Improved Understanding of Stent Malapposition Using Virtual Bench Testing

2011 ◽  
Vol 6 (2) ◽  
pp. 106 ◽  
Author(s):  
Peter Mortier ◽  
Heleen MM van Beusekom ◽  
Matthieu De Beule ◽  
Ilona Krabbendam-Peters ◽  
Benjamin Van Der Smissen ◽  
...  
Keyword(s):  
Imaging Techniques ◽  
Average Distance ◽  
Three Dimensional ◽  
Proximal Part ◽  
New Approach ◽  
Incomplete Stent Apposition ◽  
Bifurcation Stenting ◽  
Silicone Model ◽  
Bench Testing

Intravascular imaging techniques such as optical coherence tomography (OCT) and intravascular ultrasound (IVUS) are often used to assess strut apposition, but only provide limited insight into the three-dimensional appositioning behaviour of stents. Recently, a new approach has been introduced to study the phenomenon of incomplete stent apposition (ISA) based on finite element simulations. In this study, we employed this virtual strut apposition assessment technique in the setting of coronary bifurcation stenting and compared simulated strut–artery distances of two stent designs with actual measurements based on OCT imaging using a silicone model. Stenting of the main branch leads to malapposed struts in the proximal part and the average strut–artery distance in that region for the Integrity stent is 126 μm based on the simulation and 117±14 μm based on the OCT analysis. For the Multi-Link 8 stent, this average distance is 150 μm and 174±7 µm for the simulation and thein vitroOCT measurements respectively. In conclusion, the virtual assessment of strut appositioning results in similar strut–artery distances when compared with measurements based on OCT-visualisedin vitrostent deployments and could be used to optimise devices and procedures.

scholarly journals Sensitivity analysis of FDA´s benchmark nozzle regarding in vitro imperfections - Do we need asymmetric CFD benchmarks?

2020 ◽  
Vol 6 (3) ◽  
pp. 78-81
Author(s):  
Michael Stiehm ◽  
Christoph Brandt-Wunderlich ◽  
Stefan Siewert ◽  
Klaus-Peter Schmitz ◽  
Niels Grabow ◽  
...  
Keyword(s):  
Reynolds Number ◽  
Flow Field ◽  
In Silico ◽  
Nozzle Geometry ◽  
Geometrical Imperfection ◽  
Custom Made ◽  
Inlet Conditions ◽  
Silicone Model ◽  
Bench Testing

AbstractModern technologies and methods such as computer simulation, so-called in silico methods, foster the development of medical devices. For accelerating the uptake of computer simulations and to increase credibility and reliability the U.S. Food and Drug Administration organized an inter-laboratory round robin study of a generic nozzle geometry. In preparation of own bench testing experiment using Particle Image Velocimetry, a custom made silicone nozzle was manufactured. By using in silico computational fluid dynamics method the influence of in vitro imperfections, such as inflow variations and geometrical deviations, on the flow field were evaluated. Based on literature the throat Reynolds number was varied Rethroat = 500 ± 50. It could be shown that the flow field errors resulted from variations of inlet conditions can be largely eliminated by normalizing if the Reynolds number is known. Furthermore, a symmetric imperfection of the silicone model within manufacturing tolerance does not affect the flow as much as an asymmetric failure such as an unintended curvature of the nozzle. In brief, we can conclude that geometrical imperfection of the reference experiment should be considered accordingly to in silico modelling. The question arises, if an asymmetric benchmark for biofluid analysis needs to be established. An eccentric nozzle benchmark could be a suitable case and will be further investigated.

scholarly journals New approach for T-shaped uterus: Metroplasty with resection of lateral fibromuscular tissue using a 15 Fr miniresectoscope. A step-by-step technique.

