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2.
Br J Radiol ; 93(1112): 20200204, 2020 Aug.
Artículo en Inglés | MEDLINE | ID: mdl-32525696

RESUMEN

OBJECTIVES: Evaluation of performance and forensic relevance of a novel, photorealistic, 3D reconstruction method (cinematic rendering, (CR)) in comparison with conventional post-mortem CT (PMCT) and volume rendering (VR) technique for visualization of traumatic injuries. METHODS: 112 pathologies (fractures, soft tissue injuries and foreign bodies) from 33 human cadavers undergoing whole body PMCT after traumatic death were retrospectively analyzed. Pathologies were reconstructed with CR and VR techniques. Fractures were classified according to their dislocation. Images were evaluated according to their expressiveness and judicial relevance by two forensic pathologists using a five-level Likert-scale (1: high expressiveness, 5: low expressiveness). They decided whether CR reconstructions were suitable for judicial reviews. The detection rate of pathologies was determined by two radiologists. RESULTS: CR was more expressive than VR for all three trauma categories (p < 0.01) and than conventional CT when used for fractures with dislocation (p < 0.001), injuries of the ventral body surface (p < 0.001), and demonstration of foreign bodies (p = 0.033). CR and VR became more expressive with a higher grade of fracture dislocation (p < 0.001). 20% of all pathologies in the CR and VR reconstructions were not detectable by radiologists. CONCLUSION: CR reconstructions are superior to VR regarding the expressiveness. For fractures with substantial dislocation, soft tissue injuries, and foreign bodies in situ, CR showed a significantly better expressiveness than conventional PMCT. CR and VR have significant limitations in cases of fractures with minor dislocations and covered soft tissue injuries. ADVANCES IN KNOWLEDGE: CR is a helpful tool to present pathologies found in PMCT for judicial reviews.


Asunto(s)
Diagnóstico , Patologia Forense/métodos , Procesamiento de Imagen Asistido por Computador/métodos , Imagenología Tridimensional/métodos , Tomografía Computarizada por Rayos X/métodos , Heridas y Traumatismos/diagnóstico por imagen , Adulto , Anciano , Anciano de 80 o más Años , Femenino , Humanos , Masculino , Persona de Mediana Edad
3.
PLoS One ; 15(5): e0232403, 2020.
Artículo en Inglés | MEDLINE | ID: mdl-32374774

RESUMEN

We present novel multi-energy X-ray imaging methods for direct radiography and computed tomography. The goal is to determine the contribution of thickness, mass density and atomic composition to the measured X-ray absorption in the sample. Algorithms have been developed by our own to calculate new X-ray images using data from an unlimited amount of scans/images of different tube voltages by pixelwise fitting of the detected gray levels. The resulting images then show a contrast that is influenced either by the atomic number of the elements in the sample (photoelectric interactions) or by the mass density (Compton scattering). For better visualization, those images can be combined to a color image where different materials can easily be distinguished. In the case of computed tomography no established true multi-energy methodology that does not require an energy sensitive detector is known to the authors. The existing dual-energy methods often yield noisy results that need spatial averaging for clear interpretation. The goal of the method presented here is to qualitatively calculate atomic number and mass density images without loosing resolution while reducing the noise by the use of more than two X-ray energies. The resulting images are generated without the need of calibration stan-dards in an automatic and fast data processing routine. They provide additional information that might be of special interest in cases like archaeology where the destruction of a sample to determine its composition is no option, but a increase in measurement time is of little concern.


