Artificial Deformation Research Articles

In-Situ Systematic Error Correction for Digital Volume Correlation Using a Reference Sample

The self-heating effect of a laboratory X-ray computed tomography (CT) scanner causes slight change in its imaging geometry, which induces translation and dilatation (i.e., artificial displacement and strain) in reconstructed volume images recorded at different times. To realize high-accuracy internal full-field deformation measurements using digital volume correlation (DVC), these artificial displacements and strains associated with unstable CT imaging must be eliminated. In this work, an effective and easily implemented reference sample compensation (RSC) method is proposed for in-situ systematic error correction in DVC. The proposed method utilizes a stationary reference sample, which is placed beside the test sample to record the artificial displacement fields caused by the self-heating effect of CT scanners. The detected displacement fields are then fitted by a parametric polynomial model, which is used to remove the unwanted artificial deformations in the test sample. Rescan tests of a stationary sample and real uniaxial compression tests performed on copper foam specimens demonstrate the accuracy, efficacy, and practicality of the presented RSC method.

Análisis bioarqueológico de los restos de arroyo El Siasgo, (supuesto Homo caputinclinatus de Ameghino 1910)

Las investigaciones arqueológicas desarrolladas en la Depresión del río Salado durante las últimas tres décadas permitieron profundizar en el conocimiento de los grupos prehispánicos que vivieron allí durante el Holoceno tardío. Como resultado de los trabajos de campo en la microrregión, se conocen tres sitios con restos humanos (La Guillerma Ñandú, La Guillerma 1 y La Guillerma 5), totalizando un número mínimo de seis individuos inhumados de manera aislada. En esta contribución se suma, a la información precedente, el primer estudio bioarqueológico de un esqueleto recuperado por Carlos Ameghino en el arroyo El Siasgo a principios del siglo XX. El objetivo es presentar los resultados del análisis bioarqueológico de este esqueleto, así como el fechado radiocarbónico obtenido. Se busca así aportar a la revisión de un caso de singular importancia histórica a través de la aplicación de un marco teórico y metodológico renovado. Como resultado de los análisis bioarqueológicos se pudo establecer que los restos corresponden a un individuo juvenil, de entre 12 y 15 años, que habría sido inhumado en posición primaria y que presentaba el cráneo deformado de manera circular. Se obtuvo, para este esqueleto, un fechado de ca. 3500 años AP, que es el más antiguo para la depresión del río Salado. Los análisis isotópicos reflejan que la dieta del individuo fue mixta e incluyó la ingesta, en pequeñas cantidades, de alimentos marinos. Finalmente, estos resultados son integrados a la información bioarqueológica disponible para el área.

Assessing cranial plasticity in humans: The impact of artificial deformation on masticatory and basicranial structures

Artificial cranial deformations (ACD) are a widespread cultural practice found in numerous historical and prehistoric contexts. Their study can yield valuable insight into craniofacial growth, specifically into the interactions between neurocranial and basicranial modules. This study seeks to reinvestigate the presumed effect of ACD on basicranial and masticatory elements by applying a 3D geometric morphometric approach to CT scans. A total of 51 French and Bolivian skulls, representing anteroposterior and circumferential deformations and including undeformed individuals, were scanned, and 3D landmarks were submitted to between-group principal components analysis and two-block partial least-squares analysis. Our results illustrate changes in basicranial shape and in cranial base angles induced by ACD, as well as in masticatory geometry, namely in the relative position of the mandibular fossae. Furthermore, our findings highlight differential effects of the various deformation types, which suggest that patterns of covariation between modified vaults and their associated basicrania are more complex than previously assumed, thereby stressing the degree of plasticity in human craniofacial growth.

Artificial deformation versus normal variation: re-examination of artificially deformed crania in ancient Korean populations

Artificial deformation versus normal variation: re-examination of artificially deformed crania in ancient Korean populations

Multitemporal Volume Registration for the Analysis of Rheumatoid Arthritis Evolution in the Wrist.

