Multi-Surface Simplex Spine Segmentation for Spine Surgery Simulation and Planning

This research proposes to develop a knowledge-based multi-surface simplex deformable model for segmentation of healthy as well as pathological lumbar spine data. It aims to provide a more accurate and robust segmentation scheme for identification of intervertebral disc pathologies to assist with spine surgery planning. A robust technique that combines multi-surface and shape statistics-aware variants of the deformable simplex model is presented. Statistical shape variation within the dataset has been captured by application of principal component analysis and incorporated during the segmentation process to refine results. In the case where shape statistics hinder detection of the pathological region, user-assistance is allowed to disable the prior shape influence during deformation. Results have been validated against user-assisted expert segmentation

Deformable Multisurface Segmentation of the Spine for Orthopedic Surgery Planning and Simulation

Purpose: We describe a shape-aware multisurface simplex deformable model for the segmentation of healthy as well as pathological lumbar spine in medical image data. Approach: This model provides an accurate and robust segmentation scheme for the identification of intervertebral disc pathologies to enable the minimally supervised planning and patient-specific simulation of spine surgery, in a manner that combines multisurface and shape statistics-based variants of the deformable simplex model. Statistical shape variation within the dataset has been captured by application of principal component analysis and incorporated during the segmentation process to refine results. In the case where shape statistics hinder detection of the pathological region, user assistance is allowed to disable the prior shape influence during deformation. Results: Results demonstrate validation against user-assisted expert segmentation, showing excellent boundary agreement and prevention of spatial overlap between neighboring surfaces. This section also plots the characteristics of the statistical shape model, such as compactness, generalizability and specificity, as a function of the number of modes used to represent the family of shapes. Final results demonstrate a proof-of-concept deformation application based on the open-source surgery simulation Simulation Open Framework Architecture toolkit. Conclusions: To summarize, we present a deformable multisurface model that embeds a shape statistics force, with applications to surgery planning and simulation

The Mosasaur Prognathodon (Reptilia, Mosasauridae) from the Upper Cretaceous of Belgium

The osteology of the mosasaurs Prognathodon solvayi and P. giganteus is extensively described for the first time. P. solvayi is known from the holotype IRSNB R33, a complete skull and partially preserved postcranial remains as well as from fragmentary material from specimens IRSNB R107 and IRSNB R108. P. giganteus is based wholly on the fragmentary cranial and postcranial remains of the type specimen IRSNB R106. Both species are compared with the North American taxa P. overtoni (KU 950, the holotype), P.? overloni (SDSM 3393), P. rapax (AMNH 1490),? Prognathodon (FMNH PR 165) and "Prognathodon" crassartus (AMNH 1562). P. sotvayi and P. giganteus are less similar to each other than are P. giganteus and SDSM 3393, referred to P. overtoni by RUSSELL (1967), especially with regard to overall shape and size. Because of the very fragmentary holotype material of P. overtoni comparisons with it are restricted. Characters critical in the classification of Prognathodon (such as dentition, zygosphenes, zygantra and haemal arches) are re-assessed. Re-evaluation of these characters induces changes in the generic assignments of the taxa within the Plioplatecarpinae. "Prognathodon" crassartus is reassigned to Plioplatecarpus. The status of FMNH PR 165, referred to Prognathodon by RUSSELL (1970) is questioned on the basis of conflicting diagnostic characters; it is a large plioptatecarpine mosasaur probably more closely related to Selmasaurus or Plioplatecarpus. Dollosaurus IAKOVLEV, 1901 is synonymised wiih Prognathodon. The ecology of Prognathodon and certain other mosasaurs of Belgium is discussed and comparisons are made with other aquatic vertebrates

Shape recognition of the spine with snakes and its application for diagnosing osteoporosis

骨粗鬆症の診断では骨密度（BMD）を一つの指標としているが，BMD値と疾病の程度とが必ずしも相関しないことがあり，われわれは第三腰椎のCT画像から得られる情報を用いてさらに正確な診断を行う方法を検討してきた.本研究では第三腰椎X線CT画像を用いて，種々の領域の輪郭抽出を行い，そこから算出されたパラメータの有効性を調べた．ここで椎孔および骨皮質内部（椎体内海綿骨部）の輪郭抽出にはsnakesを適用し，輪郭抽出のための新たなエネルギー関数を導入し，高い精度での自動輪郭抽出に成功した．また，得られたパラメータの臨床的有用性についても検討を行った．Bone mineral density (BMD) is an index in the diagnosis of osteoporosis. But the BMD value sometimes does not correlate to the prognosis of this disease. We have studied methods for diagnosing the osteoporosis by means of information obtained from a CT image of the third lumbar vertebra. In this study we extracted outlines of various areas automatically from the CT image and calculated three types of parameters useful to diagnose the osteoporosis. The snake algorithm was applied to extract contour of the foramen and the trabecular bone region with a newly developed energy function, and it succeeded in the automatic outline extraction with high accuracy. Moreover, clinical usefulness of obtained parameters was examined with a statistical analysis

