Robust point correspondence applied to two and three-dimensional image registration

Accurate and robust correspondence calculations are very important in many medical and biological applications. Often, the correspondence calculation forms part of a rigid registration algorithm, but accurate correspondences are especially important for elastic registration algorithms and for quantifying changes over time. In this paper, a new correspondence calculation algorithm, CSM (correspondence by sensitivity to movement), is described. A robust corresponding point is calculated by determining the sensitivity of a correspondence to movement of the point being matched. If the correspondence is reliable, a perturbation in the position of this point should not result in a large movement of the correspondence. A measure of reliability is also calculated. This correspondence calculation method is independent of the registration transformation and has been incorporated into both a 2D elastic registration algorithm for warping serial sections and a 3D rigid registration algorithm for registering pre and postoperative facial range scans. These applications use different methods for calculating the registration transformation and accurate rigid and elastic alignment of images has been achieved with the CSM method. It is expected that this method will be applicable to many different applications and that good results would be achieved if it were to be inserted into other methods for calculating a registration transformation from correspondence

Rapid prototyping for biomedical engineering: current capabilities and Challenges

A new set of manufacturing technologies has emerged in the past decades to address market requirements in a customized way and to provide support for research tasks that require prototypes. These new techniques and technologies are usually referred to as rapid prototyping and manufacturing technologies, and they allow prototypes to be produced in a wide range of materials with remarkable precision in a couple of hours. Although they have been rapidly incorporated into product development methodologies, they are still under development, and their applications in bioengineering are continuously evolving. Rapid prototyping and manufacturing technologies can be of assistance in every stage of the development process of novel biodevices, to address various problems that can arise in the devices' interactions with biological systems and the fact that the design decisions must be tested carefully. This review focuses on the main fields of application for rapid prototyping in biomedical engineering and health sciences, as well as on the most remarkable challenges and research trends

Geometric Modeling of Cellular Materials for Additive Manufacturing in Biomedical Field: A Review

Advances in additive manufacturing technologies facilitate the fabrication of cellular materials that have tailored functional characteristics. The application of solid freeform fabrication techniques is especially exploited in designing scaffolds for tissue engineering. In this review, firstly, a classification of cellular materials from a geometric point of view is proposed; then, the main approaches on geometric modeling of cellular materials are discussed. Finally, an investigation on porous scaffolds fabricated by additive manufacturing technologies is pointed out. Perspectives in geometric modeling of scaffolds for tissue engineering are also proposed

Development of 3D CAD/FEM Analysis System for Natural Teeth and Jaw Bone Constructed from X-Ray CT Images

A three-dimensional finite element model of the lower first premolar, with the three layers of enamel, dentin, and pulp, and the mandible, with the two layers of cortical and cancellous bones, was directly constructed from noninvasively acquired CT images. This model was used to develop a system to analyze the stresses on the teeth and supporting bone structure during occlusion based on the finite element method and to examine the possibility of mechanical simulation

Applications of 3D printing on craniofacial bone repair: A systematic review

Objectives Three-dimensional (3D) bioprinting, a method derived from additive manufacturing technology, is a recent and ongoing trend for the construction of 3D volumetric structures. The purpose of this systematic review is to summarize evidence from existing human and animal studies assessing the application of 3D printing on bone repair and regeneration in the craniofacial region. Data & sources A rigorous search of all relevant clinical trials and case series was performed, based on specific inclusion and exclusion criteria. The search was conducted in all available electronic databases and sources, supplemented by a manual search, in December 2017. Study selection 43 articles (6 human and 37 animal studies) fulfilled the criteria. The human studies included totally 81 patients with craniofacial bone defects. Titanium or hydroxylapatite scaffolds were most commonly implanted. The follow-up period ranged between 6 and 24 months. Bone repair was reported successful in nearly every case, with minimal complications. Also, animal intervention studies used biomaterials and cells in various combination, offering insights into the techniques, through histological, biochemical, histomorphometric and microcomputed tomographic findings. The results in both humans and animals, though promising, are yet to be verified for clinical impact. Conclusions Future research should be focused on well-designed clinical trials to confirm the short- and long- term efficacy of 3D printing strategies for craniofacial bone repair. Clinical significance Emerging 3D printing technology opens a new era for tissue engineering. Humans and animals on application of 3D printing for craniofacial bone repair showed promising results which will lead clinicians to investigate more thoroughly alternative therapeutic methods for craniofacial bone defects

Integrated Methodologies and Technologies for the Design of Advanced Biomedical Devices