This paper describes a method based on an automatic segmentation process to coregister carpal bones of the same patient imaged at different time points. A rigid registration was chosen to avoid artificial bone deformations and to allow finding eventual differences in the bone shape due to erosion, disease regression, or other eventual pathological signs. The actual registration step is performed on the basis of principal inertial axes of each carpal bone volume, as estimated from the inertia matrix. In contrast to already published approaches, the proposed method suggests splitting the 3D rotation into successive rotations about one axis at a time (the so-called basic or elemental rotations). In such a way, singularity and ambiguity drawbacks affecting other classical methods, for instance, the Euler angles method, are addressed. The proposed method was quantitatively evaluated using a set of real magnetic resonance imaging (MRI) sequences acquired at two different times from healthy wrists and by choosing a direct volumetric comparison as a cost function. Both the segmentation and registration steps are not based on a priori models, and they are therefore able to obtain good results even in pathological cases, as proven by the visual evaluation of actual pathological cases.

Zwischen Hunnen- und Gepidenzeit. Frauengräber aus dem 5. Jahrhundert im Karpatenbecken

The aim of this study is to investigate the transition between Hunnic and Gepidic period on the basis of female burials in the Middle Danube Region. The analysis of burial practices, female dress accessories and artificial skull deformation prove that there was a continuous cultural transformation during the 5th century, not a radical change. The power structure changed in the middle of the century but it didn’t cause the disappearance of the phenomena which formed from the beginning of the century. The new female representation that emerged after the end of Roman rule in the Carpathian basin can be widely observed from a geographical as well as from a social point of view. The early graves of the Gepidic cemeteries (Reihengräberfelder) fit perfectly in the general archaeological features of the 5th century.

Modern Hybrid Structures for Buildings and Constructions

Objectives: The study considers the areas of improvement of engineering structures and formulates the principles for developing hybrid structures combining the elements with different properties in one constructive system. Methods: The common feature of all approaches that have been described in this study is that the elements included in the hybrid (combined) structure possess different properties. This study provides the detailed analysis of the strut frame hybrid systems with artificial stress control. Findings: The principle of creating hybrid structures implies the efficient combination of different elements in one system that results in lower specific weight of the structure, in simpler production processes, in lower costs of the objects and in higher durability of the structures. The authors suggested and investigated principally new constructive forms of flat and spatial light hybrid (combined) strut frame type systems and the methods of their manufacturing. Technical solutions have been protected by the industrial patents. The stress-deformed conditions of the cross shaped spatial strut systems have been investigated. The rational parameters of the structures have been identified that ensure maximum effect obtained due to the metal consumption decrease. The study investigates the properties of the constructive nonlinearity of the strut frame systems under the conditions of vibrations. New active shapes of the tie bars of the strut frame beams have been found. Application of these new shapes of the tie bars makes it possible to improve the strength of the system by 5…23 %. Applications/Improvements: The combined method of prestressing the strut system applying different techniques of artificial stress and deformation control has been proposed. Application areas for the pre-stressing of this type have been identified. Keywords: Active Shapes of Tie Bars, Combined Pre-Stressing, Hybrid Structures Combined Structures, Pre-stressing, Strut Frame Systems, Spatial Crosswise Strut Systems

A novel learning-based dissimilarity metric for rigid and non-rigid medical image registration by using Bhattacharyya Distances

Image registration is one of the major technologies of the medical image processing and analysis. According to the nature of the transformation, image registration can be categorized into two main classes: Rigid Registration and Non-rigid Registration. In this paper, a novel learning-based dissimilarity metric and its approximation are proposed and respectively adopted to the rigid and non-rigid registration of medical images. This novel metric utilizes Bhattacharyya Distances to measure the dissimilarity of the testing image pairs by incorporating the expected intensity distributions which is learnt from the registered training image pairs. In order to test the robustness and accuracy of the proposed metric in the multi-modal rigid registration, one thousand eight hundred randomized CT–T1 registrations were performed and evaluated by the Retrospective Image Registration Evaluation (RIRE) project. For the non-rigid registration, the approximation of the proposed dissimilarity metric is adopted with the Markov Random Field (MRF) modeled non-rigid registration approach. Non-rigid registration experiments of 2D synthetic images with artificial deformation fields and 3D images from the Simulated Brain Database were performed and evaluated respectively in this paper. The experimental results of both rigid and non-rigid medical image registrations demonstrated that the proposed dissimilarity metric outperforms the state-of-the-art approach (Mutual Information) and the close related approach (Kullback–Leibler Distances).

