Methods for medical applications

Medical image segmentation, especially for biological soft tissues, is an issue of great interest. The aim of this study is to evaluate the segmentation performance of a commercial and an open-source software, to segment aortic root and coronary arteries. 3D printing stereolithography technology was used to generate ground truth models, which were then re-acquired by means of a micro-CT scanner. Measurements from the printed and reconstructed models with both the software were compared, in order to evaluate the level of agreement. In the second phase of this study, Computational Fluid Dynamics (CFD) simulations were conducted, to compare the outputs between the models segmented with the two software. The goal was to understand how differences in the segmentation process propagate in CFD results. Results showed that both software guarantee satisfactory segmentation performance, with average geometrical differences between reconstructed and physical models in the order of a few percentage points. However, when we consider thin details, as a sharp stenotic region, the commercial validated software seems to be more accurate in replicating the real anatomy. We also realized how apparently negligible geometrical differences, varying the employed software, can turn into enormous variations of hemodynamic parameters, such as velocity and wall shear stress, which place in the centre the delicate role the segmentation process holds. This evidence is crucial in the biomedical field and especially in a coronary arteries study, where CFD simulations can be exploited as a starting point for surgery considerations.

Keywords: Additive manufacturing , CFD , Coronary arteries , Digital twins , Segmentation

Additive manufacturing technologies are increasingly taking place in the medical field, enabling the creation of graspable patient-specific anatomical models. Because of their potentiality in improving the understanding of complex anatomies and their shown effectiveness for residents' training, devices testing and planning of innovative surgical interventions, 3D printed models have been incorporated also into cardiac surgery and interventional cardiology. To offer valid and reliable support, however, these printed models are often required to be flexible, with an adequate mechanical response, especially when they aim at replicating soft tissues. The goal of this paper is to provide a high-quality and robust template of a patient-specific whole heart model, obtained starting from a Computed Tomography dataset and exploiting a material jetting printer. Due to the significant shape complexity and the variability in compliance featuring the human heart, the selection of the materials have been diversified, taking into account different model wall thicknesses. Thanks to the capability of the material jetting technology, the 3D model of the heart has been printed with two different material assignments, designed to get highly realistic feedback and reduce the gap between the real heart and the printed ones. Eventually, an accuracy evaluation of the printed model has been performed, by means of a laser 3D scanner. Some further considerations about time and costs required to produce the model are part of the paper, together with a discussion about potential areas of improvement, from materials characterization to the need of speeding up and automating the segmentation procedure.

Keywords: Additive Manufacturing , Heart , Material Jetting , Patient-specific Anatomy , Segmentation

An Abdominal Aortic Aneurysm (AAA) is a focal dilatation of the abdominal aorta, which if not treated can rupture with catastrophic internal bleeding. Besides open surgery, minimally invasive EndoVascular Aneurysm Repair (EVAR) has gradually taken place in clinical practice. In this paper, a workflow to evaluate the hemodynamic changes in a patient-specific AAA after stent-graft implantation is proposed. After the extraction from Computed Tomography (CT) images of the AAA 3D model, a patient-specific idealized stent-graft was obtained by means of CAD software. Models were then imported into the simulation environment, where a proper mesh was generated. Once calculations were completed, parameters of interest were extracted and a comparison between values before and after stent-graft implantation was conducted. Results show that, as expected, the introduction of the stent-graft makes the flow pattern smoother and more regular, with no vortices. This is because the stent provides a more physiological geometry for the blood flow, without the aneurysm enlargement. Anyway, simulations were conducted in a simplified way, being the main aim of the paper the implementation of the workflow by which parameters of interest can be obtained. As a development, the introduction of more refined boundary conditions, maybe considering data of the real patient, would increase the reliability of the simulations. A further step would be the passage from Computational Fluid Dynamics (CFD) to Fluid-Structure Interaction (FSI) simulations, so considering wall vessel compliance.

Keywords: AAA , CFD , Stent-graft

Worldwide, stroke is the third cause of disability. The majority of people affected by this disease cannot perform activities of daily living. Bringing the therapy to the patients' home is complex, and in literature, there are still open challenges to face. Starting from therapists' and patients' needs, this paper describes a possible solution: HANDY, a rehabilitative active hand exoskeleton for post-stroke patients. With a desktop application, they perform three different types of exercises: passive, active and based on activities of daily living. They can also control the exoskeleton themselves in a serious-game approach with a leap motion controller. We evaluated our method with patients at the Villa Beretta rehabilitative center. Preliminary results from the session about comfort, usability and willingness to utilize the system are promising.

