3D Replicas Research Articles

Effects of functional endoscopic sinus surgery on the acoustics of the sinonasal tract

Nasal and paranasal cavities are supposed to contribute substantially to the vocal tract resonator properties. However, their acoustical effects as well as the effects of sinus surgery on the voice remain unclear. In this work we investigate resonance phenomena of paranasal sinuses prior to and after various rhinosurgical procedures in cadaveric human sinonasal tracts and corresponding 3D casts. Nasal and paranasal cavities of formalin-preserved cadavers and corresponding 3D replicas were excited by sine-tone sweeps from an earphone placed in the epipharynx. The response was picked up by a microphone at the nostrils. Different FESS procedures were performed and the acoustical responses following excitation were recorded. The measured acoustical changes in the obtained transfer functions were then evaluated. Marked low frequency dips were detected in the transfer functions when sinus cavities were included in the nasal resonator system. These dips showed a significant correlation with sinus volumes. Following FESS procedures they moved upwards in frequency depending on the extent of the surgical intervention. The transfer functions obtained in cadaveric situs and 3D replicas showed dips at the resonance frequencies of the paranasal cavities. Marked acoustic effects in terms of increase in dip frequency following FESS procedures were reproducibly documented.

Tunable multimodal adhesion of 3D, nanocrystalline CoFe2O4 pollen replicas

3D replicas of sunflower pollen microparticles, comprised of a multicomponent magnetic spinel ferrite (CoFe2O4) with tailorable adhesive properties, have been synthesized for the first time via a conformal layer-by-layer (LbL) surface sol–gel (SSG) deposition process followed by organic pyrolysis and oxide compound formation at a peak temperature of 600 °C–900 °C. These high-fidelity ferrite pollen replicas exhibited multimodal (van der Waals, vdW, and magnetic) adhesion that could be tuned via control of the CoFe2O4 nanoparticle and crystal sizes. The CoFe2O4 pollen replicas exhibited a non-monotonic change in short-range (~10 nm) vdW adhesion with an increase in the peak firing temperature, which was consistent with the counteracting effects of particle coarsening on the size and number of nanoparticles present on the sharp tips of the echini (spines) on the pollen replica surfaces. The longer-range (up to ~1 mm) magnetic force of adhesion increased monotonically with an increase in firing temperature, which was consistent with the observed increases in the values of the saturation and remanent magnetization of CoFe2O4 with an increase in average nanocrystal size. By adjusting the nanocrystal/nanoparticle sizes of the CoFe2O4 pollen replicas, the total force of adhesion (vdW + magnetic) to a magnetic substrate could be increased by a factor of ~3 relative to native pollen grains.

INTEGRATION OF 3D MODELS AND DIAGNOSTIC ANALYSES THROUGH A CONSERVATION-ORIENTED INFORMATION SYSTEM

Abstract. In the recent years, mature technologies for producing high quality virtual 3D replicas of Cultural Heritage (CH) artefacts has grown thanks to the progress of Information Technologies (IT) tools. These methods are an efficient way to present digital models that can be used with several scopes: heritage managing, support to conservation, virtual restoration, reconstruction and colouring, art cataloguing and visual communication. The work presented is an emblematic case of study oriented to the preventive conservation through monitoring activities, using different acquisition methods and instruments. It was developed inside a project founded by Lombardy Region, Italy, called “Smart Culture”, which was aimed to realise a platform that gave the users the possibility to easily access to the CH artefacts, using as an example a very famous statue. The final product is a 3D reality-based model that contains a lot of information inside it, and that can be consulted through a common web browser. In the end, it was possible to define the general strategies oriented to the maintenance and the valorisation of CH artefacts, which, in this specific case, must consider the integration of different techniques and competencies, to obtain a complete, accurate and continuative monitoring of the statue.

Four-Dimensional Phase Contrast Magnetic Resonance Imaging Protocol Optimization Using Patient-Specific 3-Dimensional Printed Replicas for InVivo Imaging Before and After Flow Diverter Placement.

