61 research outputs found
Automated Segmentation of Recuts Abdominis Muscle Using Shape Model in X-Ray CT Images
Abstract-Our purpose in this study is to segment the rectus abdominis muscle region in X-ray CT images, and we propose a novel recognition method based on the shape model. In this method, three steps are included in the segmentation process. The first is to generate a shape model for the rectus abdominis muscle. The second is to recognize anatomical feature points corresponding to the origin and insertion of the muscle, and the third is to segment the rectus abdominis muscles based on the shape model. We generated the shape model from 20 CT cases and tested the model to recognize the muscle in 20 other CT cases. The average values for the Jaccard similarity coefficient (JSC) and true segmentation coefficient (TSC) were 0.841 and 0.863, respectively. The results suggest the validity of the model-based segmentation for the rectus abdominis muscle
Adaptive kernel estimation for enhanced filtering and pattern classification of magnetic resonance imaging: novel techniques for evaluating the biomechanics and pathologic conditions of the lumbar spine
This dissertation investigates the contribution the lumbar spine musculature has on etiological and pathogenic characteristics of low back pain and lumbar spondylosis. This endeavor necessarily required a two-step process: 1) design of an accurate post-processing method for extracting relevant information via magnetic resonance images and 2) determine pathological trends by elucidating high-dimensional datasets through multivariate pattern classification. The lumbar musculature was initially evaluated by post-processing and segmentation of magnetic resonance (MR) images of the lumbar spine, which characteristically suffer from nonlinear corruption of the signal intensity. This so called intensity inhomogeneity degrades the efficacy of traditional intensity-based segmentation algorithms. Proposed in this dissertation is a solution for filtering individual MR images by extracting a map of the underlying intensity inhomogeneity to adaptively generate local estimates of the kernel’s optimal bandwidth. The adaptive kernel is implemented and tested within the structure of the non-local means filter, but also generalized and extended to the Gaussian and anisotropic diffusion filters. Testing of the proposed filters showed that the adaptive kernel significantly outperformed their non-adaptive counterparts. A variety of performance metrics were utilized to measure either fine feature preservation or accuracy of post-processed segmentation. Based on these metrics the adaptive filters proposed in this dissertation significantly outperformed the non-adaptive versions. Using the proposed filter, the MR data was semi-automatically segmented to delineate between adipose and lean muscle tissues. Two important findings were reached utilizing this data. First, a clear distinction between the musculature of males and females was established that provided 100% accuracy in being able to predict gender. Second, degenerative lumbar spines were accurately predicted at a rate of up to 92% accuracy. These results solidify prior assumptions made regarding sexual dimorphic anatomy and the pathogenic nature of degenerative spine disease
Cultivate Quantitative Magnetic Resonance Imaging Methods to Measure Markers of Health and Translate to Large Scale Cohort Studies
Magnetic Resonance Imaging (MRI) is an indispensable tool in healthcare and research, with a growing demand for its services. The appeal of MRI stems from its non-ionizing radiation nature, ability to generate high-resolution images of internal organs and structures without invasive procedures, and capacity to provide quantitative assessments of tissue properties such as ectopic fat, body composition, and organ volume. All without long term side effects. Nine published papers are submitted which show the cultivation of quantitative measures of ectopic fat within the liver and pancreas using MRI, and the process of validating whole-body composition and organ volume measurements. All these techniques have been translated into large-scale studies to improve health measurements in large population cohorts. Translating this work into large-scale studies, including the use of artificial intelligence, is included. Additionally, an evaluation accompanies these published studies, appraising the evolution of these quantitative MRI techniques from the conception to their application in large cohort studies. Finally, this appraisal provides a summary of future work on crowdsourcing of ground truth training data to facilitate its use in wider applications of artificial intelligence.In conclusion, this body of work presents a portfolio of evidence to fulfil the requirements of a PhD by published works at the University of Salford
Evaluating footwear “in the wild”: Examining wrap and lace trail shoe closures during trail running
Trail running participation has grown over the last two decades. As a result, there have been an increasing number of studies examining the sport. Despite these increases, there is a lack of understanding regarding the effects of footwear on trail running biomechanics in ecologically valid conditions. The purpose of our study was to evaluate how a Wrap vs. Lace closure (on the same shoe) impacts running biomechanics on a trail. Thirty subjects ran a trail loop in each shoe while wearing a global positioning system (GPS) watch, heart rate monitor, inertial measurement units (IMUs), and plantar pressure insoles. The Wrap closure reduced peak foot eversion velocity (measured via IMU), which has been associated with fit. The Wrap closure also increased heel contact area, which is also associated with fit. This increase may be associated with the subjective preference for the Wrap. Lastly, runners had a small but significant increase in running speed in the Wrap shoe with no differences in heart rate nor subjective exertion. In total, the Wrap closure fit better than the Lace closure on a variety of terrain. This study demonstrates the feasibility of detecting meaningful biomechanical differences between footwear features in the wild using statistical tools and study design. Evaluating footwear in ecologically valid environments often creates additional variance in the data. This variance should not be treated as noise; instead, it is critical to capture this additional variance and challenges of ecologically valid terrain if we hope to use biomechanics to impact the development of new products
