Methods for medical applications

In dentistry, standard radiographic imaging is a minimally invasive approach for anatomic tissue visualization and diagnostic assessment. However, this method does not provide 3D geometries of complete dental shapes, including crowns and roots, which are usually obtained by Computerized Tomography (CT) techniques. This paper describes a shape modelling process based on multi-modal imaging methodologies. In particular, 2D panoramic radiographs and 3D digital plaster casts, obtained by an optical scanner, are used to guide the creation of both shapes and orientations of complete teeth through the geometrical manipulation of general dental templates. The proposed methodology is independent on the tomographic device used to collect the panoramic radiograph.

Keywords: Dental shape modelling , Discrete radon transform , Multi-modal imaging , PAN radiograph

In this work we propose the use of image features based on visual perception for discriminating epithelium and stroma in histological images. In particular, we assess the capability of the following five visual features to correctly discriminate epithelium from stroma in digitised tissue micro-arrays of colorectal cancer: coarseness, contrast, directionality, line-likeliness and roughness. The use of features directly related to human perception makes it possible to evaluate the tissue's appearance on the basis of a set of meaningful parameters; moreover, the number of features used to discriminate epithelium from stroma is very small. In the experiments we used histologically-verified, well-defined images of epithelium and stroma to train three classifiers based on Support Vector Machines (SVM), Nearest Neighbour rule (1-NN) and Naïve Bayes rule (NB). We optimised SVM's parameters on a validation set, and estimated the accuracy of the three classifiers on a independent test set. The experiments demonstrate that the proposed features can correctly discriminate epithelium from stroma with state-of-the-art accuracy.

Keywords: Colorectal cancer , Epithelium , Image analysis , Perceptual features , Stroma

This paper investigates the use of digital polygons as a replacement for circular interpolated neighbourhoods for extracting texture features through Local Binary Patterns. The use of digital polygons has two main advantages: reduces the computational cost, and avoids the high-frequency loss resulting from pixel interpolation. The solution proposed in this work employs a sub-sampling scheme over Andres' digital circles. The effectiveness of the method was evaluated in a supervised texture classification experiment over eight different datasets. The results showed that digital polygons outperformed interpolated circular neighbourhoods in most cases.

Keywords: Digital circles , Digital polygons , Local Binary Patterns , Rotation invariance , Texture classification

The finishing and polishing of composite materials affect the restoration lifespan. The market shows a variety of finishing and polishing procedures and the choice among them is conditioned by different factors such as the resulting surface roughness. In the present study, 156 samples were realized with three composite materials,-microfilled, nanofilled and silorane-, and treated with different finishing and polishing procedures. Profilometric analyses were carried out on the samples' surface, the measured roughness values were submitted to statistical analysis. A complete factorial plan was drawn up and two-way analysis of variance (ANOVA) was carried out to investigate whether the following factors affect the values of roughness: (i) material; (ii) polishing/finishing procedure. Tukey post-hoc test was also conducted to evaluate any statistically significant differences between the material/procedure combinations. The results show that the tested materials do not affect the resulting surface quality but roughness values depend on the finishing/polishing procedure adopted. The procedures that involve: (a) the finishing with medium Sof-Lex discs and (b) the finishing with two tungsten carbide multi-blade milling cutters Q series and UF series are those that allow the lowest values of roughness to be obtained.

Keywords: Composite , Finishing , Polishing , Profilometer , Surface roughness

The objective of this study was to assess frequency and extension of the defects affecting the dentin-post interface after using different combinations of irrigants and sealers. The experimental work was conducted on single-rooted teeth extracted for orthodontic reasons. The specimens were divided into different groups, according to irrigant and endodontic cement utilized, and endodontically instrumented. After fiberglass posts cementation, cross sections were obtained at apical, middle and coronal level of the root and submitted to quantitative analyses. Different types of defects were found: bubbles, bonding defects, polymerization defect, and cement residues. The percent extension of each defect and its frequency were related to the specific irrigant/sealer combination and to the root level. Detachments of the material from dentin were found only at apical and middle levels. Chlorhexidine digluconate seems to have more beneficial effects if compared to sodium hypochlorite: samples prepared with chlorhexidine digluconate showed a higher performance, with roots including null to few defects. In detail, samples treated with chlorhexidine digluconate and Pulp Canal Sealer showed the lowest frequency and the smallest dimension of defects.