X-ray Image Segmentation and An Internet-based Tool for Medical Validation

Segmentation of vertebrae in X-ray images is a difficult task that requires an effective segmentation procedure. Noise, poor image contrast, occlusions and shape variability are some of the challenges in many of the spine X-ray images archived at the U.S. National Library of Medicine (NLM). In this thesis, we propose a curvature-based corner matching approach, which exploits the posterior corners of the vertebra to estimate the location and orientation of the vertebrae. The key advantage of the proposed approach is execution time, roughly about one-fifth of the previous approach that uses the generalized Hough transform when tested on a sizeable set of cervical spine images. This thesis also presents the first ever effort to develop a prototype internet-based medical image segmentation and pathology validation tool, which enables radiologists to validate computer generated image segmentations, modify existing or create new segmentation in addition to identifying pertinent pathology data

No. 19, Fernvale (40WM51), A Late Archaic Occupation Along the South Harpeth River in Williamson County, Tennessee

https://digitalcommons.memphis.edu/govpubs-tn-dept-environment-conservation-archaeology-research-series/1018/thumbnail.jp

A Pliocene-Pleistocene continental biota from Venezuela

The Pliocene-Pleistocene transition in the Neotropics is poorly understood despite the major climatic changes that occurred at the onset of the Quaternary. The San Gregorio Formation, the younger unit of the Urumaco Sequence, preserves a fauna that documents this critical transition. We report stingrays, freshwater bony fishes, amphibians, crocodiles, lizards, snakes, aquatic and terrestrial turtles, and mammals. A total of 49 taxa are reported from the Vergel Member (late Pliocene) and nine taxa from the Cocuiza Member (Early Pleistocene), with 28 and 18 taxa reported for the first time in the Urumaco sequence and Venezuela, respectively. Our findings include the first fossil record of the freshwater fishes Megaleporinus, Schizodon, Amblydoras, Scorpiodoras, and the pipesnake Anilius scytale, all from Pliocene strata. The late Pliocene and Early Pleistocene ages proposed here for the Vergel and Cocuiza members, respectively, are supported by their stratigraphic position, palynology, nannoplankton, and 86 Sr/ 88 Sr dating. Mammals from the Vergel Member are associated with the first major pulse of the Great American Biotic Interchange. In contrast to the dry conditions prevailing today, the San Gregorio Formation documents mixed open grassland/forest areas surrounding permanent freshwater systems, following the isolation of the northern South American basin from western Amazonia. These findings support the hypothesis that range contraction of many taxa to their current distribution in northern South America occurred rapidly during at least the last 1.5 million years

Statistical anatomical modelling for efficient and personalised spine biomechanical models

Personalised medicine is redefining the present and future of healthcare by increasing treatment efficacy and predicting diseases before they actually manifest. This innovative approach takes into consideration patient’s unique genes, environment, and lifestyle. An essential component is physics-based simulations, which allows the outcome of a treatment or a disease to be replicated and visualised using a computer. The main requirement to perform this type of simulation is to build patient-specific models. These models require the extraction of realistic object geometries from images, as well as the detection of diseases or deformities to improve the estimation of the material properties of the studied object. The aim of this thesis was the design of a general framework for creating patient- specific models for biomechanical simulations using a framework based on statistical shape models. The proposed methodology was tested on the construction of spine models, including vertebrae and intervertebral discs (IVD). The proposed framework is divided into three well-defined components: The paramount and first step is the extraction of the organ or anatomical structure from medical images. In the case of the spine, IVDs and vertebrae were extracted from Magnetic Resonance images (MRI) and Computed Tomography (CT), respectively. The second step is the classification of objects according to different factors, for instance, bones by its type and grade of fracture or IVDs by its degree of degeneration. This process is essential to properly model material properties, which depends on the possible pathologies of the tissue. The last component of the framework is the creation of the patient-specific model itself by combining the information from previous steps. The behaviour of the developed algorithms was tested using different datasets of spine images from both computed tomography (CT) and Magnetic resonance (MR) images from different institutions, type of population and image resolution