Asunto(s)
Radiografía/métodos , Tomografía Computarizada por Rayos X/métodos , Algoritmos , Simulación por Computador , Procesamiento de Imagen Asistido por Computador/métodos , Procesamiento de Imagen Asistido por Computador/estadística & datos numéricos , Imagenología Tridimensional/métodos , Imagenología Tridimensional/estadística & datos numéricos , Ciencia de los Materiales , Minerales/química , Radiografía/estadística & datos numéricos , Dispersión de Radiación , Tomografía Computarizada por Rayos X/estadística & datos numéricos , Rayos X
4.
Niger J Clin Pract ; 23(5): 596-602, 2020 May.
Artículo en Inglés | MEDLINE | ID: mdl-32367864

RESUMEN

Aim: The aim of this retrospective study is to evaluate and compare the 3-dimensional (3D) crown sizes of the left and right sides of upper and lower dental arches in patients with unilateral cleft lip and palate (UCLP). Materials and Methods: Dental casts of 94 patients all in permanent dentition were included in this study. Dental casts were divided into three groups as 36 casts with unilateral left cleft lip and palate (ULCLP), 18 casts with unilateral right cleft lip and palate (URCLP), and 40 casts without cleft (control). Mesiodistal (MD), buccolingual (BL), and gingiva incisal (GI) values of each tooth were measured by scanning the dental models with a high-precision optical 3D scanner. Paired t-test and independent t-test were used for statistical analysis. Results: U1 MD, U6 MD (P = 0.001) and BL (P = 0.01), L3 GI (P = 0.05) were greater in UCLP patients on the non-cleft side while U1 GI, L1 BL, L5 MD (P = 0.001), L4 MD, and BL (P = 0.01) values were found to be greater on the cleft side. Comparison of the cleft-sides and the control group showed that MD, BL, and GI dimensions of teeth on the cleft sides were generally found to be smaller, excluding the UR7 GI values for URCLP group (P = 0.05). Conclusion: In the measurements of teeth size, reliable and repeatable results were acquired through 3D software. Tooth size asymmetries can occur non-syndromic UCLP patients in both jaws. MD, BL, and GI dimensions of teeth are mostly found to be smaller in patients with CLP.


Asunto(s)
Labio Leporino , Imagenología Tridimensional/métodos , Odontometría/métodos , Corona del Diente/diagnóstico por imagen , Estudios de Casos y Controles , Niño , Fisura del Paladar/patología , Oclusión Dental , Femenino , Humanos , Procesamiento de Imagen Asistido por Computador/métodos , Masculino , Maxilar , Estudios Retrospectivos , Corona del Diente/patología
5.
PLoS One ; 15(5): e0233028, 2020.
Artículo en Inglés | MEDLINE | ID: mdl-32407341

RESUMEN

Computational studies can be used to support the development of peripheral nerve interfaces, but currently use simplified models of nerve anatomy, which may impact the applicability of simulation results. To better quantify and model neural anatomy across the population, we have developed an algorithm to automatically reconstruct accurate peripheral nerve models from histological cross-sections. We acquired serial median nerve cross-sections from human cadaveric samples, staining one set with hematoxylin and eosin (H&E) and the other using immunohistochemistry (IHC) with anti-neurofilament antibody. We developed a four-step processing pipeline involving registration, fascicle detection, segmentation, and reconstruction. We compared the output of each step to manual ground truths, and additionally compared the final models to commonly used extrusions, via intersection-over-union (IOU). Fascicle detection and segmentation required the use of a neural network and active contours in H&E-stained images, but only simple image processing methods for IHC-stained images. Reconstruction achieved an IOU of 0.42±0.07 for H&E and 0.37±0.16 for IHC images, with errors partially attributable to global misalignment at the registration step, rather than poor reconstruction. This work provides a quantitative baseline for fully automatic construction of peripheral nerve models. Our models provided fascicular shape and branching information that would be lost via extrusion.


