scholarly journals Computer Simulation and Analysis on Flow Characteristics and Distribution Patterns of Polymethylmethacrylate in Lumbar Vertebral Body and Vertebral Pedicle

2015 ◽  
Vol 2015 ◽  
pp. 1-8 ◽  
Author(s):  
Da Liu ◽  
Xu-li Liu ◽  
Bo Zhang ◽  
Dong-fa Liao ◽  
Zhi-qiang Li ◽  
...  
Keyword(s):  
Computer Simulation ◽  
Computational Model ◽  
Vertebral Body ◽  
Silicone Oil ◽  
Lumbar Vertebrae ◽  
Flow Characteristics ◽  
Electron Beam Tomography ◽  
Injection Point ◽  
Lumbar Vertebral Body ◽  
Pmma Bone Cement

This study was designed to analyze the flow and distribution of polymethylmethacrylate (PMMA) in vertebral body through computer simulation. Cadaveric lumbar vertebrae were scanned through electron beam tomography (EBT). The data was imported into Mimics software to build computational model. Vertebral body center and junction of pedicle and vertebral body were chosen as injection points. Silicone oil with viscosity of 100,000 cSt matching with PMMA bone cement was chosen for injection. The flow and distribution of silicone oil were analyzed using Fluent software. In vertebral body, silicone oil formed a circle-like shape centered by injection point on transverse and longitudinal sections, finally forming a sphere-like shape as a whole. Silicone oil diffused along lateral and posterior walls forming a circle-like shape on transverse section centered by injection point in pedicle, eventually forming a sphere-like shape as a whole. This study demonstrated that silicone oil flowed and diffused into a circle-like shape centered by injection point and finally formed a sphere-like shape as a whole in both vertebral body and pedicle. The flow and distribution of silicon oil in computational model could simulate PMMA distribution in vertebral body. It may provide theoretical evidence to reduce PMMA leakage risk during percutaneous vertebroplasty.

Viscous Oil-Water Flow in a Microchannel: Flow Patterns and Flow Development

2010 ◽  
Author(s):  
Hooman Foroughi ◽  
Masahiro Kawaji
Keyword(s):  
Water Flow ◽  
Silicone Oil ◽  
Flow Characteristics ◽  
Flow Patterns ◽  
Fused Silica ◽  
Water Mixture ◽  
Injection Point ◽  
Viscous Oil ◽  
Wide Range ◽  
Oil Water

The flow characteristics of a highly viscous oil and water mixture in a circular microchannel have been investigated. Water and silicone oil with a viscosity of 863 mPa.s were injected into a fused silica microchannel with a diameter of 250 μm. Before each experiment, the microchannel was initially saturated with either oil or water. In the initially oil-saturated case, different liquid-liquid flow patterns were observed and classified over a wide range of oil and water flow rates. As a special case, the flow of water at zero oil flow rate in a microchannel initially filled with silicone oil was also studied. When the microchannel was initially saturated with water, the oil formed a jet in water at the injection point but developed an instability at the oil-water interface downstream and eventually broke up into droplets.

scholarly journals The Finite Element Analysis of Osteoporotic Lumbar Vertebral Body by Influence of Trabecular Bone Apparent Density and Thickness of Cortical Shell

2017 ◽  
Vol 11 (4) ◽  
pp. 285-292 ◽  
Author(s):  
Oleg Ardatov ◽  
Algirdas Maknickas ◽  
Vidmantas Alekna ◽  
Marija Tamulaitienė ◽  
Rimantas Kačianauskas
Keyword(s):  
Vertebral Body ◽  
Cancellous Bone ◽  
Apparent Density ◽  
Yield Criterion ◽  
Nonlinear Dynamic Analysis ◽  
Lumbar Vertebrae ◽  
Element Analysis ◽  
Bone Mass Loss ◽  
Lumbar Vertebral Body ◽  
Cortical Shell

AbstractOsteoporosis causes the bone mass loss and increased fracture risk. This paper presents the modelling of osteoporotic human lumbar vertebrae L1 by employing finite elements method (FEM). The isolated inhomogeneous vertebral body is composed by cortical out-er shell and cancellous bone. The level of osteoporotic contribution is characterised by reducing the thickness of cortical shell and elasticity modulus of cancellous bone using power-law dependence with apparent density. The strength parameters are evaluated on the basis of von Mises-Hencky yield criterion. Parametric study of osteoporotic degradation contains the static and nonlinear dynamic analysis of stresses that occur due to physiological load. Results of our investigation are presented in terms of nonlinear interdependence between stress and external load.

