Use Of Three-dimensional Models Research Articles

Validation of a new radiographic protocol for Asian elephant feet and description of their radiographic anatomy

Foot problems are extremely common in elephants and radiography is the only imaging method available but the radiographic anatomy has not been described in detail. The aims of this study...

Clinical use of three-dimensional models of the temporomandibular joint established by rapid prototyping based on cone-beam computed tomography imaging data

Three-dimensional rapid prototyping (3D RP) models based on volumetric image data acquired by various modalities have been used in presurgical planning, implant design, and medical education. To the best of our knowledge, cone-beam computed tomography (CBCT) is the best modality for imaging bone components of the temporomandibular joint (TMJ). 3D RP models of the TMJ are also applied for reconstruction design, simple anatomical evaluation, and education. Although 3D RP models of the TMJ already provide much information during preoperative and anatomical evaluation, we intended to expand the utility of these models. This paper presents two examples of the application of 3D RP models of the TMJ based on CBCT imaging data and briefly reviews the usage of 3D RP models.

Cochlear structural variants in echolocators

Although microchiropteran bats and odontocete cetaceans operate in radically different media, both have sophisticated sonar capabilities and evident similarities in their ability to detect and analyze ultrasonic signals. This paper compares the similarities and differences of cochlear cytoarchitecture and its implications for ultrasonic encoding and acuity amongst these groups through the use of three-dimensional models obtained via micro-CT imaging of intact heads and temporal bones. Inner ear anatomy was fundamentally similar with notable parallels in fenestral placement and ratios, membrane dimensions, and neural density and distribution across bats and dolphins with common cochlear types. Specialist ears are present in both groups, suggesting that like some CF-CM bats, one or more odontocete species have cochleae with specialized basilar membrane “foveal” regions. Cochlear specializations in both groups are primarily linked to peak spectra of signal, expanded frequency representation, and may enhance tuning in adjacent ear segments by generating standing wave phenomena. [Supported by N45- US Navy Environmental Division and the Office of Naval Research]

Medical rapid prototyping (MRP) in adult- and paediatric cardiac surgery

Aims: Medical rapid prototyping (MRP) enables the fabrication of three-dimensional models, demonstrating the human anatomy. Currently, we demonstrate the use of three-dimensional models for complex anatomical situations in cardiaovascular surgery.

Two-Dimensional Glenoid Version Measurements Vary with Coronal and Sagittal Scapular Rotation

Accurate analysis of osseous glenoid morphology is important in treating glenohumeral arthritis and instability. Two-dimensional computed tomography scans are used to evaluate glenoid alignment. Accuracy of this method is dependent on the angle of axial reconstruction in relation to the position of the scapula. The purpose of this study was to investigate the effect of scapular rotation in the coronal and sagittal planes on glenoid version as measured on two-dimensional images. Computer-generated three-dimensional models of scapulae from computed tomography scans of thirty-six shoulders in whole-body cadavers were generated. The anatomic geometry of these models had been previously validated. The position of the scapulae relative to the gantry was determined. The three-dimensional models were rotated in 1 degree increments in the coronal and sagittal planes. Glenoid version was measured on two-dimensional images for each of the rotation increments. Version variability at each rotation increment was calculated. The anatomic glenoid version (independent of the resting position of the scapula) was an average (and standard deviation) of 2.0 degrees +/- 3.8 degrees of retroversion. The average difference between anatomic glenoid version and clinical glenoid version (depending on the position of the scapula on the original computed tomography axial images) was 6.9 degrees +/- 5.6 degrees (range, 0.1 degrees to 22.5 degrees). Version variability with coronal or sagittal rotation was significant for all degrees of rotation (p < 0.0001). Scapular abduction had the greatest effect on version variation and resulted in 0.42 degrees of relative anteversion for every 1 degree of abduction in the coronal plane. In the sagittal plane, internal rotation resulted in relative anteversion. Any malalignment of > or = 1 degree of the scapula in the coronal or sagittal plane will create inaccuracies in measuring glenoid version. The plane of axial reconstruction should be aligned with the scapula when two-dimensional computed tomography images are used to measure glenoid version. These findings support the use of three-dimensional models to evaluate glenoid version.

