. Objective: To support surgeons and designers with biomechanical guidelines through a virtual model that would provide bone stress and strain, required moments, and three-dimensional measurements. Methods: A multibody numerical model for kinematic analyses has been coupled to a finite element model for stress/strain analysis on deformable bodies. The model was parametrized by the fixation plate angle, the iliac osteotomy angle, and the plate offset in ventro-dorsal direction. Model outputs were: acetabular ventro-version (VV) and lateralization (L), Norberg (NA) and dorsal acetabular rim (DAR) angles, the percentage of acetabular coverage (PC), the peak bone stress, and moments required to deform the pelvis. Results: Over 150 combinations of cited parameters and their respective outcome were analysed. Curves reporting NA and PC versus VV were traced for the given patient. The optimal VV range in relation to NA and PC limits was established. The 25° DPO plate results were the most similar to 20° TPO. The output L grew for positive iliac osteotomy inclinations. The 15° DPO plate was critical in relation to DAR, while very large VV could lead to bone failure. Clinical significance: Structural models can be a support to the study and optimization of DPO as they allow for foreseeing geometrical and structural outcomes of surgical choices.

Keywords: Finite elements , Hip dysplasia , Multibody analysis , Pelvic osteotomies , Preoperative planning

This paper proposes a new automatic approach to determine the accurate measure of human teeth. The aim of the proposed computer based method is to reduce inaccuracy of measurement with respect to traditional approaches. Starting from a 3D model of the teeth which is obtained from 3D scanning, the method algorithmically evaluates the most important dimensional features detectable in central incisors. For this purpose, specific rules are put forward and implemented in original software with a view to identifying repere points, from which to detect dimensional features both unambiguously and accurately. The automatic method which is proposed here is verified by means of the analysis of real teeth and is then compared with the current state-of-the-art methods for teeth measurement.

Keywords: 3D biomedical image analysis , Computer methods for tooth analysis , Dental dimensions , Measurement accuracy , Measurement protocols in biomedicine

In this paper performance evaluation and experimental characterization of a new automatic method for measuring vertebrae are analysed. Starting to a discrete valid geometric model of the vertebra, obtained from CT-scans or 3D scanning, the method measures algorithmically vertebrae. The proposed study is performed by analysing the most used dimensional features of lumbar and thoracic real vertebrae in anthropological investigations. The results are compared with the state-of-the-art methods for vertebra measurement.

This paper describes a new motion analysis protocol for race-walking. The protocol has been tested under laboratory conditions on a real athlete of the Italian national race-walking team. The experimental setup included a motion capture system and a force platform to record both kinematic and dynamic aspects of the athletic action. Thus, any infringement of the rules can be detected, based on the measure of knee flexion-extension and the loss of ground contact. The biomechanical efficiency can be determined from the joint angles and the temporal components of gait. The results of experiments show that the protocol can be a valuable tool to assist athletes and trainers in improving race-walking technique.

Keywords: Biomechanics , Dynamics , Experimental protocol , Gait Analysis , Kinematics , Motion Capturing , Race-walking

Digital Human Modelling (DHM) is becoming a simple way to study the ergonomic behaviour of devices interacting with the human body. In particular, innovative technologies per- mit to manage big amount of data coming from several IT devices in order to better understand the correlation be- tween technical aspects and human factors. In the medical field DHM can be exploited to combine in a unique applica- tion many data types coming from several inputs (e.g. 3D scan, motion capture). In this research work, the attention is focused on the design of lower limb prosthesis around the digital human model of the patient. We present an appli- cation, which allows visualizing pressure on patient's limb while evaluating his/her gait in a unique virtual knowledge- guided environment. Such application is conceived to be usable by non IT experts, and all information are directly visualized on the digital human model of the amputee. The first part of the paper describes the platform to design lower limb prosthesis with particular attention on the use of low- cost technologies. Then, the virtual gait analysis tool is described. Finally, tests and conclusion are discussed.

Keywords: Digital human modelling , Gait analysis , Lower limb prosthesis , Pressure mapping

This paper presents a methodology and tools to improve the design of lower limb prosthesis through the measurement of pressure analysis at the interface residual limb-socket. The steps of the methodology and the design tools are presented using a case study focused on a transfemoral (amputation above knee) male amputee. The experimental setup based on F-Socket Tekscan pressure system is described as well the results of some static loading tests. Pressure data are visualized with a colour pressure map over the 3D model of the residual limb acquired using an optical low cost scanner, based on MS Kinect. Previous methodology is useful to evaluate a physical prototype; in order to improve also conceptual design, the Finite Element (FE) Analysis has been carried and results reached so far have been compared with experimental tests. Pressure distributions are comparable, even if some discrepancies have been highlighted due to sensors placements and implemented FE model. Future developments have been identified in order to improve the accuracy of the numerical simulations.