Keywords: Adhesive defects , Endodontic cements , Endoposts , Irrigants , Morphometric analysis

Quantification of 3-D deformations of human organs plays an important role in the understanding phenomena that have an impact in medical diagnosis and treatment of diseases. One important example is the mechanics of heart functions. Comparing normal deformation patterns of the cardiac cycle in healthy and diseased individuals can be a diagnostic tool that provides early and accurate indications of the onset of heart diseases. The tagging technique is an experimental mechanics method that makes it possible to utilize the extensive literature existing on the analysis of deformations utilizing the digital moire´ method for accurate and fast quantification of the heart 3-D kinematics. MRI tagging is an imaging technique used in medicine to visualize the structures of tissues of the human body in detail. MRI uses of the phenomenon of nuclear magnetic resonance to image tissues by exciting the nuclei of atoms in the tissue. Because of the different chemical composition of the tissues it can provide details that cannot be visible with CT Scans. By modulating magnetization it is possible to inscribe lattice-patterns in the tissue volume. These lattices are fixed to the under laying tissues for periods of time long enough to follow a cardiac cycle. The objective of this paper is to outline image processing techniques that can be utilized to decode the displacements and strains taking into consideration that one is dealing with large 3-D deformations that form a time sequence of images. These techniques are based on fundamental principles that have been developed in the field of digital moire´.

Keywords: Deformation of cardiac tissues , Digital moiré , Large deformations , MRI , MRI tagging

The umbilical cord is a peculiar and complex structure, about 50–60 cm in length and 1–2 cm in diameter, that is essentially composed of three vessels, i.e. the umbilical vein and two umbilical arteries, arranged in coils around the vein surrounded by a great amount of support tissue, the Wharton's Jelly (WJ) that binds and encases the umbilical vessels. WJ is a mucoid connective tissue (5 % cells, 95 % extracellular matrix) described as a three-dimensional spongy network of interlacing collagen fibers and small woven bundles of glycoprotein microfibrils with an interdispersed soluble phase composed by hydrophylic hyaluronans and proteoglycans. WJ grants the protection of the umbilical vessels against compressive forces due to fetal movements and uterine contractions and is very important to guarantee venous and arterial umbilical blood flows. WJ response to mechanical loading is not well understood; another unsolved problem concerns WJ putative contribution to store and release the energy of the cardiac cycle, therefore in maintaining the anterograde flow in the cord arteries. This article presents a preliminary study on the mechanical behavior of umbilical cord. For that purpose, an optical set up based on intrinsic moire´ will be developed. Slices cut in the transverse directions of the cord will be submitted to equibiaxial tests and specimen deformations will be monitored in real time with moire´ by printing a grating on the cord slice. In this way, it will be possible to gather information on the mechanical anisotropy of the cord.

Keywords: Anisotropy , Biomaterials , Intrinsic moiré , Mechanical characterization , Umbilical cord

This paper presents a new method for the automated processing of surface electromyography (SEMG) signals, particularly suited for the detection of muscle activation timing. The method has an intermediate level of complexity between simpler (but less performing) and more complex (but in general slower) methods, and is successfully used in the development of biomedical devices for rehabilitation carried out by our group. The method proposed here is based on a statistical approach for threshold computation that is implemented without the need of maximum voluntary contraction or relaxed state, usually required to overcome the difficulty in obtaining the threshold value. The method is compared with 10 popular automated standard methods using different types of simulated signals that approximate the behavior of real SEMG signals. Both the number of activations detected and the onset time measured are analyzed. The algorithm is then applied to real SEMG signals acquired from healthy subjects. The results are finally compared with the literature values. The results show that the proposed algorithm is the best performing method when both the number of activations and the activation timing are considered. In real applications, the algorithm gives the results compatible with the well-agreed literature data.

Keywords: Activation analysis , electromyography , measurement , muscles , signal processing , timing

The study of new systems for supporting upper limb rehabilitation is of primary importance, due to the high number of people in need of rehabilitation and the limited effectiveness of most of the current systems. The research work described in this paper proposes a VR system for upper-limb rehabilitation that is immersive, is based on hand gestures to interact with virtual objects, and which can deliver odours when a goal is reached.

The interest of people working in rehabilitation towards the possibilities offered by Virtual Reality (VR) technologies is growing in years. Through VR technologies, rehabilitation can become more engaging with respect to traditional methods, since exercises can be performed in different simulated scenarios. They can be adapted on the basis of patient's requests, and can be easily modified to have growing difficulties, according to the rehabilitation progresses. Furthermore results can be collected and monitored, even remotely, if necessary. The paper describes the development and testing of a set of exercises in a multimodal VR environment for upper limb rehabilitation. The VR environment includes technologies addressing three senses: vision, hearing and touch. The patient is asked to grab and move a number of objects in an ecologically valid environment, which corresponds to a household scenario. While s/he performs the exercises, object trajectories are recorded in order to be analyzed later on. The development as well as a preliminary testing activity are reported in the paper.