Hemodynamics in cerebral aneurysms are currently investigated toward clinical efficacy using nonstandardized computational simulation techniques. At the same time, flow patterns and velocities are accessible by 4-dimensional phase contrast magnetic resonance imaging (4D pcMRI). Complexity of protocol design and imaging duration has limited the use of this technique in clinical imaging. A new approach is presented to overcome these limitations. Three-dimensional (3D) replicas of 2 cerebral aneurysms were fabricated by fused deposition prototyping (3D printing) and imaged using 4D pcMRI while connected to a magnetic resonance imaging-compatible continuous flow loop. Acquisition parameters were optimized with imaging times not to exceed 10 minutes. Six patients harboring cerebral aneurysms with sizes ranging from 4.7 to 13.8 mm were imaged with the optimized 4D pcMRI protocol. After treatment with the pipeline embolization device (PED), 4D pcMRI examinations were repeated in 3 patients. In all cases, major flow patterns were visualized well; smaller aneurysms posed a challenge because of limited spatial resolution, whereas larger aneurysms contained regions of low velocity resulting in limited contrast in the flow-sensitive images. After PED placement, ordered aneurysmal flow was disrupted and intra-aneurysmal velocity was reduced on average by 24.5% (range, 12.9-31.5%). Exploratory statistical analysis yielded a positive significant correlation (P < 0.01) between changes in inflow velocity and posttreatment intra-aneurysmal flow velocity. 4D pcMRI flow imaging in cerebral aneurysms within a time frame suitable for clinical imaging applications is feasible with optimized acquisition parameters, thereby enabling quantification of intra-aneurysmal flow changes after flow diverter device treatment.

From stucco to digital: Topometric documentation of Classic Maya facades at Holmul

This article addresses the use of a structured light 3d scanner to document ancient Maya architecture. A rationale for the project is outlined along with some practicalities of operating the equipment in remote locations and archaeological tunnels. The two case studies describe the documentation of painted stucco friezes at the archaeological site of Holmul, Guatemala, by the Corpus of Maya Hieroglyphic Inscriptions of the Peabody Museum of Archaeology and Ethnology, Harvard University. Holmul buildings boast some of the most elaborate and well-preserved stucco sculptures in the Maya world. The paper concludes with highlighting the current challenges in creating and using high-resolution 3d replicas for research and conservation purposes.

HAPTIC DEVICES AND TACTILE EXPERIENCES IN MUSEUM EXHIBITIONS

Museums all around the globe are starting to adopt advanced technologies that enable the visitors to interact with digital replicas of their collections and artworks. Immersive and interactive virtual reality applications represent one of the most appealing and most used technologies within modern museum exhibitions areas. Using these types of applications the visitors can have access to additional layers of information which can be presented in different languages and presented to the visitor when they demand it using advanced digital interactivity. But the major drawback of these applications is that they don’t allow the users to experience tactile exploration regarding the shapes and ornaments of the cultural heritage artefacts. People are programmed to gather and receive sensory information using their sight, hearing but also using tactile experiences. In order to enable tactile experiences within museum exhibitions, modern technologies such as haptic devices can be installed to enable the visitors to examine the shape of the 3D digital replicas of real artefacts. This paper presents a case study of a haptic device instalment within a museum exhibition that can enable real time tactile exploration of digitized artefacts.

Morphologic Assessment of the Left Atrial Appendage in Patients with Atrial Fibrillation by Gray Values–Inverted Volume-Rendered Imaging of Three-Dimensional Transesophageal Echocardiography: A Comparative Study with Computed Tomography