Keywords: Additive manufacturing , CAD modeling , Hand exoskeleton , Interactive applications , Stroke

Currently, the growing need for highly customized implants has become one of the key aspects to increase the life expectancy and reduce time and costs for prolonged hospitalizations due to premature failures of implanted prostheses. According to the literature, several technological solutions are considered suitable to achieve the necessary geometrical complexity, from the conventional subtractive approaches to the more innovative additive solutions. In the case of cranial prostheses, which must guarantee a very good fitting of the region surrounding the implant in order to minimize micromotions and reduce infections, the need of a product characterized by high geometrical complexity combined with both strength and limited weight, has pushed the research towards the adoption of manufacturing processes able to improve the product's quality but being fast and flexible enough. The attention has been thus focused in this paper on sheet metal forming processes and, namely on the Single Point Incremental Forming (SPIF) and the Superplastic Forming (SPF). In particular, the complete procedure to design and produce titanium cranial prostheses for in vivo tests is described: starting from Digital Imaging and COmmunications in Medicine (DICOM) images of the ovine animal, the design was conducted and the production process simulated to evaluate the process parameters and the production set up. The forming characteristics of the prostheses were finally evaluated in terms of thickness distributions and part's geometry. The effectiveness of the proposed methodology has been finally assessed through the implantation of the manufactured prostheses in sheep.

Keywords: Custom prosthesis , In vivo tests , Single point incremental forming , Superplastic forming , Ti‐6Al‐4V ELI

Generative Design (GD) is an emerging approach to the development of industrial products. Its key-point is the automatism in defining the shapes of artifacts by obeying to parameters describing the environment the artifacts will interact with, their mechanical properties, their materials and the manufacturing processes that will be used to build them. This paper describes some GD experiences in medicine, aimed at developing artifacts for maxillo-facial surgery. Once highlighted a real surgical case, designers, engineers and surgeons worked together to set the parameters to enable GD generating the artifact to replace a part of a patient's jaw hit by a genetic disease. Three adoptions of the GD algorithms occurred, along with parameter refinement and integration time after time. Designers, engineers and surgeons reasoned together on the solutions; this led to considerations about the suitability of GD in maxillo-facial surgery and about the current limits of this approach, as well as to some hints for carrying on the research activities in the near future.

Keywords: CAD in medicine , Generative design , Maxillo-facial surgery

Burn injuries requires post-accident medical treatment. However, the treatment of burns does not end with first aid because scarred skin must be managed for many years, and in some circumstances, for life. The methods used to evaluate the state of a burn scar based, for instance, on Patient and Observer Scar Assessment Scale or similar ones, often lacks in univocally assessing the scarred skin's state of health. As a result, the primary aim of this research is to design and build a prototype that can support the doctor during scar assessment, and eventually therapy, by providing objective information on the state of the lesion, particularly the value of skin pliability. The developed tool is based on the depressomassage treatment probe named LPG, currently used to treat burn scars in a number of hospitals. It consists of a non-invasive massage technique using a mechanical device to suction and mobilize scar tissue and is used as a post-operative treatment to speed up the healing process to make the mark of the scar less visible. The prototype is specifically designed to be manufactured using Additive Manufacturing and was validated comparing its performances against the ones of a certified instrument (i.e., the Romer Absolute ARM with RS1 probe). Validation was carried out by designing and developing a tool to put the RS1 probe in the same measurement conditions of the new prototype probe. Tests performed to assess the performance of the devised prototype show that the probe developed in this work is able to provide measurements with a sufficient degree of accuracy (maximum error ±0.1 mm) to be adopted for a reliable estimation of the pliability value in a hospital environment.