Effect of CT-based attenuation correction on uptake ratios in skeletal SPECT

2007 ◽  
Vol 46 (01) ◽  
pp. 38-42 ◽  
Author(s):  
V. Schulz ◽  
I. Nickel ◽  
A. Nömayr ◽  
A. H. Vija ◽  
C. Hocke ◽  
...  
Keyword(s):  
Vertebral Body ◽  
Facet Joint ◽  
One Dimension ◽  
Patient Specific ◽  
Data Sets ◽  
Facet Joints ◽  
Lumbar Vertebral Body ◽  
Ct System ◽  
Ct Data ◽  
Attenuation Corrected

SummaryThe aim of this study was to determine the clinical relevance of compensating SPECT data for patient specific attenuation by the use of CT data simultaneously acquired with SPECT/CT when analyzing the skeletal uptake of polyphosphonates (DPD). Furthermore, the influence of misregistration between SPECT and CT data on uptake ratios was investigated. Methods: Thirty-six data sets from bone SPECTs performed on a hybrid SPECT/CT system were retrospectively analyzed. Using regions of interest (ROIs), raw counts were determined in the fifth lumbar vertebral body, its facet joints, both anterior iliacal spinae, and of the whole transversal slice. ROI measurements were performed in uncorrected (NAC) and attenuation-corrected (AC) images. Furthermore, the ROI measurements were also performed in AC scans in which SPECT and CT images had been misaligned by 1 cm in one dimension beforehand (ACX, ACY, ACZ). Results: After AC, DPD uptake ratios differed significantly from the NAC values in all regions studied ranging from 32% for the left facet joint to 39% for the vertebral body. AC using misaligned pairs of patient data sets led to a significant change of whole-slice uptake ratios whose differences ranged from 3,5 to 25%. For ACX, the average left-to-right ratio of the facet joints was by 8% and for the superior iliacal spines by 31% lower than the values determined for the matched images (p <0.05). Conclusions: AC significantly affects DPD uptake ratios. Furthermore, misalignment between SPECT and CT may introduce significant errors in quantification, potentially also affecting leftto- right ratios. Therefore, at clinical evaluation of attenuation- corrected scans special attention should be given to possible misalignments between SPECT and CT.

scholarly journals Determination of receiver consumption characteristics using computer simulation

2020 ◽  
Vol 8 (2) ◽  
pp. 10-14
Author(s):  
S.S. Vasyliv ◽  
◽  
V.S. Zhdanov ◽  
M.V. Yevseyenko ◽  
◽  
...  
Keyword(s):  
Computer Simulation ◽  
Flow Rate ◽  
Rocket Engine ◽  
Flow Characteristics ◽  
Maximum Flow ◽  
Complex Configuration ◽  
Rocket Engines ◽  
Gas Leakage ◽  
Control Forces ◽  
Firing Tests

The problem of implementing the detonation mode of fuel combustion in thermal propulsion systems has been widely studied last decade. There are many works on fundamental and applied research on pulsating detonation. Solid propellant detonation engines can develop significant forces for a short time at low structural masses, and therefore they are ideal for auxiliary systems for the removal of separated rocket parts. In addition, detonation processes can be used to create control forces for correcting the trajectory of aircraft. All these facts determine the relevance of the area of work. For studying detonation installations, it is necessary to create test stands, but the design of test installations is an urgent and complex optimization problem. It is advisable to solve this problem with the help of computer simulation. In the existing experimental methods, for designing, it is necessary to determine in advance the geometric parameters of receivers and pipelines that provide the necessary gas consumption for firing tests of detonation rocket engines. The work is devoted to the development of a method for determining the flow characteristics of a receiver with a pipeline of complex configuration based on the constructed model of the stand. Based on the initial data, a computer simulation of the air leakage process from the receiver was carried out, for which the Solid Works software package was used. The places of pressure drop, maximum flow rate, and air mass flow are determined. The low value of the flow rate factor is due to the complex configuration of the pipeline with numerous bends and two bellows. Comparison of calculation results with experimental data was held. The difference between the experimental and calculated values does not exceed 3.6%. The obtained information is used to select the required value of the oxidizer excess coefficient during firing tests of detonation rocket engine models. Keywords: flow rate, gas leakage, receiver, model.