Accurate assessment of left atrial appendage (LAA) morphology is crucial in determining an LAA occlusion strategy. The aim of this study was to develop a novel echocardiographic volume-rendered imaging technique to visualize LAA morphology. This was a retrospective study. Forty patients with atrial fibrillation who underwent three-dimensional (3D) transesophageal echocardiography (TEE) and cardiac computed tomographic angiography (CCTA) before catheter ablation were enrolled. Full-volume 3D data were acquired and displayed in gray values-inverted (GVI) mode. Threshold segmentation and interactive segmentation were used to create 3D digital replicas of the LAA chambers. The morphologic classification, number of lobes, and dimensions of the LAA were analyzed and compared with the data obtained with CCTA. LAA morphology and measurements were successfully acquired via CCTA and 3D GVI TEE in all 40cases. In terms of LAA morphologic classifications, 19 cases of chicken wing, eight of windsock, nine of cauliflower, and four of cactus morphology were determined using 3D GVI TEE, and 20 cases of chicken wing, eight of windsock, eight of cauliflower, and four of cactus morphology were determined using CCTA. The κ value between these two methods was 0.963. Measurements of maximal diameter, minimal diameter, and area of the ostia and the depth of the LAAs were larger when based on the 3D GVI transesophageal echocardiographic data than when using cardiac computed tomographic angiographic data (P<.01); however, there was agreement between the results. Formed thrombi were well displayed by both computed tomography and 3DGVI TEE. Three-dimensional GVI TEE can be used to acquire LAA morphologic volume-rendered images that are similar to computed tomographic volume-rendered images, and it shows promise as a feasible and valuable modality for planning individual LAA occlusion procedures.

The Utility of Advanced Imaging in Forensic Anthropology.

Imaging technologies play an integral role in forensic anthropology cases. Advances in digital photography allow the anthropologist to photo-document the scene and skeletal remains in exceptional detail. Traditionally, radiographs have been used to document remains, potential trauma, and any individualizing characteristics such as healing trauma and frontal sinus morphology. Given technological advances, some forensic anthropologists have begun to incorporate more advanced imaging methods in their case analyses and research, such as computed tomography and three-dimensional (3D) surface scans. These advanced imaging technologies provide a means to document skeletal remains and trauma, and can be used to create 3D replicas of the elements for archival and illustrative purposes. Researchers have begun to develop novel methods for estimating biological parameters from these 3D virtual models, using new variables such as surface areas and volumes, and advanced statistical methods (e.g., geometric morphometric analyses) to quantitatively analyze skeletal variation for sex and ancestry estimation. The use of these technologies in forensic anthropology remains somewhat limited, however, due to required costs, expertise, and the time involved in collecting and processing the data. Newly developed methods require further validation, and some areas of advanced imaging, such as photogrammetry, remain relatively unexplored in the field. Interdisciplinary collaborations between forensic anthropologists and other medicolegal professionals can help alleviate some of these resource constraints and facilitate advancements in forensic case analysis and research.

3D Printed Models of Cleft Palate Pathology for Surgical Education.

Objective:To explore the potential viability and limitations of 3D printed models of children with cleft palate deformity.Background:The advantages of 3D printed replicas of normal anatomical specimens have previously been described. The creation of 3D prints displaying patient-specific anatomical pathology for surgical planning and interventions is an emerging field. Here we explored the possibility of taking rare pediatric radiographic data sets to create 3D prints for surgical education.Methods:Magnetic resonance imaging data of 2 children (8 and 14 months) were segmented, colored, and anonymized, and stereolothographic files were prepared for 3D printing on either multicolor plastic or powder 3D printers and multimaterial 3D printers.Results:Two models were deemed of sufficient quality and anatomical accuracy to print unamended. One data set was further manipulated digitally to artificially extend the length of the cleft. Thus, 3 models were printed: 1 incomplete soft-palate deformity, 1 incomplete anterior palate deformity, and 1 complete cleft palate. All had cleft lip deformity. The single-material 3D prints are of sufficient quality to accurately identify the nature and extent of the deformities. Multimaterial prints were subsequently created, which could be valuable in surgical training.Conclusion:Improvements in the quality and resolution of radiographic imaging combined with the advent of multicolor multiproperty printer technology will make it feasible in the near future to print 3D replicas in materials that mimic the mechanical properties and color of live human tissue making them potentially suitable for surgical training.