Hybrid 3D pregnant woman and fetus modeling from medical imaging for dosimetry studies

Numerical simulations studying the interactions between radiations and biological tissues require the use of three-dimensional models of the human anatomy at various ages and in various positions. Several detailed and flexible models exist for adults and children and have been extensively used for dosimetry. On the other hand, progress of simulation studies focusing on pregnant women and the fetus have been limited by the fact that only a small number of models exist with rather coarse anatomical details and a poor representation of the anatomical variability of the fetus shape and its position over the entire gestation. In this paper, we propose a new computational framework to generate 3D hybrid models of pregnant women, composed of fetus shapes segmented from medical images and a generic maternal body envelope representing a synthetic woman scaled to the dimension of the uterus. The computational framework includes the following tasks: image segmentation, contour regularization, mesh-based surface reconstruction, and model integration. A series of models was created to represent pregnant women at different gestational stages and with the fetus in different positions, all including detailed tissues of the fetus and the utero-fetal unit, which play an important role in dosimetry. These models were anatomically validated by clinical obstetricians and radiologists who verified the accuracy and representativeness of the anatomical details, and the positioning of the fetus inside the maternal body. The computational framework enables the creation of detailed, realistic, and representative fetus models from medical images, directly exploitable for dosimetry simulations.

Innovative research and development based on of 3D parametric modeling technology

The paper presents the results of innovative research and development based on of 3D parametric modeling technology. Due to the time-saving for R&amp;D, the use of three-dimensional models makes it possible to hasten the preproduction process and to increase the competitive ability of new products. Some examples of the developed projects are presented.

A scatter search-based technique for pair-wise 3D range image registration in forensic anthropology

Different tasks in forensic anthropology require the use of three-dimensional models of forensic objects (skulls, bones, corpses, etc) captured by 3D range scanners. Since a whole object cannot be completely scanned with a single image, multiple scans from different views are needed to supply the information to construct the 3D model. Range image registration methods study the accurate integration of the different views acquired by range scanners, with pair-wise approaches progressively processing every adjacent pair of scanned views until reconstructing the whole 3D model of the object. Our proposal is based on the adaptation of our previous work (Cordon et al, IEEE Conference on Evolutionary Computation, pp 2738–2744, 2005 in Pattern Recognit Lett 27(11); 1191-1200, 2006) in order to apply the scatter search evolutionary algorithm to pair-wise image registration in forensic anthropology applications. To measure the performance of this adaptation, we design an experimental setup considering some of the most recent and accurate evolutionary techniques for the problem, as well as one skull from our Physical Anthropology Lab. Two additional volumes, commonly used in other pair-wise range IR contributions, have also been considered to complement the comparison of results among the proposals.

Superposition of borehole-to-surface voltage residuals for Vadose Zone plume delineation

An injected tracer field experiment was conducted at the University of Idaho Ground Water Field Laboratory to evaluate the application of borehole-to-surface voltage measurements for delineation of the tracer distribution in partially saturated, fractured basalt. A tap water tracer was injected into a fracture-dominated, salt-water plume formed during a previous salt-water injection experiment. The tap water tracer was injected into a central injection well under constant hydraulic head for 34 days. The injection well was surrounded by seven test boreholes. Each borehole contained several copper wire electrodes for borehole-to-surface potential measurements between a surface grid of 224 copper sulfate, porous pot electrodes. Eight pole–pole, borehole-to-surface voltage data sets were acquired during each measurement period by energization of a selected electrode in each of the eight boreholes. Predicted voltages for a uniform earth (homogeneous and isotropic) potential model (finite difference) were subtracted from each data set (for its respective current source location), and the voltage residuals superposed to create new data sets with greater measurement sensitivity and coverage, to aid in interpretation. These data sets were collected over four measurement periods during tap water injection and four measurement periods during the subsequent 64-day drainage phase. The data were interpreted with the use of three-dimensional models and by comparisons with other electrical and hydrological observations. Results indicate that superposition of multiple data sets of voltage residuals significantly improved the lateral resolution of subsurface bulk resistivity changes that occurred over time.