Biomedical devices with tailored properties were designed using advanced methodologies and technologies. In particular, design for additive manufacturing, reverse engineering, material selection, experimental and theoretical analyses were properly integrated. The focus was on the design of: i) 3D additively manufactured hybrid structures for cranioplasty; ii) technical solutions and customized prosthetic devices with tailored properties for skull base reconstruction after endoscopic endonasal surgery; iii) solid-lattice hybrid structures with optimized properties for biomedical applications. The feasibility of the proposed technical solutions was also assessed through virtual and physical models

Dental cone beam CT : An updated review

Cone beam computed tomography (CBCT) is a diverse 3D x-ray imaging technique that has gained significant popularity in dental radiology in the last two decades. CBCT overcomes the limitations of traditional twodimensional dental imaging and enables accurate depiction of multiplanar details of maxillofacial bony structures and surrounding soft tissues. In this review article, we provide an updated status on dental CBCT imaging and summarise the technical features of currently used CBCT scanner models, extending to recent developments in scanner technology, clinical aspects, and regulatory perspectives on dose optimisation, dosimetry, and diagnostic reference levels. We also consider the outlook of potential techniques along with issues that should be resolved in providing clinically more effective CBCT examinations that are optimised for the benefit of the patient.Peer reviewe

Interactive design of dental implant placements through CAD-CAM technologies: from 3D imaging to additive manufacturing

In the field of oral rehabilitation, the combined use of 3D imaging technologies and computer-guided approaches allows the development of reliable tools to be used in preoperative assessment of implant placement. In particular, the accurate transfer of the virtual planning into the operative field through surgical guides represents the main challenge of modern dental implantology. Guided implant positioning allows surgical and prosthetic approaches with minimal trauma by reducing treatment time and decreasing patient’s discomfort. This paper aims at defining a CAD/CAM framework for the accurate planning of flapless dental implant surgery. The system embraces three major applications: (1) freeform modelling, including 3D tissue reconstruction and 2D/3D anatomy visualization, (2) computer-aided surgical planning and customised template modelling, (3) additive manufacturing of guided surgery template. The tissue modelling approach is based on the integration of two maxillofacial imaging techniques: tomographic scanning and surface optical scanning. A 3D virtual maxillofacial model is created by matching radiographic data, captured by a CBCT scanner, and surface anatomical data, acquired by a structured light scanner. The pre-surgical planning process is carried out and controlled within the CAD application by referring to the integrated anatomical model. A surgical guide is then created by solid modelling and manufactured by additive techniques. Two different clinical cases have been approached by inserting 11 different implants. CAD-based planned fixture placements have been transferred into the clinical field by customised surgical guides, made of a biocompatible resin and equipped with drilling sleeves

DESIGN STRATEGIES AND ADDITIVE MANUFACTURING OF 3D CUSTOMIZED SCAFFOLDS WITH OPTIMIZED PROPERTIES FOR CRANIOFACIAL TISSUE ENGINEERING

3D customized scaffolds for craniofacial tissue engineering were designed using advanced strategies and technologies. Specifically, reverse engineering, additive manufacturing, material selection, experimental and theoretical analyses were properly integrated. The focus was on: i) design strategies of 3D customized nanocomposite scaffolds for hard tissue regeneration; ii) an engineered design of 3D additive manufactured nanocomposite scaffolds with optimized properties; iii) an approach toward the design of 3D customized scaffolds for large cranial defects

Fuzzy Hybrid Method for the Reconstruction of 3D Models Based on CT/MRI Data

This research proposes a hybrid method for improving the segmentation accuracy of reconstructed 3D models from computed tomography/magnetic resonance imaging (CT/MRI) data. A semi-automatic hybrid method based on combination of Fuzzy C-Means clustering (FCM) and region growing (RG) is proposed. In this approach, FCM is used in the first stage as a preprocessing step in order to classify and improve images by assigning pixels to the clusters for which they have the maximum membership, and manual selection of the membership intensity map with the best contrast separation. Afterwards, automatic seed selection is performed for RG, for which a new parameter standard deviation (STD) of pixel intensities, is included. It is based on the selection of an initial seed inside a region with maximum value of STD. To evaluate the performance of the proposed method, it was compared to several other segmentation methods. Experimental results show that the proposed method overall provides better results compared to other methods in terms of accuracy. The average sensitivity and accuracy rates for cone-beam computed tomography CBCT 1 and CBCT 2 datasets are 99 %, 98.4 %, 47.2 % and 89.9 %, respectively. For MRI 1 and MRI 2 datasets, the average sensitivity and accuracy values are 99.1 %, 100 %, 75.6 % and 99.6 %, respectively. The average values for the Dice coefficient and Jaccard index for the CBCT 1 and CBCT 2 datasets are 95.88, 0.88, 0.6, and 0.51, respectively, while for MRI 1 and MRI 2 datasets, average values are 0.96, 0.93, 0.81 and 0.7, respectively, which confirms the high accuracy of the proposed method