Porcine liver vascular bed in Biodur E20 corrosion casts.

Pigs are frequently used as animal models in experimental medicine. To identify processes of vascular development or regression, vascular elements must be recognised and quantified in a three-dimensional (3D) arrangement. Vascular corrosion casts enable the creation of 3D replicas of vascular trees. The aim of our study was to identify suitable casting media and optimise the protocol for porcine liver vascular corrosion casting. Mercox II® (Ladd Research, Williston, Vermont, USA) and Biodur E20® Plus (Biodur Products, Heidelberg, Germany) were tested in 4 porcine livers. The resins (volume approximately 700 mL) were injected via the portal vein. Corrosion casts were examined by macro-computed tomography, micro-computed tomography and scanning electron microscopy. For hepatectomies, the operating protocol was optimised to avoid gas or blood clot embolisation. We present a protocol for porcine liver vascular bed casting based on corrosion specimens prepared using Biodur E20® epoxy resin. Only Biodur E20®Plus appeared to be suitable for high-volume vascular corrosion casting due to its optimal permeability, sufficient processing time and minimum fragility. Biodur E20® Plus is slightly elastic, radio-opaque and alcohol-resistant. These properties make this acrylic resin suitable for not only vascular research but also teaching purposes.

3D scanning and printing skeletal tissues for anatomy education.

Detailed anatomical models can be produced with consumer-level 3D scanning and printing systems. 3D replication techniques are significant advances for anatomical education as they allow practitioners to more easily introduce diverse or numerous specimens into classrooms. Here we present a methodology for producing anatomical models in-house, with the chondrocranium cartilage from a spiny dogfish (Squalus acanthias) and the skeleton of a cane toad (Rhinella marina) as case studies. 3D digital replicas were produced using two consumer-level scanners and specimens were 3D-printed with selective laser sintering. The fidelity of the two case study models was determined with respect to key anatomical features. Larger-scale features of the dogfish chondrocranium and frog skeleton were all well-resolved and distinct in the 3D digital models, and many finer-scale features were also well-resolved, but some more subtle features were absent from the digital models (e.g. endolymphatic foramina in chondrocranium). All characters identified in the digital chondrocranium could be identified in the subsequent 3D print; however, three characters in the 3D-printed frog skeleton could not be clearly delimited (palatines, parasphenoid and pubis). Characters that were absent in the digital models or 3D prints had low-relief in the original scanned specimen and represent a minor loss of fidelity. Our method description and case studies show that minimal equipment and training is needed to produce durable skeletal specimens. These technologies support the tailored production of models for specific classes or research aims.

Characterizing, Designing, and Selecting Metal Mesh Screens for Standalone-Screen Applications

Summary Discrete-element-method (DEM) simulations were shown to be useable for selecting screens with simple geometries (e.g., wire-wrap screens) under prepack test conditions (Mondal et al. 2011). Metal mesh screens (MMSs) (commonly referred to as premium screens) can have multiple (sometimes sintered) layers with different weave patterns. Any model for estimating sand production in such screens must account for these complexities. The objective of this paper is to explore different techniques to create accurate representations of complex filter media and to use them in numerical simulations and/or analytical models for improved screen selection. In this paper, we used computed-tomography (CT) images of real-screen coupons to construct 3D replicas of two MMS types: plain square mesh (PSM) and plain Dutch weave (PDW). An entirely computer-based method of creating 3D screen assemblies is also presented. These virtual screens were compared and validated against those generated from the CT images. We conducted DEM simulations of prepack tests through these multilayer MMS assemblies. The retention efficiency of MMSs for different particle sizes was also calculated for better slurry-test modeling. We quantitatively showed that the effective size of MMS assemblies can be significantly lower than the nominal rating of the filter layer. This paper augments the prepack-test and slurry-test models for mesh-type screens presented earlier (Mondal et al. 2012; Chanpura et al. 2013). Determination of the retention efficiency of MMSs, which is currently characterized by a single filter-cut point, is also a step forward in quality assurance and quality control of these screens. Finally, we demonstrate that one can conduct in-depth screen design and optimization studies with virtual meshes in a consistent way and at a fraction of the cost and time that would be required otherwise by use of conventional experimental techniques.