Correlation between vertebral Hox code and vertebral morphology in archosaurs

The evolution of the vertebral column is marked by profound morphological changes that have a strong impact on organismal biology. The vital functions of the axial skeleton range from protecting the neural structures through sustaining the body posture to physiological aspects such as breathing. Archosaurs (crocodiles, birds and dinosaurs), as a group, display a striking variety of body plans and vertebral morphologies. This dissertation aims to contribute to the understanding of the pattern and the genetic basis for the evolution of the vertebral column in archosaurs. The transdisciplinary project comprises five chapters. Framed by a general introduction (chapter 1) and the conclusion (chapter 5), the second chapter considers, from a morphofunctional point of view, the question of (1) why differences in the vertebral column evolved. The present thesis revealed a strong link between the digitally simulated flexion pattern of the presacral vertebral column and the axial movements of modern archosaurs during related activities such as feeding and locomotion: this correlation allowed the inference of the feeding range and locomotor options in the extinct archosaur Plateosaurus. This long-necked dinosaur was primarily adapted as mid-level browser, obtaining food that was at or above the horizontal level of its head. There is currently no evidence to unambiguously interpret the locomotion style of Plateosaurus. The morphofunctional analysis supported both a quadrupedal and a bipedal posture. The third chapter addresses, from a molecular biology point of view, the question (2) of how modern taxa develop their vertebral columns. It provides insights into the genetic basis for the embryonic development of the vertebral column in modern archosaurs, which includes the highly conserved Hox genes. The Hox gene expression pattern was detected in the Nile crocodile (Crocodylus niloticus) via whole-mount in situ hybridisation experiments. Hox paralog genes 4 and 5 are expressed in the cervical region of the crocodile. The anterior expression limit of HoxC-6 marks the cervicothoracic transition. The expression of Hox paralog genes 7 and 8 is restricted to the dorsal series. The same Hox genes are expressed along the anteroposterior body axis of crocodiles, chickens and mice, but the pattern of expression is different. The comparative analysis revealed two general processes that are accompanied by evolutionary differences in the axial skeleton: 1) expansion and condensation as well as 2) a shift of genetic activity corresponding to different vertebral counts. The strong association between the anterior limits of the expression of specific Hox genes and the borders between morphological regions of the vertebral axis in a variety of vertebrate species stimulated the work presented in the fourth chapter. It considers the question (3) of whether we can infer that the development of the vertebral column took place in extinct animals. The direct correlation between vertebral Hox code and quantifiable vertebral morphology shows that the genetic code is deducible from vertebral morphology in modern crocodiles, chickens and mice. Applying these findings to the fossil relative Plateosaurus revealed that the hypothetical Hox code for the dinosaur would be generally similar to the crocodilian Hox gene expression pattern, but with the variation that the anterior region is expanded, as in birds. The integrative analysis (morphology, genes and fossils) of the vertebrae greatly enhanced our knowledge of evolutionary processes and provided valuable information about the possible reasons, genetic basis and pattern for evolutionary changes of the vertebral column in extant and extinct archosaurs.Im Laufe der Evolution hat die Wirbelsäule tiefgreifende morphologische Veränderungen erfahren, die sich signifikant auf die Biologie der Organismen ausgewirkt haben. Die lebenswichtigen Funktionen des Axialskeletts reichen vom Schutz der neuralen Strukturen, über die Stützung des Körpers, bis hin zu physiologischen Aufgaben wie beispielsweise der Atmung. Archosauria (Krokodile, Vögel und Dinosaurier) zeigen eine bemerkenswerte Vielfalt an Körperbauplänen und Wirbelmorphologien. Das Ziel der Dissertation besteht darin, einen entscheidenden Beitrag zum Verständnis der Muster und der genetischen Basis für die Evolution der Wirbelsäule bei Archosauriern zu liefern. Das interdisziplinäre Projekt umfasst fünf Kapitel. Neben einer allgemeinen Einleitung (Kapitel 1) und den Schlussbemerkungen (Kapitel 5), widmet sich das zweite Kapitel aus morphofunktionaler Sicht der Frage (1) warum sich Unterschiede in der Wirbelsäule während der Evolution entwickelt haben. Die vorliegende Arbeit zeigt einen engen Zusammenhang zwischen dem digital simulierten Flexionsmuster der präsakralen Wirbelsäule und den axialen Bewegungen moderner Archosaurier während relevanter Aktivitäten wie beispielsweise Nahrungsaufnahme und Lokomotion. Diese Korrelation ermöglichte es, auf die Nahrungsreichweite sowie die Fortbewegungsmöglichkeiten des ausgestorbenen Archosauriers Plateosaurus rückzuschließen. Dieser langhalsige Dinosaurier war primär als Laubäser auf mittlerem Niveau angepasst, der Nahrung auf oder oberhalb seiner horizontalen Kopfhöhe aufgenommen hat. Es konnte kein eindeutiger Hinweis auf die Fortbewegungsweise von Plateosaurus erbracht werden. Die Ergebnisse der morphofunktionalen Analyse unterstützen sowohl eine quadrupedale als auch eine bipedale Haltung. Das dritte Kapitel behandelt aus molekularbiologischer Sicht die Frage (2) wie moderne Arten ihre Wirbelsäule entwickeln. Es liefert Einsichten in die genetische Basis der embryonalen Entwicklung der Wirbelsäule von modernen Archosauriern; die hoch konservativen Hox Gene. Das Expressionsmuster der Hox Gene wurde beim Nilkrokodil (Crocodylus niloticus) mittels whole-mount in situ Hybridisierungsexperimenten nachgewiesen. Die Hox Gene der paralogen Gruppe 4 und 5 werden in der Halswirbelsäule des Krokodils exprimiert. Die anteriore Expressionsgrenze von HoxC-6 markiert den Übergang von Hals- zu Brustwirbelsäule. Die Hox Gene der paralogen Gruppe 7 und 8 sind auf die Brust- und Lendenwirbelsäule begrenzt. Die gleichen Hox Gene werden entlang der anteroposterioren Körperachse des Krokodils, des Huhns und der Maus exprimiert. Das Muster der Expression ist jedoch unterschiedlich. Die vergleichende Analyse hat zwei generelle Prozesse aufgezeigt, die mit den evolutionären Veränderungen des Axialskeletts in Zusammenhang stehen: 1) die Expansion und Kondensation sowie 2) eine Verschiebung der genetischen Aktivität entsprechend der unterschiedlichen Wirbelanzahl. Der enge Zusammenhang zwischen den anterioren Expressionsgrenzen von spezifischen Hox Genen und den Grenzen zwischen morphologischen Regionen der Wirbelsäule bei einer Vielzahl von Wirbeltierarten regte die Arbeit an, die im vierten Kapitel vorgestellt wird. Es widmet sich der Frage (3) ob man auf die Entwicklung der Wirbelsäule von ausgestorbenen Tieren rückschließen kann. Die direkte Korrelation zwischen dem Hox Code und der quantifizierbaren Wirbelmorphologie zeigt, dass der jeweilige genetische Code von der Wirbelform des modernen Krokodils, Huhns und der Maus ableitbar ist. Diese Ergebnisse wurden auf den fossilen Verwandten Plateosaurus angewendet und lieferten den hypothetischen Hox Code für den Dinosaurier. Er wäre generell ähnlich zum Hox Gen-Expressionsmuster des Krokodils mit der Variation, dass die anteriore Region wie beim Vogel expandiert wäre. Die integrative Analyse (Morphologie, Gene und Fossilien) der Wirbel hat unsere Kenntnis über evolutionäre Prozesse grundlegend erweitert. Sie hat wertvolle Informationen über die möglichen Ursachen, die genetische Basis sowie das Muster der evolutionären Veränderungen der Wirbelsäule heutiger und ausgestorbener Archosaurier geliefert