Keywords: 3D measurement , additive manufacturing (3D printing) , burn scars , pliability , reverse engineering

Ear reconstruction surgery is a very demanding intervention for plastic surgeons. The results rely heavily on the “artistic skills” of the surgeon who has the task of creating a three-dimensional sculpture using harvested costal cartilage capable of replicating the shape of a physiological ear. By exploiting a combination of Reverse Engineering, CAD modelling, and Additive Manufacturing tools, it is possible to create efficient and highly personalized simulators to train and support the surgeon before and during surgery. In fact, the flexibility of these techniques allows the development of custom-made medical devices, designed directly on the patient's anatomy. In order to make the simulation as realistic as possible, this work focuses specifically on the creation of accurate costal cartilage replicas, both in terms of geometry and mechanical properties of the material, addressing two aspects: the systematization and automation of the CAD mould modelling procedure and the study of the most efficient mould casting materials.

Keywords: Costal cartilage mould , Ear reconstruction , Medical simulation

Tissue engineering or tissue reconstruction/repair/regeneration may be considered as a guiding strategy in oral and maxillofacial surgery, as well as in endodontics, orthodontics, peri-odontics, and daily clinical practice. A wide range of techniques has been developed over the past years, from tissue grafts to the more recent and innovative regenerative procedures. Continuous research in the field of natural and artificial materials and biomaterials, as well as in advanced scaffold design strategies has been carried out. The focus has also been on various growth factors involved in dental tissue repair or reconstruction. Benefiting from the recent literature, this review paper illustrates current innovative strategies and technological approaches in oral and maxillofacial tissue engineering, trying to offer some information regarding the available scientific data and practical applications. After introducing tissue engineering aspects, an overview on additive manufacturing technologies will be provided, with a focus on the applications of superparamagnetic iron oxide nanoparticles in the biomedical field. The potential applications of magnetic fields and magnetic devices on the acceleration of orthodontic tooth movement will be analysed.

Keywords: 3D/4D printing , Dentistry , Design for additive manufacturing , Magnetism , SPIONs , Tissue engineering

The aim of this study was to evaluate the effect of a time‐dependent magnetic field on the biological performance of periodontal ligament stem cells (PDLSCs). A Western blot analysis and Alamar Blue assay were performed to investigate the proliferative capacity of magnetically stimulated PDLSCs (PDLSCs MAG) through the study of the MAPK cascade (p‐ERK1/2). The observation of ALP levels allowed the evaluation of the effect of the magnetic field on osteogenic differentiation. Metabolomics data, such as oxygen consumption rate (OCR), extracellular acidification rate (ECAR) and ATP production provided an overview of the PDLSCs MAG metabolic state. Moreover, the mitochondrial state was investigated through confocal laser scanning microscopy. Results showed a good viability for PDLSCs MAG. Magnetic stimulation can activate the ERK phosphorylation more than the FGF factor alone by promoting a better cell proliferation. Osteogenic differentiation was more effectively induced by magnetic stimulation. The metabolic panel indicated significant changes in the mitochondrial cellular respiration of PDLSCs MAG. The results suggested that periodontal ligament stem cells (PDLSCs) can respond to biophysical stimuli such as a time‐dependent magnetic field, which is able to induce changes in cell proliferation and differentiation. Moreover, the magnetic stimulation also produced an effect on the cell metabolic profile. Therefore, the current study demonstrated that a time‐dependent magnetic stimulation may improve the regenerative properties of PDLSCs.

Keywords: Cellular respiration , Magnetic stimulation design , Metabolomics , Osteogenesis , Stem cells , Tissue engineering

A computer-aided design/computer-aided manufacturing (CAD/CAM) resin block material for restoration of single-implant abutments can be milled and cemented on an optimized standard titanium abutment as a cheaper solution or, alternatively, individualization of the crown–abutment connection is required to fulfill the same mechanical requirements. The aim of this study was to evaluate how different structural and geometric configurations of the abutment influence the resistance of a nano ceramic resin crown (NCRC). During the test, 30 implants with an internal conical tapered configuration were considered. Each implant received a standard titanium abutment: in group 1, NCRCs were directly bonded to the titanium abutments; in group 2, NCRCs were cemented on a customized zirconia framework and then cemented on a standardized titanium abutment. Three crowns of each group were submitted to a static load test until failure. The remaining crowns were submitted to a fatigue test protocol with a dynamic load. The static and dynamic test showed earlier failure for group 1. In group 1, complete breaking of NCRCs was observed for all samples, with an almost total titanium abutment exposition. In the static tests, group 2 showed a mode of failure that involved only the crown, which partially debonded from the zirconia abutment. Within the limitations of the present preliminary study, it was possible to conclude that the shape of the abutment mainly influences the fatigue strength compared to the static tensile strength. The results of the performed test show that NCRC bonded to the customized zirconia abutments, and presented a 75% survival rate when compared to the same material bonded directly to a standard titanium abutment.