Use of regularized principal component analysis to model anatomical changes during head and neck radiation therapy for treatment adaptation and response assessment.

To develop standard (SPCA) and regularized (RPCA) principal component analysis models of anatomical changes from daily cone beam CTs (CBCTs) of head and neck (H&N) patients and assess their potential use in adaptive radiation therapy, and for extracting quantitative information for treatment response assessment. Planning CT images of ten H&N patients were artificially deformed to create "digital phantom" images, which modeled systematic anatomical changes during radiation therapy. Artificial deformations closely mirrored patients' actual deformations and were interpolated to generate 35 synthetic CBCTs, representing evolving anatomy over 35 fractions. Deformation vector fields (DVFs) were acquired between pCT and synthetic CBCTs (i.e., digital phantoms) and between pCT and clinical CBCTs. Patient-specific SPCA and RPCA models were built from these synthetic and clinical DVF sets. EigenDVFs (EDVFs) having the largest eigenvalues were hypothesized to capture the major anatomical deformations during treatment. Principal component analysis (PCA) models achieve variable results, depending on the size and location of anatomical change. Random changes prevent or degrade PCA's ability to detect underlying systematic change. RPCA is able to detect smaller systematic changes against the background of random fraction-to-fraction changes and is therefore more successful than SPCA at capturing systematic changes early in treatment. SPCA models were less successful at modeling systematic changes in clinical patient images, which contain a wider range of random motion than synthetic CBCTs, while the regularized approach was able to extract major modes of motion. Leading EDVFs from the both PCA approaches have the potential to capture systematic anatomical change during H&N radiotherapy when systematic changes are large enough with respect to random fraction-to-fraction changes. In all cases the RPCA approach appears to be more reliable at capturing systematic changes, enabling dosimetric consequences to be projected once trends are established early in a treatment course, or based on population models.

SU-F-P-54: Guidelines to Check Image Registration QA of a Clinical Deformation Registration Software: A Single Institution Preliminary Study

Purpose: The objective of this study is to verify and analyze the accuracy of a clinical deformable image registration (DIR) software. Methods: To test clinical DIR software qualitatively and quantitatively, we focused on lung radiotherapy and analyzed a single (Lung) patient CT scan. Artificial anatomical changes were applied to account for daily variations during the course of treatment including the planning target volume (PTV) and organs at risk (OAR). The primary CT (pCT) and the structure set (pST) was deformed with commercial tool (ImSimQA-Oncology Systems Limited) and after artificial deformation (dCT and dST) sent to another commercial tool (VelocityAI-Varian Medical Systems). In Velocity, the deformed CT and structures (dCT and dST) were inversely deformed back to original primary CT (dbpCT and dbpST). We compared the dbpST and pST structure sets using similarity metrics. Furthermore, a binary deformation field vector (BDF) was created and sent to ImSimQA software for comparison with known “ground truth” deformation vector fields (DVF). Results: An image similarity comparison was made by using “ground truth” DVF and “deformed output” BDF with an output of normalized “cross correlation (CC)” and “mutual information (MI)” in ImSimQA software. Results for the lung case were MI=0.66 and CC=0.99. The artificial structure deformation in both pST and dbpST was analyzed using DICE coefficient, mean distance to conformity (MDC) and deformation field error volume histogram (DFEVH) by comparing them before and after inverse deformation. We have noticed inadequate structure match for CTV, ITV and PTV due to close proximity of heart and overall affected by lung expansion. Conclusion: We have seen similarity between pCT and dbpCT but not so well between pST and dbpST, because of inadequate structure deformation in clinical DIR system. This system based quality assurance test will prepare us for adopting the guidelines of upcoming AAPM task group 132 protocol.