Asunto(s)
Algoritmos , Procesamiento de Imagen Asistido por Computador/métodos , Imagenología Tridimensional/métodos , Nervios Periféricos/anatomía & histología , Cadáver , Humanos , Procesamiento de Imagen Asistido por Computador/estadística & datos numéricos , Imagenología Tridimensional/estadística & datos numéricos , Inmunohistoquímica , Modelos Anatómicos , Modelos Neurológicos , Prótesis Neurales , Coloración y Etiquetado
6.
Phys Rev Lett ; 124(19): 198104, 2020 May 15.
Artículo en Inglés | MEDLINE | ID: mdl-32469536

RESUMEN

The localization of point sources in optical microscopy enables nm-precision imaging of single-molecules and biological dynamics. We report a new method of localization microscopy using twin Airy beams that yields precise 3D localization with the key advantages of extended depth range, higher optical throughput, and potential for imaging higher emitter densities than are possible using other techniques. A precision of better than 30 nm was achieved over a depth range in excess of 7 µm using a 60×, 1.4 NA objective. An illustrative application to extended-depth-range blood-flow imaging in a live zebrafish is also demonstrated.


Asunto(s)
Imagenología Tridimensional/métodos , Microscopía/métodos , Animales , Cloaca/irrigación sanguínea , Imagenología Tridimensional/instrumentación , Microscopía/instrumentación , Imagen Molecular/instrumentación , Imagen Molecular/métodos , Flujo Sanguíneo Regional , Pez Cebra
7.
PLoS Biol ; 18(4): e3000678, 2020 04.
Artículo en Inglés | MEDLINE | ID: mdl-32243449

RESUMEN

Histological atlases of the cerebral cortex, such as those made famous by Brodmann and von Economo, are invaluable for understanding human brain microstructure and its relationship with functional organization in the brain. However, these existing atlases are limited to small numbers of manually annotated samples from a single cerebral hemisphere, measured from 2D histological sections. We present the first whole-brain quantitative 3D laminar atlas of the human cerebral cortex. It was derived from a 3D histological atlas of the human brain at 20-micrometer isotropic resolution (BigBrain), using a convolutional neural network to segment, automatically, the cortical layers in both hemispheres. Our approach overcomes many of the historical challenges with measurement of histological thickness in 2D, and the resultant laminar atlas provides an unprecedented level of precision and detail. We utilized this BigBrain cortical atlas to test whether previously reported thickness gradients, as measured by MRI in sensory and motor processing cortices, were present in a histological atlas of cortical thickness and which cortical layers were contributing to these gradients. Cortical thickness increased across sensory processing hierarchies, primarily driven by layers III, V, and VI. In contrast, motor-frontal cortices showed the opposite pattern, with decreases in total and pyramidal layer thickness from motor to frontal association cortices. These findings illustrate how this laminar atlas will provide a link between single-neuron morphology, mesoscale cortical layering, macroscopic cortical thickness, and, ultimately, functional neuroanatomy.


Asunto(s)
Corteza Cerebral/anatomía & histología , Corteza Cerebral/diagnóstico por imagen , Imagenología Tridimensional/métodos , Encéfalo/diagnóstico por imagen , Humanos , Imagen por Resonancia Magnética , Redes Neurales de la Computación
8.
PLoS One ; 15(4): e0221071, 2020.
Artículo en Inglés | MEDLINE | ID: mdl-32275668

RESUMEN

PURPOSE: To accelerate the acquisition of free-breathing 3D saturation-recovery-based (SASHA) myocardial T1 mapping by acquiring fewer saturation points in combination with a post-processing 3D denoising technique to maintain high accuracy and precision. METHODS: 3D SASHA T1 mapping acquires nine T1-weighted images along the saturation recovery curve, resulting in long acquisition times. In this work, we propose to accelerate conventional cardiac T1 mapping by reducing the number of saturation points. High T1 accuracy and low standard deviation (as a surrogate for precision) is maintained by applying a 3D denoising technique to the T1-weighted images prior to pixel-wise T1 fitting. The proposed approach was evaluated on a T1 phantom and 20 healthy subjects, by varying the number of T1-weighted images acquired between three and nine, both prospectively and retrospectively. Following the results from the healthy subjects, three patients with suspected cardiovascular disease were acquired using five T1-weighted images. T1 accuracy and precision was determined for all the acquisitions before and after denoising. RESULTS: In the T1 phantom, no statistical difference was found in terms of accuracy and precision for the different number of T1-weighted images before or after denoising (P = 0.99 and P = 0.99 for accuracy, P = 0.64 and P = 0.42 for precision, respectively). In vivo, both prospectively and retrospectively, the precision improved considerably with the number of T1-weighted images employed before denoising (P<0.05) but was independent on the number of T1-weighted images after denoising. CONCLUSION: We demonstrate the feasibility of accelerating 3D SASHA T1 mapping by reducing the number of acquired T1-weighted images in combination with an efficient 3D denoising, without affecting accuracy and precision of T1 values.