2021 ◽  
Vol 13 (1) ◽  
pp. 67-71
Author(s):  
U. Catena ◽  
R. Campo ◽  
G. Bolomini ◽  
M.C. Moruzzi ◽  
V. Verdecchia ◽  
...  
Keyword(s):  
Surgical Technique ◽  
Recurrent Miscarriage ◽  
Three Dimensional ◽  
Uterine Cavity ◽  
In Vitro Fertilisation ◽  
Step Method ◽  
New Approach ◽  
Uterine Malformation ◽  
New Surgical Technique

T-shaped uterus is a congenital uterine malformation (CUM), only recently defined by the ESGE ESHRE classification as Class U1a. The uterus is characterised by a narrow uterine cavity due to thickened lateral walls with a correlation 2/3 uterine corpus and 1/3 cervix (Grimbizis et al, 2013). Although the significance of this dysmorphic malformation on reproductive performance has been questioned, recent studies reported significant improvement of life birth rates after surgical correction in patients with failed in-vitro fertilisation (IVF) or recurrent miscarriage (Ferro et al, 2018; Di Spiezio Sardo et al, 2020; Alonso Pacheco et al. 2019). The classical surgical technique to treat a T-shaped uterus is by performing a sidewall incision with the micro scissor or bipolar needle, resulting in a triangular cavity. In this video article, we describe a new surgical technique with a step-by-step method combining three-dimensional ultrasound (3D-US) and hysteroscopic metroplasty in an office setting, using a 15 Fr office resectoscope (Karl Storz, Tuttlingen, Germany), to treat a T-shaped uterus by resecting the lateral fibromuscular tissue of the uterine walls. No complications occurred and the postoperative hysteroscopy showed a triangular and symmetrical uterine cavity without any adhesions.

scholarly journals Patient-Specific Aortic Phantom With Tunable Compliance

2019 ◽  
Vol 2 (4) ◽  
Author(s):  
Antonio Gallarello ◽  
Andrea Palombi ◽  
Giacomo Annio ◽  
Shervanthi Homer-Vanniasinkam ◽  
Elena De Momi ◽  
...  
Keyword(s):  
Aortic Arch ◽  
Computational Models ◽  
Three Dimensional ◽  
Complex Interventions ◽  
Patient Specific ◽  
Arch Model ◽  
Magnetic Resonance Imaging Mri ◽  
Variable Wall ◽  
Silicone Model

Abstract Validation of computational models using in vitro phantoms is a nontrivial task, especially in the replication of the mechanical properties of the vessel walls, which varies with age and pathophysiological state. In this paper, we present a novel aortic phantom reconstructed from patient-specific data with variable wall compliance that can be tuned without recreating the phantom. The three-dimensional (3D) geometry of an aortic arch was retrieved from a computed tomography angiography scan. A rubber-like silicone phantom was manufactured and connected to a compliance chamber in order to tune its compliance. A lumped resistance was also coupled with the system. The compliance of the aortic arch model was validated using the Young's modulus and characterized further with respect to clinically relevant indicators. The silicone model demonstrates that compliance can be finely tuned with this system under pulsatile flow conditions. The phantom replicated values of compliance in the physiological range. Both, the pressure curves and the asymmetrical behavior of the expansion, are in agreement with the literature. This novel design approach allows obtaining for the first time a phantom with tunable compliance. Vascular phantoms designed and developed with the methodology proposed in this paper have high potential to be used in diverse conditions. Applications include training of physicians, pre-operative trials for complex interventions, testing of medical devices for cardiovascular diseases (CVDs), and comparative Magnetic-resonance-imaging (MRI)-based computational studies.

scholarly journals A MATLAB-based program for three-dimensional quantitative analysis of micronuclei reveals that neuroinflammation induces micronuclei formation in the brain

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Sarasa Yano ◽  
Kaito Akiyama ◽  
Rio Tsuchiya ◽  
Hikari Kubotani ◽  
Tomoki Chiba ◽  
...  
Keyword(s):  
Imaging Techniques ◽  
Three Dimensional ◽  
Innate Immune ◽  
The Other ◽  
Primary Neurons ◽  
Immune Response Pathway ◽  
The Brain ◽  
Quantitative Procedure

