Development and application of a non invasive image matching method to study spine biomechanics

Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2008.Includes bibliographical references (p. 83-92).Research on spine biomechanics is critical to understand pathology such as degenerative changes and low back pain. However, current study on in-vivo spine biomechanics is limited by the complex anatomy and invasive methodology. Modem clinical imaging techniques such as magnetic resonance and fluoroscope images, which are widely accessible nowadays, have the potential to study in-vivo spine biomechanics accurately and non-invasively. This research presents a new combined magnetic resonance and fluoroscope imaging matching method to study human lumbar vertebral kinematics and disc deformation during various physiologic functional activities. Validation and application of this method as well as discussion of its performance and applicability are detailed herein.by Shaobai Wang.S.M

In vivo lumbar spine biomechanics : vertebral kinematics, intervertebral disc deformation, and disc loads

Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2012.Cataloged from PDF version of thesis.Includes bibliographical references.Knowledge of lumbar spine biomechanics in living human subjects is fundamental for understanding mechanisms of spinal injury and pathology, for improvement of corresponding clinical treatments, and for design of spinal prosthesis. However, due to the complicated spine anatomy and loading conditions as well as high risks in these direct measurements, it has been a challenge to determine the in vivo biomechanics of the lumbar spine. To address this problem, the overall objective of this thesis was to develop and implement a dual fluoroscopic imaging system to non-invasively study human lumbar spine biomechanics. In line with this objective, the first goal was to quantify the ability of the dual fluoroscopic imaging system to determine vertebral kinematics. The second goal was to implement this technique to investigate spinal motion in both healthy subjects and patients with pathology. The third goal was to explore the feasibility of using kinematic data obtained from this system as boundary conditions in finite element analysis to calculate the physiological loads on the intervertebral disc. The system was shown to be accurate and repeatable in determining the vertebral kinematics in all degrees of freedom. For the first time, six degree-of-freedom motion of different structures of the spine, such as the vertebral body, intervertebral disc, facet joint and spinous process were measured in vivo in both healthy subjects and subjects with pathology during functional activities. In general, the group of subjects with pathology showed a significantly abnormal kinematic response during various physiological functional activities. Preliminary studies have shown the applicability and high accuracy of finite element modeling to calculate disc loads using in vivo vertebral kinematics as displacement boundary conditions.by Shaobai Wang.Ph.D

Motion characteristics of the vertebral segments with lumbar degenerative spondylolisthesis in elderly patients

Objective Although some studies have reported on the kinematics of the lumbar segments with degenerative spondylolisthesis (DS), few data have been reported on the in vivo 6 degree-of-freedom kinematics of different anatomical structures of the diseased levels under physiological loading conditions. This research is to study the in vivo motion characteristics of the lumbar vertebral segments with L4 DS during weight-bearing activities. Methods Nine asymptomatic volunteers (mean age 54.4) and 9 patients with L4 DS (mean age 73.4) were included. Vertebral kinematics was obtained using a combined MRI/CT and dual fluoroscopic imaging technique. During functional postures (supine, standing upright, flexion, and extension), disc heights, vertebral motion patterns and instability were compared between the two groups. Results Although anterior disc heights were smaller in the DS group than in the normal group, the differences were only significant at standing upright. Posterior disc heights were significantly smaller in DS group than in the normal group under all postures. Different vertebral motion patterns were observed in the DS group, especially in the left–right and cranial–caudal directions during flexion and extension of the body. However, the range of motions of the both groups were much less than the reported criteria of lumbar spinal instability. Conclusion The study showed that lumbar vertebra with DS has disordered motion patterns. DS did not necessary result in vertebral instability. A restabilization process may have occurred and surgical treatment should be planned accordingly.China Scholarship CouncilNational Institutes of Health (U.S.) (R21AR057 989

Delayed Infrarenal Aortic Pseudoaneurysm Treated by Endovascular Stent Graft in Pyogenic Spondylitis

A 61-year-old male patient with pyogenic spondylodiscitis and epidural and psoas abscesses underwent posterior decompression, debridement, and instrumented fusion, followed by anterior debridement and reconstruction. Sudden onset flank pain was diagnosed 7 weeks postoperatively and was determined to be a pseudoaneurysm located at the aorta inferior to the renal artery and superior to the aortic bifurcation area. An endovascular stent graft was applied to successfully treat the pseudoaneurysm. Postoperative recovery was uneventful and infection status was stabilized

ABC block copolymer micelles driving the thermogelation:Scattering, imaging and spectroscopy