Asunto(s)
Enfermedades Cardiovasculares/diagnóstico por imagen , Corazón/diagnóstico por imagen , Imagenología Tridimensional/métodos , Imagen por Resonancia Magnética/métodos , Humanos , Imagenología Tridimensional/economía , Imagenología Tridimensional/instrumentación , Imagen por Resonancia Magnética/economía , Imagen por Resonancia Magnética/instrumentación , Fantasmas de Imagen , Estudios Retrospectivos
9.
PLoS One ; 15(4): e0232193, 2020.
Artículo en Inglés | MEDLINE | ID: mdl-32348334

RESUMEN

Insect wings are highly evolved structures with aerodynamic and structural properties that are not fully understood or systematically modeled. Most species in the insect order Odonata have permanently deployed high aspect ratio wings. Odonata have been documented to exhibit extraordinary flight performance and a wide range of interesting flight behaviors that rely on agility and efficiency. The characteristic three-dimensional corrugated structures of these wings have been observed and modeled for a small number of species, with studies showing that corrugations can provide significant aerodynamic and structural advantages. Comprehensive museum collections are the most practical source of Odonata wing, despite the risk of adverse effects caused by dehydration and preservation of specimens. Museum specimens are not to be handled or damaged and are best left undisturbed in their display enclosures. We have undertaken a systematic process of scanning, modeling, and post-processing the wings of over 80 Odonata species using a novel and accurate method and apparatus we developed for this purpose. The method allows the samples to stay inside their glass cases if necessary and is non-destructive. The measurements taken have been validated against micro-computed tomography scanning and against similar-sized objects with measured dimensions. The resulting publicly available dataset will allow aeronautical analysis of Odonata aerodynamics and structures, the study of the evolution of functional structures, and research into insect ecology. The technique is useable for other orders of insects and other fragile samples.


Asunto(s)
Odonata/anatomía & histología , Alas de Animales/anatomía & histología , Animales , Bases de Datos Factuales , Vuelo Animal/fisiología , Procesamiento de Imagen Asistido por Computador , Imagenología Tridimensional/instrumentación , Imagenología Tridimensional/métodos , Microscopía Electrónica de Rastreo , Modelos Anatómicos , Museos , Odonata/clasificación , Odonata/fisiología , Fotogrametría/instrumentación , Australia del Sur , Alas de Animales/fisiología , Alas de Animales/ultraestructura , Microtomografía por Rayos X
10.
J Laryngol Otol ; 134(4): 302-310, 2020 Apr.
Artículo en Inglés | MEDLINE | ID: mdl-32241307

RESUMEN

BACKGROUND: Recent developments in magnetic resonance imaging have enabled demonstration of endolymphatic hydrops, and the clinical application of these imaging studies in Ménière's disease is being explored. OBJECTIVE: To evaluate our centre's experience to date of hydrops magnetic resonance imaging in patients with episodic vertigo. METHODS: Magnetic resonance imaging was performed using a high-resolution three-dimensional fluid-attenuated inversion recovery sequence on a 3 Tesla scanner at 4 hours following double-dose gadolinium administration. RESULTS: The study included 31 patients, 28 of whom had a clinical diagnosis of Ménière's disease. In unilateral Ménière's disease, magnetic resonance imaging was able to lateralise endolymphatic hydrops to the clinically symptomatic ear in all cases. Mild hydrops was often seen in clinically asymptomatic ears. CONCLUSION: There is a good correlation between the clinical symptoms and lateralisation of hydropic changes on magnetic resonance imaging. Further refinements of imaging techniques and grading system will likely improve the diagnostic accuracy and clinical utilisation of hydrops magnetic resonance imaging.