The use of a three-dimensional imaging model to optimize the operative separation of pygopagus conjoined twins

Introduction The surgical management of conjoined twins has evolved to the point that elective operative separation can safely be performed in the majority. Cross-sectional imaging is invaluable to accurately delineate the site of union and configuration of shared organ systems prior to surgery. The use of three-dimensional modeling also dramatically improves the planning process and assists in intraoperative decision-making. We present a case of pygopagus conjoined twins who underwent successful operative separation at 19 months of age with the aid of such technology. Methods A three-dimensional computer animation was created by Medical Modeling LLC (Golden, CO, USA) from representative cross-sectional CT and MR images. The complete animation is available at http// www.medicalmodeling.com/ahmed. A plasticized bony pelvic model, accurate to 1 mm, was also created using similar technology. Results The three-dimensional animation and pelvic model were utilized during both the planning and operative phases of the separation. The shared pelvic soft-tissue anatomy consisted of a conjoined penis with four corporal bodies, and a posteriorly conjoined urethra subtending two separate bladders and outlets. The rectum was conjoined approximately 2 cm proximal to the single anus. A blind-ending hindgut remnant was also documented by the animation. Following operative separation, both twins recovered uneventfully. Conclusions Three-dimensional computer animation technology was extremely accurate intraoperatively and predicted exactly which shared organs would sequentially be encountered as the dissection commenced. It significantly reduced the overall operative time and provided critical intraoperative anatomic information. We recommend that this readily available technology be utilized for any patient requiring extensive reconstructive surgery.

Pupils\' Drawings of What is Inside Themselves: A Case Study in Zimbabwe

This preliminary study looks at the understandings, as revealed by their drawings, of some seven-year-olds and 15-year-olds in Zimbabwe of their internal anatomy. A total of 23 seven year-olds and 21 fifteen year-olds participated in the study. These pupils were given a blank piece of A4-sized (296 x 210 mm) drawing paper and asked to draw what they thought was inside themselves. The drawings were analysed on a seven point scale related to biological knowledge of human organs and organ systems. The results show that the older pupils had a greater knowledge of their internal anatomy but that there was no relationship between gender and biological knowledge. Some organ systems - the gaseous exchange system, the digestive system, the circulatory system, the skeletal system, the urinogenital system and the nervous system, were statistically more likely to have organs drawn from them than were others such as the endocrine system and the muscular system. Recommendations are made for biology teaching which would help improve understanding in this area. In particular, when introducing human anatomy to pupils, teachers could begin with individual organs and then help pupils appreciate that these organs exist as functional units within organ systems. This could be done by the use of three-dimensional models or by assembling two-dimensional organ systems from cut organ system diagrams.

Magnetic fields dispersed by high-voltage power lines: an advanced evaluation method based on 3-D models of electrical lines and the territory

An advanced numerical evaluation tool is proposed for calculating the magnetic flux density dispersed by high-voltage power lines. When compared to existing software packages based on the application of standardized methods, this tool turned out to be particularly suitable for making accurate evaluations on vast portions of the territory, especially when the contribution of numerous aerial and/or underground lines must be taken into account. The aspects of the tool of greatest interest are (1) the interaction with an electronic archive of power lines, from which all the information necessary for the calculation is obtained; (2) the use of three-dimensional models of both the power lines and the territory crossed by these; (3) the direct interfacing with electronic cartography; and finally (4) the use of a representation procedure for the results that is based on contour maps. The tool had proven to be very useful especially for Environmental Impact Assessment procedures relative to new power lines.

Analysis of differential substrate selectivities of CYP2B6 and CYP2E1 by site-directed mutagenesis and molecular modeling.