Artificial Deformation of Skulls from Bronze Age and Iron Age Armenia

Cultural practices resulting in lasting modifications of the body can be a productive focus of investigation. Artificial cranial modification involves the alteration of cranial vault shape by cultural means, and is performed during infancy or early childhood while the cranial bones remain malleable. Our results indicate that tumpline deformation and cradle deformation should be added to the suite of cranial deformations that were detected in Armenia. It has been determined that the occipital modification is most likely unintentional. Post-coronal depression also appears to be unintentional. Cradle deformation is heavily influenced by infant sleep position, and constant supine positioning is a frequent cause of deformation during infancy. In the Armenian burials 32 skulls showing signs of cradle deformation are identified. Post-coronal depression, positioned on both parietals and slightly posterior to the coronal suture, was detected on 44 of the skulls. The deformation was a correlate of economic activities of the population and was an inadvertent consequence of carrying loads with a band across the parietal bones. In 12 cases a combination of the two types of deformation (tumpline and cradle), is observed. The only modification that has been classified as intentional is one case of parieto-temporal modification. Key words: Armenia, Bronze Age, Iron Age, post-coronal depression, cradle deformation, parieto-temporal modification

Development of Landslide Deformation Monitoring and Analysis System: A Proof of Concept Study

This study introduces a novel landslide monitoring and analysis system, LANSDEMAS. LANSDEMAS is a kinematic deformation analysis model, developed using Kalman filtering procedures and implemented on MATLAB. This study describes the first deformation monitoring and analysis experiment conducted to validate the performance of LANSDEMAS. The experiment was conducted in the 3-D Measurement Laboratory, Department of Geomatic Engineering, Universiti Teknologi Malaysia using Leica TCA2003 Robotic Total Station. In the simulated deformation monitoring experiment, different magnitudes of millimeter-level artificial deformations were applied to four monitored points. The results of the computed movement parameters show that LANSDEMAS accurately detected the introduced deformations and has demonstrated the potential to meet the requirements for landslide deformation monitoring and analysis.

Physical Constraint Finite Element Model for Medical Image Registration.

Due to being derived from linear assumption, most elastic body based non-rigid image registration algorithms are facing challenges for soft tissues with complex nonlinear behavior and with large deformations. To take into account the geometric nonlinearity of soft tissues, we propose a registration algorithm on the basis of Newtonian differential equation. The material behavior of soft tissues is modeled as St. Venant-Kirchhoff elasticity, and the nonlinearity of the continuum represents the quadratic term of the deformation gradient under the Green- St.Venant strain. In our algorithm, the elastic force is formulated as the derivative of the deformation energy with respect to the nodal displacement vectors of the finite element; the external force is determined by the registration similarity gradient flow which drives the floating image deforming to the equilibrium condition. We compared our approach to three other models: 1) the conventional linear elastic finite element model (FEM); 2) the dynamic elastic FEM; 3) the robust block matching (RBM) method. The registration accuracy was measured using three similarities: MSD (Mean Square Difference), NC (Normalized Correlation) and NMI (Normalized Mutual Information), and was also measured using the mean and max distance between the ground seeds and corresponding ones after registration. We validated our method on 60 image pairs including 30 medical image pairs with artificial deformation and 30 clinical image pairs for both the chest chemotherapy treatment in different periods and brain MRI normalization. Our method achieved a distance error of 0.320±0.138 mm in x direction and 0.326±0.111 mm in y direction, MSD of 41.96±13.74, NC of 0.9958±0.0019, NMI of 1.2962±0.0114 for images with large artificial deformations; and average NC of 0.9622±0.008 and NMI of 1.2764±0.0089 for the real clinical cases. Student’s t-test demonstrated that our model statistically outperformed the other methods in comparison (p-values <0.05).