AbstractThe micronucleus is known to be a biomarker for genomic instability, which is a hallmark of tumors and aging. Normally, micronuclei are produced by segregation errors and mechanical stresses arising from dividing or migrating cells, leading to activation of the innate immune response pathway. Although micronuclei often emerge in damaged tissues, the quantitative procedure for analyzing micronuclei accurately has been problematic. Here, we introduce a novel MATLAB-based program for quantifying micronuclei (CAMDi: calculating automatic micronuclei distinction) in vitro and in vivo. CAMDi is adaptable to various experimental imaging techniques and is useful for obtaining reproducible data. CAMDi enables us to measure the accurate size of micronuclei from the three-dimensional images. Using CAMDi, we revealed a novel link between the emergence of micronuclei and neuroinflammation. We found that inflammatory stimulation does not increase the number of micronuclei in primary neurons. On the other hand, the administration of lipopolysaccharide into mice slightly increases micronuclei formation in neurons of the hippocampus region. These findings demonstrate that neuronal micronuclei formations are induced by an inflammatory response in a non-cell-autonomous manner. We provide a novel tool, CAMDi, to quantify micronuclei and demonstrate that neuronal micronuclei are produced not only by the cell-autonomous process but also by the intercellular communication associated with neuroinflammation in vivo.

Coronary bifurcation stenting: insights from in vitro and virtual bench testing

2010 ◽  
Vol 6 (J) ◽  
pp. J53-J60 ◽  
Author(s):  
Peter Mortier ◽  
Matthieu De Beule ◽  
Gabriele Dubini ◽  
Yutaka Hikichi ◽  
Yoshinobu Murasato ◽  
...  
Keyword(s):  
Coronary Bifurcation ◽  
Bifurcation Stenting ◽  
Bench Testing

scholarly journals New Stenting Technique to Achieve Favorable Jailing Configuration on Side Branch Ostium: Bent Stent Technique

2016 ◽  
Vol 2016 ◽  
pp. 1-4
Author(s):  
Fumiaki Nakao
Keyword(s):  
Optical Coherence Tomography ◽  
Three Dimensional ◽  
Side Branch ◽  
Optical Coherence ◽  
Coronary Bifurcation ◽  
First Report ◽  
Incomplete Stent Apposition ◽  
Bifurcation Stenting ◽  
Distal Cell

According to data from stent-enhanced three-dimensional optical coherence tomography, incomplete stent apposition after side branch dilation in coronary bifurcation stenting can be reduced by the free carina type (no links bridged from a carina) and by distal cell rewiring. This is the first report to describe a bent stent technique that was devised to achieve the free carina type (no links bridged from a carina), as a favorable jailing configuration.

scholarly journals A Cleared View on Retinal Organoids

Cells ◽  
2019 ◽  
Vol 8 (5) ◽  
pp. 391 ◽  
Author(s):  
Virginia Cora ◽  
Jasmin Haderspeck ◽  
Lena Antkowiak ◽  
Ulrich Mattheus ◽  
Peter Neckel ◽  
...  
Keyword(s):  
High Resolution ◽  
Imaging Techniques ◽  
Three Dimensional ◽  
Induced Pluripotent Stem Cell ◽  
Basic Research ◽  
Photoreceptor Cells ◽  
Bipolar Cells ◽  
Human Organ ◽  
Ribbon Synapses

Human induced pluripotent stem cell (hiPSC)-derived organoids mimicking tissues and organs in vitro have advanced medical research, as they opened up new possibilities for in-depth basic research on human organ development as well as providing a human in vitro model for personalized therapeutic approaches. hiPSC-derived retinal organoids have proven to be of great value for modeling the human retina featuring a very similar cellular composition, layering, and functionality. The technically challenging imaging of three-dimensional structures such as retinal organoids has, however, raised the need for robust whole-organoid imaging techniques. To improve imaging of retinal organoids we optimized a passive clearing technique (PACT), which enables high-resolution visualization of fragile intra-tissue structures. Using cleared retinal organoids, we could greatly enhance the antibody labeling efficiency and depth of imaging at high resolution, thereby improving the three-dimensional microscopy output. In that course, we were able to identify the spatial morphological shape and organization of, e.g., photoreceptor cells and bipolar cell layers. Moreover, we used the synaptic protein CtBP2/Ribeye to visualize the interconnection points of photoreceptor and bipolar cells forming the retinal-specific ribbon synapses.