scholarly journals The human lumbar vertebral body as an intrinsic, functionally optimal structure

2007 ◽  
Vol 1 (1) ◽  
pp. 34-47
Author(s):  
D.N. Ghista ◽  
S.C. Fan ◽  
K. Ramakrishna ◽  
I. Sridhar
Keyword(s):  
Vertebral Body ◽  
Optimal Structure ◽  
Lumbar Vertebral Body

scholarly journals Transesophageal endoscopic ultrasound fine needle aspiration of vertebral body osteolytic tumors – a novel diagnostic approach. Case series.

2020 ◽  
Author(s):  
Romeo Ioan Chira ◽  
Alina Florea ◽  
Vlad Ichim ◽  
Liliana Rogojan ◽  
Alexandra Chira ◽  
...  
Keyword(s):  
Vertebral Body ◽  
Endoscopic Ultrasound ◽  
Fine Needle Aspiration ◽  
Histopathological Examination ◽  
Traditional Approach ◽  
Case Series ◽  
Lumbar Vertebrae ◽  
Needle Aspiration ◽  
Ct Guided ◽  
Fine Needle

Aims: Vertebral lesions, either primary or more frequently metastasis, are difficult targets for percutaneous guided biopsies and surgical biopsies and are associated with greater risks of complications. We investigated the feasibility of endoscopic ultrasound (EUS) fine needle aspiration (FNA) biopsy in the assessment of vertebral osteolytic tumors as an alternative to CT guided biopsy which is the technique currently used.Material and methods: Four patients with osteolytic tumors of the vertebral bodies identified by imaging methods (CT or MRI) – 3 patients, and one with a tumor detected primarily during EUS procedure were included in order to evaluate the feasibility of the procedure. The lesions were located either at the dorsal or lumbar vertebrae. In all cases we performed EUS FNA of the osteolytic vertebral body lesions with 22G needles using the transesophageal or transgastric approach.Results: In all cases EUS FNA provided enough tissue for an accurate histopathological report, with no procedural complication. We diagnosed lung adenocarcinoma, hepatocarcinoma and a pancreatic adenocarcinoma vertebral metastasis and one case of lymphoma.Conclusions: EUS FNA is a valuable technique which should be considered in selected cases, when a “traditional approach” is not applicable or associated with a higher risk. Treatment guidelines are based on the histology of the tumor, histopathological examination being nowadays mandatory. Therefore, we propose for selected cases a feasible technique, with significantly lower procedural risks, as an alternative for open surgical biopsies or computed tomography guided biopsies

CONSIDERATION OF BUOYANCE FORCES WHEN SIMULATING SUPERCRITICAL WATER FLOW IN VERTICAL TUBES

2017 ◽  
Author(s):  
Nataliia Fialko ◽  
◽  
Julii Sherenkovskiy ◽  
Nataliia Meranova ◽  
Serhii Aleshko ◽  
...  
Keyword(s):  
Computer Simulation ◽  
Water Flow ◽  
Supercritical Water ◽  
Flow Characteristics ◽  
Buoyancy Forces ◽  
Vertical Tubes

The results of computer simulation of supercritical water flow in tubes are presented. The regularities of the influence of buoyancy forces on the flow characteristics are investigated.

Anatomy of the Spinal Cord

2021 ◽  
pp. 60-67
Author(s):  
Jennifer A. Tracy
Keyword(s):  
Spinal Cord ◽  
Vertebral Body ◽  
Spinal Canal ◽  
Conus Medullaris ◽  
Lower Limbs ◽  
Cervical Cord ◽  
Filum Terminale ◽  
Upper Limbs ◽  
Descending Pathways ◽  
Lumbar Vertebral Body

The spinal cord begins as the cervical cord immediately below the medulla and extends through the spinal canal, where it becomes the thoracic, lumbar, sacral, and coccygeal parts of the cord. In most persons, the spinal cord proper ends at the lower portion of the first lumbar vertebral body, where it forms the conus medullaris and, finally, the filum terminale. A cervical enlargement contains the innervation pathways of the upper limbs; a lumbar enlargement contains the pathways of the lower limbs. This chapter reviews ascending and descending pathways in the spinal cord.

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