Keywords: CAD-CAM , Fatigue test , NCRC , Patient specific design

Purpose: To compare the flexural properties and the adhesion of Lactobacillus salivarius (LS), Streptococcus mutans (SM), and Candida albicans (CA) on heat-polymerized (CV), CAD-CAM milled (CAD), or 3D-printed (3D) Poly (methylmethacry-late) (PMMA). Methods: Ultimate Flexural Strength (UFS), Flexural Strain (FS) (%) at Flexural Strength, and Flexural Modulus (FM) of specimens (65.0×10.0×3.3 mm) from each PMMA group (n=6) were calculated by using the 3-point bending test. The surface roughness profiles (R) were measured before and after polishing with a contact profilometer. LS, SM, and CA adhesion on PMMA specimens (n=18) (10 mm in diameter, 3 mm in height) was assessed after 90 minutes and 16 hours by using scanning electron microscopy. The Kruskal-Wallis test with post hoc analysis was performed to compare the groups (alpha=0.05). Results: Mean UFS values were 80.79±7.64 MPa for CV, 110.23±5.03 MPa for CAD, and 87.34±6.39 MPa for 3D. Mean FS values were 4.37±1.04% for CV, 4.71±0.62% for CAD, and 6.19±0.13 % for 3D. Mean FM values were 2542±301 MPa for CV, 3435±346 MPa for CAD, and 2371±197 MPa for 3D. CAD had the lowest average R value (0.29±0.16 µm) before polishing, and bacterial adhesion after 90 minutes of incubation. R value and microbial adhesion were not different amongst groups after polishing and 16 hours of incubation, respectively. Conclusion: The CAD group displayed the best flexural properties, except for FS, the lowest roughness before polishing and bacterial adhesion after 90 minutes of incubation. All tested PMMAs had similar surface roughness after polishing, and microbial adhesion after 16 hours of incubation.

Keywords: 3D-printer , CAD/CAM , Complete denture , Overdenture , PMMA

Introduction: The current study presents a deep learning framework to determine, in real-time, position and rotation of a target organ from an endoscopic video. These inferred data are used to overlay the 3D model of patient's organ over its real counterpart. The resulting augmented video flow is streamed back to the surgeon as a support during laparoscopic robot-assisted procedures. Methods: This framework exploits semantic segmentation and, thereafter, two techniques, based on Convolutional Neural Networks and motion analysis, were used to infer the rotation. Results: The segmentation shows optimal accuracies, with a mean IoU score greater than 80% in all tests. Different performance levels are obtained for rotation, depending on the surgical procedure. Discussion: Even if the presented methodology has various degrees of precision depending on the testing scenario, this work sets the first step for the adoption of deep learning and augmented reality to generalise the automatic registration process.

Keywords: abdominal , Kidney , prostate

Objective: To validate the use of a polyblend tape suture in equine laryngoplasty (PL). Study design: Experimental study. Animals: Thirty-two cadaveric larynges. Methods: Each larynx was randomly assigned to 1 of 4 groups: PL with polyblend tape suture (TigerTape), without (TT) or with a cannula (TTC) in the muscular process of the arytenoid cartilage, and PL with polyester suture (Ethibond), without (EB) or with a cannula (EBC). Construct stiffness, total migration, creep, and drift values were measured after 3000 cycles. The specimens were then loaded to failure to assess their residual properties: load at failure, total energy, displacement, and 2 stiffness coefficients. Results: After cyclic testing, the total migration and creep were lower in TTC (6.36 ± 1.20 mm; 1.35 ± 0.38 mm/s) than in EB (11.12 ± 4.20 mm; 3.39 ± 2.68 mm/s) and in the TT constructs (11.26 ± 1.49 mm; 3.20 ± 0.54 mm/s); however, no difference was found with EBC (9.19 ± 3.18 mm; 2.14 ± 0.99). A correlation was found between total migration and creep (R =.85). The TTC constructs failed at higher loads (129.51 ± 33.84 N) than EB (93.16 ± 18.21 N) and EBC (81.72 ± 13.26 N) whereas the EB and EBC constructs were less stiff than TT and TTC (P <.001). Conclusion: Biomechanical properties were generally superior for the TTC constructs tested under cyclical loading. The TT and TTC constructs failed at a higher load than EB and EBC constructs. The cannula in TTC and EBC reduced the failure at the muscular process. Clinical significance: These results provide evidence to support the in vivo evaluation of the polyblend tape suture with or without a cannula in the muscular process for laryngoplasty in horses.