Towards the definition of best 3D practices in archaeology: Assessing 3D documentation techniques for intra-site data recording

Archaeology is becoming increasingly ‘digital’. In the last 10 years, the use of 3D technologies for the documentation of tangible cultural heritage has changed the way to approach archaeological intra-site survey. These technologies allow for the reproduction of 3D replicas of sites and monuments and have proven to be a powerful tool for the documentation and preservation of the archaeological record. However, the full integration of 3D technologies in archaeological field methods requires the definition of best documentation practices and methods of accurate assessment of the acquired data. In fact, although the use of 3D laser scanners, computer vision and photogrammetric methods is now well established, there are no convincing quantitative comparisons between laser scanning and image-based modelling techniques for the acquisition of archaeological stratigraphy in extreme environmental and lighting conditions. In this sense the 3D documentation of the archaeological site of Las Cuevas, Belize, represented an important opportunity to test and compare phase shift variation laser scanning and image-based modelling techniques in an environment characterized by very high humidity and variability in lighting. This study compared both the accuracy and density reliability of 3D models showing how the different 3D documentation techniques can be integrated for the recording of the excavation process. The research presented in this paper provides an accurate data assessment representing a concrete starting point for the definition of a sharable and overall methodology that will help to define best 3D practices for the documentation of archaeological sites.

3D-ICONS: Digitizing Cultural Heritage Structures

As a partner in the EU co-funded 3D-ICONS project, the Discovery Programme has surveyed a wide range of the iconic cultural heritage sites in Ireland. This project aimed to establish a complete pipeline for the production of 3D replicas of archaeological monuments and historic buildings, and to publish the content to Europeana for public access. Challenges discussed include: making such high resolution data sets available to the public to enable online interaction and via the web, creating suitable and representative metadata and IPR frameworks for 3D cultural heritage data.

Comparing 2D pictures with 3D replicas for the digital preservation and analysis of tangible heritage

In this paper, we present two experiments designed to compare 2D digital pictures and 3D digital replicas of artifacts, to understand how differently these media facilitate the perception and understanding of our past. Archeologists and museum experts have commonly used 2D digital pictures to preserve and study artifacts. Recently, these scholars have also started to use 3D digital archives for their studies. Yet, we still need to determine how these two formats (2D vs. 3D) affect the perception of our past. Results of our experiments point to 3D digital replicas of artifacts as more effective means to digitally preserve tangible cultural heritage, since 3D multi-visualization augments the perception of physical characteristics of the artifacts allowing a more embodied experience with these objects. Our experiments also suggest that multi-visualization (i.e., point-cloud, mesh, and color information) helps the viewers to overcome their personal conceptualization of specific objects.

3D printed cardiovascular models for surgical planning in complex congenital heart diseases

Background A precise understanding of the anatomical structures of the heart and great vessels is essential for surgical planning in order to avoid unexpected findings. Rapid prototyping techniques are used to print three-dimensional (3D) replicas of patients’ cardiovascular anatomy based on 3D clinical images such as MRI. The purpose of this study is to explore the use of 3D patient-specific cardiovascular models using rapid prototyping techniques to improve surgical planning in patients with complex congenital heart disease.