Carotid artery phantoms (CaPs) can be used as test objects to explore novel ways of enhancing the ultrasound based carotid atherosclerosis diagnosis. To achieve this goal CaPs should be anatomically realistic both in terms of geometry, acoustic and physical properties, and should allow to reproduce different pathological conditions. We propose a framework for designing CaPs of healthy and diseased arteries. To verify the framework effectiveness we constructed three CaPs: healthy, with a hard/soft plaque causing a 30%/65% vessel narrowing. Then we acquired CaPs B-mode images and performed their geometric characterization and echogenicity analysis demonstrating the framework effectiveness at realizing anthropomorphic CaPs at low cost, easily reproducing different atherosclerotic conditions.

The monitoring of vital parameters for athletes of all disciplines is becoming more and more essential, to improve performances and to ensure a constant control of athletes' physical conditions, thus preventing health risks and injuries. However, especially in amatorial competitions, the low available budget limits leads to the use of inexpensive and thus ineffective instrumentation. In this paper, a low-cost system, based on a commercial smartdevice, for monitoring purposes in the context of amatorial car races is proposed. A single-lead electrocardiographic trace, body temperature, and driver acceleration profile are simultaneously acquired, locally stored and preprocessed, and periodically sent to a cloud service, allowing data sharing and remote processing. Experimental tests operated by means of a Formula SAE car in a test track have demonstrated the effectiveness of the proposed approach for the acquisition of important data to evaluate the degree of stress of a driver during the race.

Keywords: amatorial car race , smartphone-based system , Vital parameters monitoring

Abdominal Aorta Aneurysm (AAA) affects aorta, especially above the iliac bifurcation where the Wall Shear Stress (WSS) is greater. Consequence may be fatal in case of breakage; a way to treat it is Endovascular Aneurysm Repair (EVAR) where a stent graft is placed inside the aorta without open surgery requirement. Because of the standards, stent graft can be chosen between several sizes: in some cases, this device cannot fit perfectly with the anatomy of the patient and this can lead to a not optimal behavior of the prosthesis and further complications. This study present a method to design and test specific custom-fit stent graft able to better adapt to the patient artery improving the efficiency of the prosthesis and reducing the risk of the migration of the graft as well as the fabric torn. The design method is based on a 3D geometric model of the aorta, generated from CT scan data. Centrelines and geometric data for cross sections along the aorta are the inputs necessary to define the mesh of the stent. A custom algorithm is developed to size the stent in relation to the geometric data of the specific patient; when the frame of the prosthesis is defined, a CAD-based Loft Surface has used to define surfaces between the stent rings. For the bifurcation, again CAD-based Boundary Surfaces is used. The described procedure has been also applied in a Augmented Virtual Reality simulation of the EVAR and, finally, it permits a CFD simulation to evaluate the behavior of the prosthesis inserted into the aorta.

Purpose - The purpose of this paper is to describe two different approaches for manufacturing pre-formed titanium meshes to assist prosthetically guided bone regeneration of atrophic maxillary arches. Both methods are based on the use of additive manufacturing (AM) technologies and aim to limit at the minimal intervention the bone reconstructive surgery by virtual planning the surgical intervention for dental implants placement. Design/methodology/approach - Two patients with atrophic maxillary arches were scheduled for bone augmentation using pre-formed titanium mesh with particulate autogenous bone graft and alloplastic material. The complete workflow consists of four steps: three-dimensional (3D) acquisition of medical images and virtual planning, 3D modelling and design of the bone augmentation volume, manufacturing of biomodels and pre-formed meshes, clinical procedure and follow up. For what concerns the AM, fused deposition modelling (FDM) and direct metal laser sintering (DMLS) were used. Findings - For both patients, a post-operative control CT examination was scheduled to evaluate the progression of the regenerative process and verify the availability of an adequate amount of bone before the surgical intervention for dental implants placement. In both cases, the regenerated bone was sufficient to fix the implants in the planned position, improving the intervention quality and reducing the intervention time during surgery. Originality/value - A comparison between two novel methods, involving AM technologies are presented as viable and reproducible methods to assist the correct bone augmentation of atrophic patients, prior to implant placement for the final implant supported prosthetic rehabilitation.

Keywords: CAD/CAM , Computed tomography , Implant surgery , Rapid prototyping , Titanium mesh

The production of prostheses is still not completely optimized, especially for those districts where both functional and aesthetic requirements have to be combined with the urgency of intervention. The prostheses manufactured by machining using CAD/CAM techniques represent the conventional way to obtain a "custom-made" part. However, the above-mentioned solutions are penalized by the too long manufacturing time. This limit can be overcome by using an innovative metal-forming process, i.e. the Incremental Sheet Forming (ISF), which also allows to obtain complex patient-specific geometries even if characterized by a lower precision compared to the conventional process. In this paper, alternative approaches to manufacture a skull prosthesis (i.e. conventional milling and ISF) are compared from technological and economical points of view.