Fully automatic and robust 3D registration of serial-section microscopic images.

Robust and fully automatic 3D registration of serial-section microscopic images is critical for detailed anatomical reconstruction of large biological specimens, such as reconstructions of dense neuronal tissues or 3D histology reconstruction to gain new structural insights. However, robust and fully automatic 3D image registration for biological data is difficult due to complex deformations, unbalanced staining and variations on data appearance. This study presents a fully automatic and robust 3D registration technique for microscopic image reconstruction, and we demonstrate our method on two ssTEM datasets of drosophila brain neural tissues, serial confocal laser scanning microscopic images of a drosophila brain, serial histopathological images of renal cortical tissues and a synthetic test case. The results show that the presented fully automatic method is promising to reassemble continuous volumes and minimize artificial deformations for all data and outperforms four state-of-the-art 3D registration techniques to consistently produce solid 3D reconstructed anatomies with less discontinuities and deformations.

Perceptual transparency from image deformation

Human vision has a remarkable ability to perceive two layers at the same retinal locations, a transparent layer in front of a background surface. Critical image cues to perceptual transparency, studied extensively in the past, are changes in luminance or color that could be caused by light absorptions and reflections by the front layer, but such image changes may not be clearly visible when the front layer consists of a pure transparent material such as water. Our daily experiences with transparent materials of this kind suggest that an alternative potential cue of visual transparency is image deformations of a background pattern caused by light refraction. Although previous studies have indicated that these image deformations, at least static ones, play little role in perceptual transparency, here we show that dynamic image deformations of the background pattern, which could be produced by light refraction on a moving liquid's surface, can produce a vivid impression of a transparent liquid layer without the aid of any other visual cues as to the presence of a transparent layer. Furthermore, a transparent liquid layer perceptually emerges even from a randomly generated dynamic image deformation as long as it is similar to real liquid deformations in its spatiotemporal frequency profile. Our findings indicate that the brain can perceptually infer the presence of "invisible" transparent liquids by analyzing the spatiotemporal structure of dynamic image deformation, for which it uses a relatively simple computation that does not require high-level knowledge about the detailed physics of liquid deformation.

A consistent solution of the re-initialization equation in the conservative level-set method

In this paper, a new re-initialization method for the conservative level-set function is put forward. First, it has been shown that the re-initialization and advection equations of the conservative level-set function are mathematically equivalent to the re-initialization and advection equations of the localized signed distance function. Next, a new discretization for the spatial derivatives of the conservative level-set function has been proposed. This new discretization is consistent with the re-initialization procedure and it guarantees a second-order convergence rate of the interface curvature on gradually refined grids. The new re-initialization method does not introduce artificial deformations to stationary and non-stationary interfaces, even when the number of re-initialization steps is large.

ORTHOSTATIC TORTUOSITIS TRANSFORMATION OF THE NECK’S MAIN ARTERIES

Among 350 surveyed deformations of internal carotid arteries revealed in 38.6% of cases. At pathological deformation observed acceleration of flow speed indicators from 55% to 65% in part of tortuosity, average value of systolic speeds of a blood flow was 166±28.3 cm/s at the left and 174±30.2 cm/s at the right side. In vertical position in 31.6% of cases at pathological deformation observed transfor mation of tortuosity form. deformation corners became blunt, the gradient of flow speed indicators decreased or was absent, in some cases course of internal carotid arteries became rectilinear. Artificial deformations of vertebral arteries course revealed in 79.4% of people, average value of systolic speed of a blood flow was 92±15.3 cm/s at the left and 76±12.5 cm/s at the right side. In vertical position in deformations of the vertebral arteries, which carried to pathological, in 28.8% of cases a form of deformation was transformed to unpathological tortuosity. duplex sonography in vertical position in patients with tortuosity discovered new approaches in diagnostics of pathological deformations and defines indications to operative treatment.