Thermoresponsive polymers have attracted much scientific attention due to their capacity for temperature-driven hydrogel formation. For biomedical applications, such as drug delivery, this transition should be tuned below body temperature to facilitate controlled and targeted drug release. We have recently developed a thermoresponsive polymer that forms gel at low concentrations (2 w/w%) in aqueous media and offers a cost-effective alternative to thermoresponsive systems currently being applied in clinics. This polymer is an ABC triblock terpolymer, where A, B, and C correspond to oligo(ethylene glycol) methyl ether methacrylate with average Mn 300 g mol−1 (OEGMA300), n-butyl methacrylate (BuMA), and di(ethylene glycol) methyl ether methacrylate (DEGMA). To investigate the self-assembly and the gelation mechanism in diluted solutions, we used small-angle neutron scattering (SANS) on 1 w/w% (below the gelation concentration) and 5 w/w% solutions (above the gelation concentration). As a comparison, we also investigated the solutions of the most studied thermoresponsive polymer, namely, Pluronic F127, an ABA triblock bipolymer made of ethylene glycol (A) and propylene glycol (B) blocks. SANS revealed that the in-house synthesised polymer forms elliptical cylinders, whose length increases significantly with temperature. In contrast, Pluronic F127 solutions form core-shell spherical micelles, which slightly elongate with temperature. Transmission electron microscopy images support the SANS findings, with tubular/worm structures being present. Variable-temperature circular dichroism (CD) and proton nuclear magnetic resonance (1H NMR) spectroscopy experiments reveal insights on the tacticity, structural changes, and molecular origin of the self-assembly

Alterações no funcionamento cardíaco registadas por eletrocardiograma após acupuntura

Trabalho final de mestrado integrado em Medicina área científica de Acupuntura, apresentado á Faculdade de Medicina da Universidade de CoimbraUma hiperatividade no sistema nervoso simpático e/ou uma depressão no sistema nervoso parassimpático pode estar na origem de diversas doenças cardíacas. Vários estudos anteriores mostraram possíveis efeitos de acupuntura na regulação do sistema nervoso autónomo no Homem. O presente estudo avaliou os potenciais efeitos da acupuntura especificamente ao nível do sistema vegetativo cardíaco, por meio de eletrocardiograma (EKG). Os pontos escolhidos para o presente estudo foram: 03CO (Shao Hai), 07CO (Shen Men), 06PE (Nei Guan), DU20 (Bai Hui) e Yin Tang, que possuem, de uma forma geral, efeitos tranquilizantes e analgésicos. Em cada indivíduo foram obtidos três EKGs ao longo de um período de 15 dias. As quatro sessões de acupuntura, sendo cada uma de 20 minutos, foram praticadas durante o primeiro e o segundo EKG. A seguir, foram medidos os valores de amplitude e de duração das ondas P e T e do complexo QRS em cada EKG ao nível de derivação II. Os valores médios de cada parâmetro obtidos dos três EKGs de um mesmo indivíduo, após tratamento estatístico adequado, foram comparados, visando detetar possíveis alterações entre si. Os resultados obtidos indicaram que a acupuntura tinha exercido um efeito significativo sobre o funcionamento cardíaco. No entanto, era expetável haver vários mecanismos subjacentes a estas alterações devido ao facto de haver alguns resultados contraditórios na amostra. Estudos futuros serão necessários para compreender melhor os possíveis mecanismos subjacentesA hyperactivity in the sympathetic nervous system and/or a depression in the parasympathetic nervous system may be the cause of various heart diseases. Many previous studies have shown possible effects of acupuncture in terms of regulating the autonomic nervous system of the human body. The present study analyzed some potential effects of acupuncture, specifically its potencial effects to the cardiac autonomic nervous system. The present study was conducted by means of electrocardiogram (EKG). The acupuncture points that we choose in this study were: 03CO (Shao Hai) 07CO (Shen Men), 06PE (Nei Guan) DU20 (Bai Hui) and Yin Tang. Generally speaking, experiments conducted upon these selected points have shown effects of tranquilization, sedation, and analgesia to the human body. For each volunteer, we conducted three times of EKG and four sessions of acupuncture during a period of 15 days. Each acupuncture session is 20 minutes long and all the four sessions are conducted between the first and second EKG. After obtaining all the experimental results, we measured the amplitude and duration of the waves P and T and of the QRS complex for each EKG, using the lead II. We compared the averages of each parameter in order to detect some possible changes. The results showed that acupuncture had a significant effect on cardiac function. However, there might have been some other mechanisms underlying these changes, and more future studies are needed for the better understand of those possible underlying mechanism