Keywords: Anchoring system design , Prostheses modelling , Skull manufacturing

Patients affected by serious foot pathologies often require special orthotics to stand and walk correctly. Skilled operators obtain such insoles on the basis of manual procedures and following the prescriptions of orthopaedic technicians. The process is handicraft and time consuming. The paper presents a virtual prototyping approach which is based on dedicated foot scanners, CAD-based design tool and milling machines to obtain the bespoke footwear orthotics. The major contribution is a geometric procedure to design complex insole shapes starting from the foot scan and highly customized shoe lasts which are required in case of important deformities. The approach has been tested on several patients thanks to the collaboration with a partner insole producer and some orthopaedic centers. Patients have generally reported positive feedbacks on the comfort and functionality of the insoles.

Keywords: Foot orthotics , Insole design , Orthopaedic custom-made insoles

Ambient Assisted Living (AAL) is one of the most strategic research fields of research due to the increasing aging of the world population and the developments of assistive technologies, which enable people with specific demands to live longer and better by providing specific care. It has been demonstrated that AAL technologies provide effective support to frail people and their application is increasing in home and medical contexts with positive effects on costs reduction. However, such models have been rarely applied outside the domestic context. This paper describes the application of AAL concepts to manufacturing in order to support frail people to properly handle machine tools and complex systems. It presents an industrial case study focusing on machine tool operators: under these circumstances frailty assumes a broad sense as people have to carry out highly specialized jobs and also mild deficiencies can represent a frailty (i.e. slight reduction in sight, hands that are not perfectly steady, slightly reduced mobility or human force). The case study in particular aims at designing an adaptive user interface based on AAL principles and user-centered approach to support frail operators to work better and more safely.

Intervertebral disc (IVD) degeneration is one of the main causes of low back pain. Current surgical treatments are complex and generally do not fully restore spine mobility. Development of injectable extracellular matrix-based hydrogels offers an opportunity for minimally invasive treatment of IVD degeneration. Here we analyze a specific formulation of collagen-low molecular weight hyaluronic acid (LMW HA) semi-interpenetrating network (semi-IPN) loaded with gelatin microspheres as a potential material for tissue engineering of the inner part of the IVD, the nucleus pulposus (NP). The material displayed a gel-like behavior, it was easily injectable as demonstrated by suitable tests and did not induce cytotoxicity or inflammation. Importantly, it supported the growth and chondrogenic differentiation potential of mesenchymal stem cells (MSC) and nasal chondrocytes (NC) in vitro and in vivo. These properties of the hydrogel were successfully combined with TGF-β3 delivery by gelatin microspheres, which promoted the chondrogenic phenotype. Altogether, collagen-LMW HA loaded with gelatin microspheres represents a good candidate material for NP tissue engineering as it combines important rheological, functional and biological features.

Keywords: Chondrocyte , Collagen , Hydrogel , Intervertebral disc , Mesenchymal stem cell

In the past few years, researchers have focused on the design and development of three-dimensional (3D) advanced scaffolds, which offer significant advantages in terms of cell performance. The introduction of magnetic features into scaffold technology could offer innovative opportunities to control cell populations within 3D microenvironments, with the potential to enhance their use in tissue regeneration or in cell-based analysis. In the present study, 3D fully biodegradable and magnetic nanocomposite scaffolds for bone tissue engineering, consisting of a poly(ε-caprolactone) (PCL) matrix reinforced with iron-doped hydroxyapatite (FeHA) nanoparticles, were designed and manufactured using a rapid prototyping technique. The performances of these novel 3D PCL/FeHA scaffolds were assessed through a combination of theoretical evaluation, experimental in vitro analyses and in vivo testing in a rabbit animal model. The results from mechanical compression tests were consistent with FEM simulations. The in vitro results showed that the cell growth in the magnetized scaffolds was 2.2-fold greater than that in non-magnetized ones. In vivo experiments further suggested that, after only 4 weeks, the PCL/FeHA scaffolds were completely filled with newly formed bone, proving a good level of histocompatibility. All of the results suggest that the introduction of magnetic features into biocompatible materials may confer significant advantages in terms of 3D cell assembly.

Keywords: Bone tissue engineering , Experimental/theoretical analysis , Nanocomposite , Rapid prototyping , Scaffold

In this research work, the authors developed and tested a low cost wearable and portable hand exoskeleton to assist people with physical disabilities in their everyday lives. Focusing on hand opening disabilities, the proposed actuated orthoses could support and enable daily gestures such as shacking hands or grasping objects. The Hand Exoskeleton System (HES) prototype is based on a cable-driven architecture applied to a single-phalanx mechanism. The preliminary prototype of the system has been successfully built and is currently under testing with a patient to verify its performance from a patient viewpoint.