Free and constrained amorphous phases in polyethylene: Interpretation of 1H NMR and SAXS data over a broad range of crystallinity

Polyethylene (PE) is available in various grades ranging from high-density to very-low density (co-)polymers. The morphology of PE strongly influences its properties and is extensively studied, including the content of phases. Most studies are usually concerned only with the crystallinity and non-critically adopt the classical three-component model of PE, which considers a crystalline (rigid) and an amorphous (mobile) phase separated by an interfacial (semi-rigid) component. We provide evidence that this assignment of the semi-rigid and mobile components can be incorrect at lower PE densities. The phase composition of industrial PE samples with crystallinities from 35 to 82 wt. % was studied using low-field 1H NMR and the characteristic dimensions of the lamellar stacks were measured using small-angle X-ray scattering (SAXS). Based on our results, we propose a new interpretation of PE morphology at crystallinities below 60 wt. %, which considers the rigid crystalline phase, the constrained (semi-rigid) amorphous phase inside the lamellar stacks and the free (mobile) amorphous phase outside the stacks. Interfacial chain segments are also present, but not detected as a separate component. Moreover, experimental data are compared with model predictions based on reconstructed 3D replicas of PE spherulites and an excellent agreement in the phase content is obtained. Our findings are important for the estimation of application properties (e.g., effective diffusivity), which strongly depend on the spatial distribution of the amorphous and crystalline phases.

Demonstration of protocol for computer-aided forensic facial reconstruction with free software and photogrammetry

Purpose: Forensic facial reconstruction (FFR) is an auxiliary technique that approximates a face in order to generate identifications. Technological development allows access to open software that can be applied to FFR. The demonstrated protocol has features from creating 3D replicas of the skull to finishing and displaying the reconstruction. PPT GUI is used for 3D scanning, and the resulting point cloud is converted into a 3D mesh in MeshLab. The sculpture is made in Blender, according to the user’s preferred technique. The adaptation of the skin layer and finishing of the reconstruction is optimized with the use of templates. In this phase, details can also be hand-carved. Allied to basic training in the software featured in this protocol, the open access to these tools and its independence of imaging hardware other than digital cameras is an advantage to its application in forensic and research contexts.

Development and Three-Dimensional Morphology of the Zygomaticotemporal Suture in Primate Skulls

Cranial sutures are an essential part of the growing skull, allowing bones to increase in size during growth, with their morphology widely believed to be dictated by the forces and displacements that they experience. The zygomaticotemporal suture in primates is located in the relatively weak zygomatic arch, and externally it appears a very simple connection. However, large forces are almost certainly transmitted across this suture, suggesting that it requires some level of stability while also allowing controlled movements under high loading. Here we examine the 2- and 3-dimensional (3D) morphology of the zygomaticotemporal suture in an ontogenetic series of Macaca fascicularis skulls. High resolution microcomputed tomography data sets were examined, and virtual and physical 3D replicas were created to assess both structure and general stability. The zygomaticotemporal suture is much more complex than its external appearance suggests, with interlocking facets between the adjacent zygomatic and temporal bones. It appears as if some movement is permitted across the suture in younger animals, but as they approach adulthood the complexity of the suture's interlocking bone facets reaches a level where these movements become minimal.

3D Printing of an Aortic Aneurysm to Facilitate Decision Making and Device Selection for Endovascular Aneurysm Repair in Complex Neck Anatomy

To describe rapid prototyping or 3-dimensional (3D) printing of aneurysms with complex neck anatomy to facilitate endovascular aneurysm repair (EVAR). A 75-year-old man had a 6.6-cm infrarenal aortic aneurysm that appeared on computed tomographic angiography to have a sharp neck angulation of ~90°. However, although the computed tomography (CT) data were analyzed using centerline of flow, the true neck length and relations of the ostial origins were difficult to determine. No multidisciplinary consensus could be reached as to which stent-graft to use owing to these borderline features of the neck anatomy. Based on past experience with rapid prototyping technology, a decision was taken to print a model of the aneurysm to aid in visualization of the neck anatomy. The CT data were segmented, processed, and converted into a stereolithographic format representing the lumen as a 3D volume, from which a full-sized replica was printed within 24 hours. The model demonstrated that the neck was adequate for stent-graft repair using the Aorfix device. Rapid prototyping of aortic aneurysms is feasible and can aid decision making and device delivery. Further work is required to test the value of 3D replicas in planning procedures and their impact on procedure time, radiation dose, and procedure cost.