One of the main limitations in subject-centred design approach is represented by getting 3D models of the region of interest. Indeed, 3D reconstruction from imaging data (i.e., computed tomography scans) is expensive and exposes the subject to high radiation doses. Statistical Shape Models (SSMs) are mathematical models able to describe the variability associated to a population and allow predicting new shapes tuning model parameters. These parameters almost never have a physical meaning and so they cannot be directly related to morphometric features. In this study a gender-combined SSM model of the human mandible was setup, using Generalised Procrustes Analysis and Principal Component Analysis on a dataset of fifty mandibles. Twelve morphometric features, able to characterise the mandibular bone and readily collectable during external examinations, were recorded and correlated to SSM parameters by a multiple linear regression approach. Then a cross-validation procedure was performed on a control set to determine the combination of features able to minimise the average deviation between real and predicted shapes. Compactness of the SSM and main modes of deformations have been investigated and results consistent with previous works involving a higher number of shapes were found. A combination of five features was proved to characterise predicted shapes minimising the average error. As completion of the work, a male SSM was developed and performances compared with those of the combined SSM. The features-based model here proposed could represent a useful and easy-to-use tool for the generation of 3D customised models within a virtual interactive design environment.

Keywords: Features selection , Mandible , Morphometric measurements , PCA , Predicted shapes , Statistical shape model , Subject-specific model

Purpose: The scope of the work is to present the state of the art of robotically assisted surgical systems and to give a general idea about how technology can help today and tomorrow robotic surgery. The road to innovation passes through research and on field trials; for this reason, not only commercial surgery robots, but also innovative prototype robots, proposed by the Academic world, are presented. Design/methodology/approach: Following a short introduction, robotically assisted surgery systems are introduced discussing their architectures and main peculiarities. A further section is dedicated to the key enabling technologies that will make possible to improve current systems and that will lead to a new generation of surgical robotic systems able to meet the patient's needs and facilitate the surgeon's task. Finally, brief concluding comments are given. Findings: The idea of using robots for surgery was born many years ago and in a short time a market demand was created. Today the market is very dynamic, and several new products are updated and created for the execution of both traditional and new procedures. The article provides a guide for the reader who has an interest in this area. Originality/value: This paper provides an insight into the commercial robotic surgical systems and a look on research prototypes from academic and industrial worlds.

Keywords: haptic feedback , laparoscopy , miniature instruments , minimally invasive surgery , remote surgery , robot surgery

Background: Despite its relatively low lifetime prevalence, the health, social, and economic burden of Schizophrenia is very significant. In the last 10 years, several studies have analysed the economic burden of Schizophrenia, even if there is a lack of research that has considered the actual cost for the community as the result of each event in the patient's history. Objective: The present study aims to cover this gap by proposing a novel model to evaluate better the cost of Schizophrenia with real data from medical records. Methods: We applied (i) a ‘real life' analysis of medical database to capture each event of the clinical history and healthcare that could have an economic impact; and (ii) a novel Activity-Based Costing model to quantify the overall annual economic burden of a patient with Schizophrenia treated by public mental health services. We carried out the study with 523 patients with a diagnosis of Schizophrenia in the Department of Mental Health of Bari, in the South of Italy. Results: Our results reveal an overall cost of €41.290 per patient with Schizophrenia per year. Almost half of the cost is due to rehabilitation. The second most important factor is instead related to disability and loss of productivity. Conclusions: We believe that the present approach represents the most effective method to properly estimate actual costs when real-life data are available compared with other studies mainly based on prevalence-based approaches.