Simulation of Unsteady Flows of Oil/Gas in the Ventless Bearing Chamber of an Aero-Engine

The unsteady motion behavior of oil/gas two-phase flow in a novel ventless bearing chamber has significant impacts on the lubrication and heat transfer efficiency of bearings due to the various advantages of lower pressure levels and weaker rotating airflow effects. In this paper, the unsteady motion behavior of oil/gas two-phase flow in a ventless aero-engine bearing chamber is investigated by three-dimensional numerical simulation through the volume of fluid (VOF) method, and the numerical method is verified using published experimental data. The flow characteristics of oil/gas two-phase in the secondary flow and three-dimensional flow are investigated. The results show the evolution of vortices and the transition of the driving mode in the unsteady motion of oil/gas two-phase flow, and a criterion for the shift of the driving mode at different rotor speeds is proposed. As the rotation speed increases, the variation trend of the velocity field and pressure field of oil/gas two-phase flow is consistent, and the accumulation region of oil becomes inconspicuous. The results indicate a reference for enhancing the performance of lubrication systems for aero-engines

Proning Bed for the Intensive Care Unit

Capstone Design and Manufacturing Experience: Winter 2006Acute respiratory distress syndrome is a severe lung dysfunction that requires treatment involving a technique known as pronation therapy. Medical studies and practice have shown this therapy to be beneficial in patient recovery. Unfortunately, the procedure introduces risks for both the patient and nursing staff. Various devices currently available in the market are largely cumbersome, expensive, and inadequate. As a result, the University of Michigan Hospital uses a manual proning process. This requires demanding tasks from a well trained nursing staff. Also, in smaller hospitals, many patients are denied pronation due to the lack of financial resources and staffing experience. The objective of this project is to design and prototype a device that will facilitate the proning process. This can be achieved by making the process safer for the patient, or by making the process easier for the nursing staff without compromising patient safety. Our work on this project is complete, but further design modifications and testing are necessary to market the product.Mary-Anne Purtill, M.D., Surgical Critical Care ME 450http://deepblue.lib.umich.edu/bitstream/2027.42/49585/2/proj4_report.pd

Synthesis of some new biflavonoids. I. Synthesis of the aromatic 1,4-diketones

Five arom. 1,4-diketones I [R = 2,4,6-(MeO)3, H, 4-Me, 4-MeO, 2,4-(MeO)2] were prepd. using succinyl chloride as acylating reagent. Arom. 1,4-diketone I [R = 2,4,6-(MeO)3] was also prepd. by using succinic anhydride as acylating reagent. The first method could be used for the prepn. of arom. 1,4-diketones with the same arom. groups, and the second for the different arom. groups. [on SciFinder (R)

Acute effect of foot strike patterns on in vivo tibiotalar and subtalar joint kinematics during barefoot running

Background: Foot kinematics, such as excessive eversion and malalignment of the hindfoot, are believed to be associated with running-related injuries. The majority of studies to date show that different foot strike patterns influence these specific foot and ankle kinematics. However, technical deficiencies in traditional motion capture approaches limit knowledge of in vivo joint kinematics with respect to rearfoot and forefoot strike patterns (RFS and FFS, respectively). This study uses a high-speed dual fluoroscopic imaging system (DFIS) to determine the effects of different foot strike patterns on 3D in vivo tibiotalar and subtalar joints kinematics. Methods: Fifteen healthy male recreational runners underwent foot computed tomography scanning for the construction of 3-dimensional models. A high-speed DFIS (100 Hz) was used to collect 6 degrees of freedom kinematics for participants’ tibiotalar and subtalar joints when they adopted RFS and FFS in barefoot condition. Results: Compared with RFS, FFS exhibited greater internal rotation at 0%–20% of the stance phase in the tibiotalar joint. The peak internal rotation angle of the tibiotalar joint under FFS was greater than under RFS (p < 0.001, Cohen's d = 0.92). RFS showed more dorsiflexion at 0%–20% of the stance phase in the tibiotalar joint than FFS. RFS also presented a larger anterior translation (p < 0.001, Cohen's d = 1.28) in the subtalar joint at initial contact than FFS. Conclusion: Running with acute barefoot FFS increases the internal rotation of the tibiotalar joint in the early stance. The use of high-speed DFIS to quantify the movement of the tibiotalar and subtalar joint was critical to revealing the effects of RFS and FFS during running