scholarly journals A Technique for Quantifying Wrist Motion Using Four-Dimensional Computed Tomography: Approach and Validation

2015 ◽  
Vol 137 (7) ◽  
Author(s):  
Kristin Zhao ◽  
Ryan Breighner ◽  
David Holmes ◽  
Shuai Leng ◽  
Cynthia McCollough ◽  
...  
Keyword(s):  
Computed Tomography ◽  
Imaging Techniques ◽  
Three Dimensional ◽  
Three Dimensions ◽  
Ligament Injury ◽  
Imaging Biomarkers ◽  
Clinical Implementation ◽  
Position Information ◽  
Wrist Motion

Accurate quantification of subtle wrist motion changes resulting from ligament injuries is crucial for diagnosis and prescription of the most effective interventions for preventing progression to osteoarthritis. Current imaging techniques are unable to detect injuries reliably and are static in nature, thereby capturing bone position information rather than motion which is indicative of ligament injury. A recently developed technique, 4D (three dimensions + time) computed tomography (CT) enables three-dimensional volume sequences to be obtained during wrist motion. The next step in successful clinical implementation of the tool is quantification and validation of imaging biomarkers obtained from the four-dimensional computed tomography (4DCT) image sequences. Measures of bone motion and joint proximities are obtained by: segmenting bone volumes in each frame of the dynamic sequence, registering their positions relative to a known static posture, and generating surface polygonal meshes from which minimum distance (proximity) measures can be quantified. Method accuracy was assessed during in vitro simulated wrist movement by comparing a fiducial bead-based determination of bone orientation to a bone-based approach. The reported errors for the 4DCT technique were: 0.00–0.68 deg in rotation; 0.02–0.30 mm in translation. Results are on the order of the reported accuracy of other image-based kinematic techniques.

scholarly journals Arabidopsis Carboxylesterase 20 Binds Strigolactone and Increases Branches and Tillers When Ectopically Expressed in Arabidopsis and Maize

2021 ◽  
Vol 12 ◽  
Author(s):  
Keith Roesler ◽  
Cheng Lu ◽  
Jill Thomas ◽  
Qingzhang Xu ◽  
Peter Vance ◽  
...  
Keyword(s):  
Ectopic Expression ◽  
Three Dimensional ◽  
Binding Pocket ◽  
Transgenic Maize ◽  
Severe Drought ◽  
3D Protein Structure ◽  
New Approach ◽  
Delayed Senescence ◽  
Hydrophobic Binding

Severe drought stress can delay maize silk emergence relative to the pollen shedding period, resulting in poor fertilization and reduced grain yield. Methods to minimize the delay in silking could thus improve yield stability. An Arabidopsis enhancer-tagged carboxylesterase 20 (AtCXE20) line was identified in a drought tolerance screen. Ectopic expression of AtCXE20 in Arabidopsis and maize resulted in phenotypes characteristic of strigolactone (SL)-deficient mutants, including increased branching and tillering, decreased plant height, delayed senescence, hyposensitivity to ethylene, and reduced flavonols. Maize silk growth was increased by AtCXE20 overexpression, and this phenotype was partially complemented by exogenous SL treatments. In drought conditions, the transgenic maize plants silked earlier than controls and had decreased anthesis-silking intervals. The purified recombinant AtCXE20 protein bound SL in vitro, as indicated by SL inhibiting AtCXE20 esterase activity and altering AtCXE20 intrinsic fluorescence. Homology modeling of the AtCXE20 three-dimensional (3D) protein structure revealed a large hydrophobic binding pocket capable of accommodating, but not hydrolyzing SLs. The AtCXE20 protein concentration in transgenic maize tissues was determined by mass spectrometry to be in the micromolar range, well-above known endogenous SL concentrations. These results best support a mechanism where ectopic expression of AtCXE20 with a strong promoter effectively lowers the concentration of free SL by sequestration. This study revealed an agriculturally important role for SL in maize silk growth and provided a new approach for altering SL levels in plants.

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