Multimodal image registration with joint structure tensor and local entropy.

Nonrigid registration of multimodal medical images remains a challenge in image-guided interventions. A common approach is to use mutual information (MI), which is robust to the intensity variations across modalities. However, primarily based on intensity distribution, MI does not take into account of underlying spatial and structural information of the images, which might lead to local optimization. To address such a challenge, this paper proposes a two-stage multimodal nonrigid registration scheme with joint structural information and local entropy. In our two-stage multimodal nonrigid registration scheme, both the reference image and floating image are firstly converted to a common space. A unified representation in the common space for the images is constructed by fusing the structure tensor (ST) trace with the local entropy (LE). Through the representation that reflects its geometry uniformly across modalities, the complicated deformation field is estimated using L(1) or L(2) distance. We compared our approach to four other methods: (1) the method using LE, (2) the method using ST, (3) the method using spatially weighted LE and (4) the conventional MI-based method. Quantitative evaluations on 80 multimodal image pairs of different organs including 50 pairs of MR images with artificial deformations, 20 pairs of medical brain MR images and 10 pairs of breast images showed that our proposed method outperformed the comparison methods. Student's t test demonstrated that our method achieved statistically significant improvement on registration accuracy. The two-stage registration with joint ST and LE outperformed the conventional MI-based method for multimodal images. Both the ST and the LE contributed to the improved registration accuracy.

Population of Viminacium during the Migration Period: Segment without artificially deformed skulls

In the 1980s, at the site of Viminacium - Vise Grobalja, 31 artificially deformed skulls were discovered at the necropolis ascribed to the Gepids. These skulls attracted much attention from anthropologists as they represent the largest series of artificially deformed skulls in this part of Europe. Another 63 skulls, showing no traces of artificial deformation have, thus far, been disregarded, hence they will now be published in more detail and those best preserved, illustrated in this paper. In 2006, the published archaeological analysis confirmed that this site is, in fact, a case of two necropolises from the Migration Period, which were, however, spatially and chronologically linked. They were named as Viminacium II, specifically Vise Grobalja 1 and Vise Grobalja 2. The older necropolis (1) contained 36 skeletons, and the younger (2), 58 skeletons. This paper includes another two Viminacium necropolises from the Migration Period - the necropolis of Burdelj (i.e. Viminacium I) with 66 graves and the necropolis of Lanci (i.e. Viminacium III) with 15 graves. Simply stated, the anthropological characteristics of the skeletons from these four necropolises of Viminacium from the Migration Period - Burdelj, Vise Grobalja 1, Vise Grobalja 2 and Lanci, excluding the previously published artificially deformed skulls, demonstrate a low degree of heterogeneity.

Исследование процесса старения холоднокатанного и горячеоцинкованного проката

In this paper, a study was conducted of the aging process of cold and hot dip galvanized sheet to obtain data on the timing guarantees the mechanical properties of rolled metal production of OJSC Magnitogorsk Iron and Steel Works (MMK) during storage and processing of consumers. Considered two basic types of aging, namely natural and artificial (deformation, thermal and thermodeformation). For the experiment was selected following assortment: hot dip galvanized sheet steel grades DX52D and 08ps; cold-rolled sheet steel production 08U of rolling mill № 5; cold-rolled sheet of steel grades 08U and 10ps production of rolling mill № 11 "Magnitogorsk Iron and Steel Works." The experimental part was carried out a tensile test to determine the change in mechanical properties as a result of the test assortment different types of aging. The experimental results were constructed depending that show changes in the mechanical properties and propensity to aging test sheet. It has been established that the supplier can store cold-rolled and hot dip galvanized sheet steel DX52D, 08U, 10ps in the warehouse for 3-6 months with guaranteed mechanical properties. Hot dip galvanized steel grade 08ps begins to age in 10 days. In turn, straightening, unwinding rolls, as well as other actions with a sheet accompanied by heating and plastic deformation leads to a change in the mechanical properties of steel. It is necessary to consider both suppliers and consumers of products.