Human CYP2B6 and CYP2E1 were used to investigate the extent to which differential substrate selectivities between cytochrome P450 subfamilies reflect differences in active-site residues as opposed to distinct arrangement of the backbone of the enzymes. Reciprocal CYP2B6 and CYP2E1 mutants at active-site positions 103, 209, 294, 363, 367, and 477 (numbering according to CYP2B6) were characterized using the CYP2B6-selective substrate 7-ethoxy-4-trifluoromethylcoumarin, the CYP2E1-selective substrate p-nitrophenol, and the common substrates 7-ethoxycoumarin, 7-butoxycoumarin, and arachidonic acid. This report is the first to study the active site of CYP2E1 by systematic site-directed mutagenesis. One of the most intriguing findings was that substitution of CYP2E1 Phe-477 with valine from CYP2B6 resulted in significant 7-ethoxy-4-trifluoromethylcoumarin deethylation. Use of three-dimensional models of CYP2B6 and CYP2E1 based on the crystal structure of CYP2C5 suggested that deethylation of 7-ethoxy-4-trifluoromethylcoumarin by CYP2E1 is impeded by van der Waals overlaps with the side chain of Phe-477. Interestingly, none of the CYP2B6 mutants acquired enhanced ability to hydroxylate p-nitrophenol. Substitution of residue 363 in CYP2E1 and CYP2B6 resulted in significant alterations of the metabolite profile for the side chain hydroxylation of 7-butoxycoumarin. Probing of CYP2E1 mutants with arachidonic acid indicated that residues Leu-209 and Phe-477 are critical for substrate orientation in the active site. Overall, the study revealed that differences in the side chains of active-site residues are partially responsible for differential substrate selectivities across cytochrome P450 subfamilies. However, the relative importance of active-site residues appears to be dependent on the structural similarity of the compound to other substrates of the enzyme.

Liquid crystal measurements of heat transfer and surface shearstress

Liquid crystals have become an accurate and convenient means ofmeasuring surface temperature and heat transfer for the gas turbine andheat transfer research communities. The measurement of surface shear stressusing liquid crystals is finding increasing favour with aerodynamicists anddevelopments in these techniques ensure that liquid crystals will continueto provide key thermal and shear stress data in the future. The increasing useof three-dimensional finite element computational models has allowedindustry to capitalize on the advantages of the full surface datagenerated. The paper reviews the use of these complex materials in researchwith a special emphasis on recent developments in the field. The aim is toprovide the reader with an up to date background in this measurementtechnology and allow the researcher to decide whether liquid crystals wouldbe suitable in specific applications.

Computer planning for distraction osteogenesis.

Distraction osteogenesis of the mandible has found an application in the treatment of patients with a variety of different mandibular deformities. Compared with the relatively simple unidirectional distraction of long bones as described by Ilizarov, the three-dimensional distraction of the mandible is extremely complex. Whereas experience with orthognathic surgery clearly demonstrates that careful presurgical planning is necessary to achieve predictable outcomes, there are few reported methods for the planning of mandibular distraction. The authors have developed a method for planning distraction osteogenesis of the mandible that involves the use of three-dimensional modeling and animation to simulate distraction osteogenesis in virtual reality. The first step in the authors' treatment planning process is to obtain a three-dimensional computerized scan of the facial skeleton. From this scan, a three-dimensional wire-mesh model is built using animation software. With the same software, a virtual distractor is built and installed on the wire-mesh model. The osteotomies and the distraction process are then simulated. Finally, a recipe for sequencing the linear and angular changes of the distractor is calculated. The authors have used this planning process in seven patients (age range, 4 to 10 years): four with unilateral mandibular deformities and three with bilateral. The planning process has yielded predictable and reproducible results.

Numerical methods for the solution of the turbulence energy equations in shelf seas

This paper investigates the accuracy of numerical finite difference methods for solving the turbulence kinetic energy equations in thermally stratified shelf seas with wind and tidal mixing. Alternative discretisation methods are presented for both the source terms and the diffusion term in the turbulence kinetic energy equation. It is shown that techniques not widely used in this field maintain greater accuracy at low spatial and temporal resolution than is obtained with commonly used ones, with no added computational cost. Therefore, these techniques are valuable for use in three-dimensional models. Copyright © 1999 John Wiley & Sons, Ltd.