A faunal analysis of the Jackson Site (diMe-17) in southwestern Manitoba

The Jackson site (DiMe-17) is a Late Precontact site located in the Lauder Sandhills of southwestern Manitoba. The majority of the site consists of a Vickers Focus bison kill and associated processing/refuse areas radiocarbon dated to 290±50, 300±70, and 410±60 BP. At the southwestern corner of the site, a small amount of Blackduck pottery was recovered below the Vickers Focus occupation. Excavations occurred at the site between 1994 and 1997 and were completed by university archaeological field school students, paid crew members, and one volunteer. The site was excavated in an attempt to better understand the Vickers Focus presence in the Lauder Sandhills and to provide archaeological field school students with an opportunity to gain first hand knowledge of field excavation techniques. A total of 194, 198 bone specimens were analyzed from the Vickers Focus occupation at the Jackson site. Element and species distribution patterns verified proposed activity areas, while an examination of bison mandible eruption and wear patterns in conjunction with foetal bison remains corroborate that the site was occupied during the winter months. The fragmented nature of the assemblage is a result of human butchery and subsequent processing of elements for marrow and grease. Non-cultural processes such as carnivore modification, weathering, rootlet etching, and trampling left visible traces on the assemblage but did not cause density-mediated destruction. A comparison of the subsistence strategies employed by the Jackson and Sanderson site inhabitants did not provide sufficient information to confirm proposed contact between Vickers Focus and Mortlach groups. The Sanderson site is a multiple Mortlach occupation located on the Souris River in southeastern Saskatchewan. Inhabitants of both sites were reliant on bison, and both employed a smash and strip method of bison butchery. Intensive bison utilization was evident at both sites but the Jackson site inhabitants may have been under greater nutritional stress. The greatest difference between the two groups was visible in the method of meat storage. The Mortlach inhabitants at the Sanderson site used frozen meat caches while no such evidence for this exists at the Jackson site