Keywords: activity-based costing , cost of Schizophrenia , public mental health services

Augmented reality robot-assisted partial nephrectomy (AR-RAPN) is limited by the need of a constant manual overlapping of the hyper-accuracy 3D (HA3D) virtual models to the real anatomy. To present our preliminary experience with automatic 3D virtual model overlapping during AR-RAPN. To reach a fully automated HA3D model overlapping, we pursued computer vision strategies, based on the identification of landmarks to link the virtual model. Due to the limited field of view of RAPN, we used the whole kidney as a marker. Moreover, to overcome the limit of similarity of colors between the kidney and its neighboring structures, we super-enhanced the organ, using the NIRF Firefly fluorescence imaging technology. A specifically developed software named “IGNITE” (Indocyanine GreeN automatIc augmenTed rEality) allowed the automatic anchorage of the HA3D model to the real organ, leveraging the enhanced view offered by NIRF technology. Ten automatic AR-RAPN were performed. For all the patients a HA3D model was produced and visualized as AR image inside the robotic console. During all the surgical procedures, the automatic ICG-guided AR technology successfully anchored the virtual model to the real organ without hand-assistance (mean anchorage time: 7 seconds), even when moving the camera throughout the operative field, while zooming and translating the organ. In 7 patients with totally endophytic or posterior lesions, the renal masses were correctly identified with automatic AR technology, performing a successful enucleoresection. No intraoperative or postoperative Clavien >2 complications or positive surgical margins were recorded. Our pilot study provides the first demonstration of the application of computer vision technology for AR procedures, with a software automatically performing a visual concordance during the overlap of 3D models and in vivo anatomy. Its actual limitations, related to the kidney deformations during surgery altering the automatic anchorage, will be overcome implementing the organ recognition with deep learning algorithms.

Purpose: To evaluate the role of 3D models on positive surgical margin rate (PSM) rate in patients who underwent robot-assisted radical prostatectomy (RARP) compared to a no-3D control group. Secondarily, we evaluated the postoperative functional and oncological outcomes. Methods: Prospective study enrolling patients with localized prostate cancer (PCa) undergoing RARP with mp-MRI-based 3D model reconstruction, displayed in a cognitive or augmented-reality fashion, at our Centre from 01/2016 to 01/2020. A control no-3D group was extracted from the last two years of our Institutional RARP database. PSMr between the two groups was evaluated and multivariable linear regression (MLR) models were applied. Finally, Kaplan–Meier estimator was used to calculate biochemical recurrence at 12 months after the intervention. Results: 160 patients were enrolled in the 3D Group, while 640 were selected for the Control Group. A more conservative NS approach was registered in the 3D Group (full NS 20.6% vs 12.7%; intermediate NS 38.1% vs 38.0%; standard NS 41.2% vs 49.2%; p = 0.02). 3D Group patients had lower PSM rates (25 vs. 35.1%, p = 0.01). At MLR models, the availability of 3D technology (p = 0.005) and the absence of extracapsular extension (ECE, p = 0.004) at mp-MRI were independent predictors of lower PSMr. Moreover, 3D model represented a significant protective factor for PSM in patients with ECE or pT3 disease. Conclusion: The availability of 3D models during the intervention allows to modulate the NS approach, limiting the occurrence of PSM, especially in patients with ECE at mp-MRI or pT3 PCa.

Keywords: 3D modeling , Augmented reality , Prostate cancer , Robotic surgery , Surgical margins

Background: Tele-rehabilitation is gaining importance due to the increasing need for objectiveness in the evaluation of patients with impaired motor functions. Low-cost marker-less motion capture systems are becoming key enabling technologies as support in the treatment of musculoskeletal diseases. Objectives: The goal of this work is to investigate the use of the Microsoft Azure Kinect device to develop a tele-rehabilitation platform for shoulder motor function recovery. The platform comprehends a set of serious games, which are fundamental to increase the patients' engagement in shoulder rehabilitation. Methods: Starting from a set of functionalities identified together with the medical personnel of an Italian hospital, the Azure Kinect device has been used as motion capture system to interact with the serious games. Mobile applications for patients and physicians have been developed to manage the rehabilitation process. Results: The solution has been tested by the involved medical personnel. It has been considered interesting and promising. Further improvements in the design of the virtual environment of the serious games are required. Conclusion: The presented platform is a starting point to develop a complete IT solution for the daily shoulder rehabilitation.

Keywords: Rehabilitation research , Shoulder rehabilitation , Telerehabilitation , Virtual reality exposure therapy