In this work we present a preliminary study on a system able to design automatically sockets for lower-limb prosthesis. The socket is the most important part of the whole prosthesis and requires a custom design specific for the patient's characteristics and her/his residuum morphology. The system takes in input the weight and the lifestyle of the patient, the tonicity level and the geometry file of the residuum, and creates a new model applying the correct geometric deformations needed to create a functional socket. In fact, in order to provide the right fit and prevent pain, we need to create on the socket load and off-load zones in correspondence of the critical anatomical areas. To identify the position of such critical areas, several neural networks have been trained using a dataset generated from real residuum models.

Keywords: CAD , Lower limb prosthesis , Neural network , Prosthetic socket

The socket for lower limb prosthesis is the central element of artificial leg that needs to be optimize with the aim to increase comfort and reduce pain. Nowadays, the modeling of this part is completely manual and based on prosthetist skills. The key parameter determining if the socket is properly designed is the pressure distribution in the interface between the skin of residual limb and the internal surface of the socket. In this paper, we expose a method to measure this pressure thought resistive pressure sensors and we illustrate a case study of a transfemoral amputee patient. A visualization tool has been developed to dynamically show pressure data on the 3D model of the residual limb during topic moments of the gait by a color scale. Achieved results and future work will be discussed in the paper.

Keywords: Gait , Lower limb prosthesis , Pressure mapping

Abstract: In the field of orthodontics, the use of Removable Thermoplastic Appliances (RTAs) to treat moderate malocclusion problems is progressively replacing traditional fixed brackets. Generally, these orthodontic devices are designed on the basis of individual anatomies and customised requirements. However, many elements may affect the effectiveness of a RTA-based therapy: accuracies of anatomical reference models, clinical treatment strategies, shape features and mechanical properties of the appliances. In this paper, a numerical model for customised orthodontic treatments planning is proposed by means of the finite element method. The model integrates individual patient's teeth, periodontal ligaments, bone tissue with structural and geometrical attributes of the appliances. The anatomical tissues are reconstructed by a multi-modality imaging technique, which combines 3D data obtained by an optical scanner (visible tissues) and a computerised tomography system (internal tissues). The mechanical interactions between anatomical shapes and appliance models are simulated through finite element analyses. The numerical approach allows a dental technician to predict how the RTA attributes affect tooth movements. In this work, treatments considering rotation movements for a maxillary incisor and a maxillary canine have been analysed by using multi-tooth models. Graphical Abstract: [Figure not available: see fulltext.]

Keywords: Anatomical modelling , Numerical analysis , Orthodontic tooth movement , Removable thermoplastic appliance

Introduction Moment-to-force ratios (M:F) define the type of tooth movement. Typically, the relationship between M:F and tooth movement has been analyzed in a single plane. Here, to improve the 3-dimensional tooth movement theory, we tested the hypothesis that the mathematical relationships between M:F and tooth movement are distinct, depending on force system directions. Methods A finite element model of a maxillary first premolar, scaled to average tooth dimensions, was constructed based on a cone-beam computed tomography scan. We conducted finite element analyses of the M:F and tooth movement relationships, represented by the projected axis of rotation in each plane, for 510 different loads. Results We confirmed that a hyperbolic equation relates the distance and M:F; however, the constant of proportionality ("k") varied nonlinearly with the force direction. With a force applied parallel to the tooth's long axis, "k" was 12 times higher than with a force parallel to the mesiodistal direction and 7 times higher than with a force parallel to the buccolingual direction. Conclusions The M:F influence on tooth movement depends on load directions. It is an incomplete parameter to describe the quality of an orthodontic load system if it is not associated with force and moment directions.

Dedicated imaging methods are among the most important tools of modern computer-aided medical applications. In the last few years, cone beam computed tomography (CBCT) has gained popularity in digital dentistry for 3D imaging of jawbones and teeth. However, the anatomy of a maxillofacial region complicates the assessment of tooth geometry and anatomical location when using standard orthogonal views of the CT data set. In particular, a tooth is defined by a sub-region, which cannot be easily separated from surrounding tissues by only considering pixel grey-intensity values. For this reason, an image enhancement is usually necessary in order to properly segment tooth geometries. In this paper, an anatomy-driven methodology to reconstruct individual 3D tooth anatomies by processing CBCT data is presented. The main concept is to generate a small set of multi-planar reformation images along significant views for each target tooth, driven by the individual anatomical geometry of a specific patient. The reformation images greatly enhance the clearness of the target tooth contours. A set of meaningful 2D tooth contours is extracted and used to automatically model the overall 3D tooth shape through a B-spline representation. The effectiveness of the methodology has been verified by comparing some anatomy-driven reconstructions of anterior and premolar teeth with those obtained by using standard tooth segmentation tools.

Keywords: 3D imaging , B-spline modelling , Cone beam computed tomography , Digital dentistry , Tooth segmentation