Examining the Neuromuscular and Mechanical Characteristics of the Abdominal Musculature and Connective Tissues: Implications for Stiffening the Lumbar Spine
Research has uncovered an essential role of proper abdominal muscle function in ensuring the health and integrity of the lumbar spine. The anatomical arrangement of the abdominal musculature (rectus abdominis, external oblique, internal oblique, transverse abdominis) and intervening connective tissues is unique in the human body. Despite the hypothesized importance and uniqueness of the abdominal muscles, very little research has been directed to understanding their role from a neuro-mechanical standpoint. Thus, this thesis was designed to study the neuro-activation and mechanical characteristics of the abdominal musculature and connective tissues, with a specific focus on torso stiffening mechanisms. Several experiments were performed and unified around this theme. The first study explored the fundamental relationship between EMG muscle activation recordings and the moments generated by the trunk musculature. This study was novel in that investigation of the abdominal musculature was augmented with consideration of antagonist muscle co-activation. The main finding was that the EMG-moment relationships were quite similar in both the abdominal and extensor muscle groups; however, the form of this relationship differed from that often reported in the literature. Specifically, consideration of antagonist muscle moments linearized the EMG-moment relationship of the agonist muscle groups. Once this activation-moment relationship had been established, the next line of questioning explored the association between torso muscle activation, driven through the abdominals, and torso stiffness. Two studies addressed this issue: the first examined the intrinsic resistance of the torso to bending in the flexion, extension, and lateral bend directions, while varying the levels of torso muscle activation; the second examined the response of the trunk to perturbations while varying the levels of torso muscle activation under the presence of limited reflexes. The first of these two studies demonstrated a rise in trunk stiffness as muscle activation increased over the lower 40% of range of motion. At greater ranges of motion in flexion and lateral bend the trunk appeared to become less stiff as the musculature contracted to higher levels. The latter study revealed substantial spinal displacements in response to trunk perturbations, indicating that in the absence of reflex activity, the stiffness produced by muscular contraction may be inadequate to stiffen the torso to prevent damage to spinal tissues. The fourth study was designed to enable in-vivo observation of abdominal muscle and connective tissue deformation using ultrasound imaging. During relatively simple abdominal contractions, the oblique aponeurosis demonstrated surprising deformation patterns that often exhibited the characteristic of a negative Poisson’s ratio. This was hypothesized to be facilitated by the composite laminate arrangement of the abdominal wall, whereby the loose connective tissues separating layers of collagen fibres may allow for separation of adjacent layers, giving the appearance of structural volume expansion. Further, a lateral displacement of the rectus abdominis muscle was noted in a majority of contractions, highlighting the dominance of the laterally oriented forces generated by the oblique muscles. The final study questioned, at a basic level, the nature of the anatomical arrangement of the abdominal muscle-connective tissue network. Examining the contraction of the rat abdominal wall uncovered the transfer of muscularly generated force and stiffness through the connective tissues binding the layered muscles. This suggests a functionality of the abdominal wall as a composite laminate structure, allowing substantial multi-directional stiffness to be generated and transmitted around the torso, thereby enhancing the ability to effectively stabilize the spine
Management of pelvic ring injuries
Jan Lindahl: MANAGEMENT OF PELVIC RING INJURIES
Unstable pelvic ring injuries are relatively rare injuries, but they constitute a major cause of death and disability in high-energy polytrauma patients Massive hemorrhage is the leading cause of potentially preventable death following a blunt pelvic trauma. The overall aim of surgical treatment for unstable pelvic ring injuries is to restore the pelvic anatomy and perform neural decompression, thus allowing normal function with a low rate of complications.
This doctoral thesis was initiated to investigate the outcomes of acute and definitive management strategies for unstable pelvic ring injuries. The first study investigated the radiological and functional results of treating type B and C pelvic injuries with an anterior external fixation frame. The second study focused on identifying factors for early predictions of mortality-related outcome and prognosis in patients with pelvic fracture-related arterial bleeding that were treated with transcatheter angiographic embolization (TAE). The third study investigated the outcomes of type C pelvic fractures treated with standardized reduction and internal fixation methods. The fourth study evaluated outcomes and identified prognostic factors for operatively-treated, H-shaped sacral fractures with spinopelvic dissociation.