Numerical methods for the solution of the turbulence energy equations in shelf seas

This paper investigates the accuracy of numerical finite difference methods for solving the turbulence kinetic energy equations in thermally stratified shelf seas with wind and tidal mixing. Alternative discretisation methods are presented for both the source terms and the diffusion term in the turbulence kinetic energy equation. It is shown that techniques not widely used in this field maintain greater accuracy at low spatial and temporal resolution than is obtained with commonly used ones, with no added computational cost. Therefore, these techniques are valuable for use in three-dimensional models. Copyright © 1999 John Wiley & Sons, Ltd.

Three-dimensional effects of hydraulic conductivity enhancement and desaturation around mined panels

Changes in the three-dimensional hydraulic conductivity field that accompany undermining by a longwall panel are evaluated to define the potential for changes in flow patterns and desaturation. Relations linking changes in conductivity with the mining-induced strain field that develops around the advancing face are defined through the assumption of an equivalent porous medium with the strain partition between fractures and matrix apportioned relative to respective deformation constants. Model results are validated against behavior recorded at a well instrumented field site, replicating the complex steady flow pattern that develops around an advancing longwall face. Significant hydraulic conductivity increases are restricted to strata at shallow depth, ahead of the advancing face, and to deep zones behind the face, particularly in the caving zone and abutment shear zones. These very large increases in conductivity at depth, that include the out-of-section conductivity enhancement that develops along the panel rib, exercise primary control on induced water level changes and the potential for saturation. Zones of desaturation are readily defined, with these enabling locations of well vulnerability (to water loss) to be identified. These zones of vulnerability are directly above the panel, with their extent potentially modulated by the presence and the location of flatlying layers of low conductivity. The complex response recorded in the near-face region mandates use of three-dimensional models to adequately represent observed behavior.

Stress analysis and strength prediction of mechanically fastened joints in FRP: a review

A review of the investigations that have been made on the stress and strength analysis of mechanically fastened joints in fibre-reinforced plastics (FRP) is presented. The experimental observations of the effects of joint geometry, ply-orientation, lay-up and through-thickness pressure on the joint behaviour are described briefly for both single and multi-fastener joints. The analytical and numerical methods of stress analysis required before trying to predict failure are discussed. The numerical approaches cover both two and three-dimensional models and the effects of clearance, friction and geometry are assessed. The several methods that have been used to predict failure in single or multi-fastener joints are described. It is concluded that there are some issues that require further investigation. There is no general agreement about the method that should be used to predict failure, but progressive damage models are quite promising since important aspects of the joint's behaviour can be modelled using this approach. In order to take into consideration several factors related to joint strength the use of three-dimensional models is suggested. These models require a three-dimensional failure criterion and an appropriate property degradation law.

Improved agreement of foot segmental power and rate of energy change during gait: Inclusion of distal power terms and use of three-dimensional models

Traditional models used to calculate foot segmental power have yielded poor agreement between foot power and the rate of energy change during the stance phase of gait and limited the applicability of foot segmental power analyses to swing phase only. The purpose of this study was to improve the agreement of foot segemental power and rate of energy change by using more inclusive models to calculate foot segmental power and energy. The gait of 15 adult subjects was studied and models were used to calculate foot segmental power that included either the proximal terms only (Model P, the most common method in the literature) or both proximal and distal terms (Model PD, a mathematically complete model). Power and energy terms were computed in to ways, from sagittal plane vector components only (two-dimensional condition) and from complete three-dimensional components (three-dimensional condition). Results revealed that the more inclusive the model, the higher the agreement of foot power and rate of energy change. During stance phase, Model P produced poor agreement ( r c = 0.108) for both two-dimensional and three-dimensional conditions, Model PD-2D yielded higher agreement ( r c = 0.645), and Model PD-3D exhibited nearly perfect agreement ( r c = 0.956). The advantages of a segmental power analysis include the ability to identify the mechanisms of energy transfer into and out of the foot during movement. The results of this study suggest that foot power analyses are valid when using Model PD-3D to describe foot function during locomotion.