Study I showed that an anterior external fixator failed to achieve and properly maintain reduction in 75% of type B open book injuries and in nearly all (95%) type C pelvic ring injuries. Therefore, an external frame is not a suitable method of treatment for the most unstable pelvic ring injuries as a definitive treatment. The current clinical applications of anterior pelvic external fixators comprise the resuscitation phase, initial fracture stabilization phase, and sometimes, in complex injuries (type C), the definitive phase for fixation of the anterior part of the pelvic ring, in conjunction with posterior internal fixation.
Study II of pelvic fracture related arterial bleedings showed that the worst prognosis was related to exsanguinating bleeding from the main trunk of the internal or external iliac artery (large pelvic arteries) or from multiple branches of the internal or external iliac vasculature (high vessel size score). Definitive control of arterial bleeding was achieved with TAE in all patients. In massive hemorrhage with several bleeding arteries uni- or bilaterally, it is reasonable to use non-selective embolization by promptly occluding the main trunk of the internal iliac artery, either uni- or bilaterally.
Study III of operatively treated type C pelvic fractures revealed that, internal fixation of injuries in the posterior and anterior pelvic ring provided excellent or good radiological results in 90% of cases. Additionally, because a reduction with displacement less than or equal to 5 mm was more often associated with a good functional outcome, that should be the goal of operative management. However, the prognosis is also often dependent on associated injuries, particularly a permanent lumbosacral plexus injury. The results favoured internal fixation of all the injured elements of the pelvis for improved stability and a more accurate anatomical result in the entire pelvic ring.
The H-shaped sacral fracture with spinopelvic dissociation is a rare injury pattern. Study IV revealed that lumbopelvic fixation was a reliable treatment method. The study also showed that neurological recovery and clinical outcome were associated with the degree of initial translational displacement of the transverse sacral fracture component. Permanent neurological deficits were more frequent and the clinical outcome was worst in completely displaced transverse sacral fractures. An accurate operative reduction of all sacral fracture components was associated with better neurological recovery and clinical outcome.
We conclude, that with appropriate treatment of unstable pelvic ring injuries, and associated injuries in other organs, it is possible to achieve better survival rates and functional results, and to reduce long-term disability.Jan Lindahl: LANTIORENKAAN MURTUMIEN HOITO (MANAGEMENT OF PELVIC RING INJURIES)
Lantiorenkaan murtumat ovat suhteellisen harvinaisia vammoja käsittäen 1% kaikista sairaalahoitoa vaativista murtumista Suomessa. Epätukevat lantiorenkaan murtumat syntyvät yleensä suuren vammaenergian seurauksena ja niihin liittyy usein muiden kehonosien vammoja. Massiivinen verenvuoto on merkittävin ja usein estettävissä oleva kuolinsyy tylpällä vammamekanismilla syntyneissä lantiorenkaan vammoissa. Mikäli akuuttivaiheen hoito ei ole tehokasta, massiivinen verenvuoto johtaa sydämen ja verenkierron pettämiseen ja potilaan kuolemaan. Tämän väitöskirjatutkimuksen tarkoituksena oli selvittää: 1) ulkoisen tukilaitteen soveltuvuus B- ja C-tyypin lantiorenkaan murtumien lopulliseksi hoitomuodoksi, 2) hengenvaarallisten, runsaasti vuotavien lantionmurtumien alkuvaiheen vuodon tukkimista embolisaation (TAE) avulla ja samalla kartoittaa riskitekijöitä, jotka ennustavat huonoa lopputulosta ja potilaan kuolemaa vaikeimmin vammautuneiden lantionmurtumapotilaiden kohdalla, 3) C-tyypin murtumien kohdalla standardoidun leikkaushoidon ja sisäisen kiinnitysmenetelmän luotettavuutta ja hoidon pitkäaikaistulokset ja 4) ristiluun vaikeimpien ns. H-tyypin murtumien leikkaushoidon luotettavuutta sekä saavutetun asennonkorjauksen, murtumakiinnityksen ja hermorakenteiden vapautuksen pitkäaikaistulokset sekä toipumisennusteeseen vaikuttavat tekijät.
Ensimmäisen osajulkaisun tulokset osoittivat, että lantiorenkaan etuosaan kiinnitettävä ulkoinen kiinnityslaite (externi fiksaatiolaite) ei ollut luotettava, eikä sillä voitu taata asianmukaista murtuman paikalleen asettamista ja hyvää lopputulosta vaikeimmissa B- ja C-tyypin murtumissa.
Toinen osajulkaisu osoitti, että vuotavien lantionmurtumien kohdalla huonoin ennuste liittyi lantiovammoihin, joissa valtimoiden varjoainekuvauksessa (angiografiassa) todettiin lantion päävaltimon (arteria iliaca interna tai externa) repeämä tai useampia samanaikaisia pienempien valtimosuonten repeämiä. Embolisaatio osoittautui luotettavaksi hoitomenetelmäksi ja kaikki valtimoperäiset vuodot pystyttiin tukkimaan. Kriittisessä vuototilanteessa, jossa angiografiassa todetaan useita vuotokohtia lantion valtimoissa, tulee embolisaatio suorittaa ei-selektiivisesti siten, että lantion aluetta suonittava päävaltimo (arteria iliaca interna) tukitaan välittömästi. Näin vuoto saadaan nopeammin hallintaan ja potilaan selviytymisennuste paranee.
C-tyypin lantionmurtumien sisäinen kiinnitysmenetelmä, lantiorenkaan kiinnitys edestä levyin sekä takaa ruuvein tai levyin, osoittautui luotettavaksi (kolmas osajulkaisu). Saavutettu asento säilyi seurannassa erinomaisena tai hyvänä 90%:ssa tapauksista. Leikkauksessa saavutettu murtuman hyvä asento korreloi hyvään neurologiseen toipumiseen ja toiminnalliseen tulokseen. Epäanatominen tulos siten, että murtuman lopullinen siirtymä oli yli 5 mm, ennusti huonompaa toiminnallista lopputulosta. Merkittävin toimintakykyä rajoittava tekijä aiheutui lantion alueen hermopunosvauriosta. Tulokset tukevat käsitystä, jonka mukaan C-tyypin vammoissa tulee korjata ja kiinnittää kaikki murtumat lantiorenkaan etu- ja takaosassa, jolloin saavutetaan parempi anatominen tulos ja samalla parempi lantiorenkaan kokonaistukevuus.
Ristiluun H-tyypin murtuma, johon liittyy selkärangan ja lantiorenkaan irtoama toisistaan, on harvinainen lantion takaosan alueen vammakokonaisuus. Neljännessä osajulkaisussa käytetty lannerangan ja lantion välinen kiinnitysmenetelmä (lumbopelvinen kiinnitys) osoittautui luotettavaksi. Lantiohermopunoksen (alaraajojen osittainen halvaus) ja ristiluuhermojen vammat (ns. kauda equina syndrooma) ovat tähän vammatyyppiin liittyen yleisiä. Hermovaurion korjaantuminen ja kokonaistoipumisen ennuste oli riippuvainen ristiluun poikittaisen murtuman siirtymän asteesta. Hermovaurio oli vaikeampiasteinen ja toipumistulos huonompi, mikäli siirtymä ensimmäisessä kuvauksessa oli yli ristiluun paksuuden, kun tuloksia verrattiin siihen potilasryhmään, jolla siirtymä oli osittainen. Hyvä leikkauksessa saavutettu asento kaikissa ristiluun murtumalinjoissa oli yhteydessä parempaan toipumisennusteeseen.
Systemaattisella tutkimisella sekä määrätietoisella ja vaikuttavalla hoidolla voidaan vähentää lantiorenkaan murtumiin liittyvää kuolleisuutta, sairastavuutta ja pysyvää vammautumista
Mastering Endo-Laparoscopic and Thoracoscopic Surgery
This is an open access book. The book focuses mainly on the surgical technique, OR setup, equipments and devices necessary in minimally invasive surgery (MIS). It serves as a compendium of endolaparoscopic surgical procedures. It is an official publication of the Endoscopic and Laparoscopic Surgeons of Asia (ELSA). The book includes various sections covering basic skills set, devices, equipments, OR setup, procedures by area. Each chapter cover introduction, indications and contraindications, pre-operative patient’s assessment and preparation, OT setup (instrumentation required, patient’s position, etc.), step by step description of surgical procedures, management of complications, post-operative care. It includes original illustrations for better understanding and visualization of specific procedures. The book serves as a practical guide for surgical residents, surgical trainees, surgical fellows, junior surgeons, surgical consultants and anyone interested in MIS. It covers most of the basic and advanced laparoscopic and thoracoscopic surgery procedures meeting the curriculum and examination requirements of the residents
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