Asunto(s)
Hidropesía Endolinfática/diagnóstico por imagen , Imagen por Resonancia Magnética/métodos , Enfermedad de Meniere/diagnóstico , Adulto , Anciano , Femenino , Gadolinio/administración & dosificación , Humanos , Imagenología Tridimensional/métodos , Masculino , Enfermedad de Meniere/clasificación , Enfermedad de Meniere/fisiopatología , Persona de Mediana Edad , Valor Predictivo de las Pruebas , Sensibilidad y Especificidad , Reino Unido/epidemiología , Vértigo/diagnóstico , Vértigo/epidemiología
11.
PLoS One ; 15(4): e0230415, 2020.
Artículo en Inglés | MEDLINE | ID: mdl-32271777

RESUMEN

Accurate segmentation of myocardial in cardiac MRI (magnetic resonance image) is key to effective rapid diagnosis and quantitative pathology analysis. However, a low-quality CMR (cardiac magnetic resonance) image with a large amount of noise makes it extremely difficult to accurately and quickly manually segment the myocardial. In this paper, we propose a method for CMR segmentation based on U-Net and combined with image sequence information. The method can effectively segment from the top slice to the bottom slice of the CMR. During training, each input slice depends on the slice below it. In other words, the predicted segmentation result depends on the existing segmentation label of the previous slice. 3D sequence information is fully utilized. Our method was validated on the ACDC dataset, which included CMR images of 100 patients (1700 2D MRI). Experimental results show that our method can segment the myocardial quickly and efficiently and is better than the current state-of-the-art methods. When evaluating 340 CMR image, our model yielded an average dice score of 85.02 ± 0.15, which is much higher than the existing classical segmentation method(Unet, Dice score = 0.78 ± 0.3).


Asunto(s)
Técnicas de Imagen Cardíaca/métodos , Aprendizaje Profundo , Corazón/diagnóstico por imagen , Procesamiento de Imagen Asistido por Computador/métodos , Imagen por Resonancia Magnética/métodos , Conjuntos de Datos como Asunto , Corazón/anatomía & histología , Ventrículos Cardíacos/anatomía & histología , Ventrículos Cardíacos/diagnóstico por imagen , Ventrículos Cardíacos/patología , Humanos , Imagenología Tridimensional/métodos , Miocardio/patología , Redes Neurales de la Computación
12.
PLoS One ; 15(4): e0232372, 2020.
Artículo en Inglés | MEDLINE | ID: mdl-32348366

RESUMEN

OBJECTIVES: Non-Cartesian Spiral readout can be implemented in 3D Time-of-flight (TOF) MR angiography (MRA) with short acquisition times. In this intra-individual comparison study we evaluated the clinical feasibility of Spiral TOF MRA in comparison with compressed sensing accelerated TOF MRA at 1.5T for intracranial vessel imaging as it has yet to be determined. MATERIALS AND METHODS: Forty-four consecutive patients with suspected intracranial vascular disease were imaged with two Spiral 3D TOFs (Spiral, 0.82x0.82x1.2 mm3, 01:32 min; Spiral 0.8, 0.8x0.8x0.8 mm3, 02:12 min) and a Compressed SENSE accelerated 3D TOF (CS 3.5, 0.82x0.82x1.2 mm3, 03:06 min) at 1.5T. Two neuroradiologists assessed qualitative (visualization of central and peripheral vessels) and quantitative image quality (Contrast Ratio, CR) and performed lesion and variation assessment for all three TOFs in each patient. After the rating process, the readers were questioned and representative cases were reinspected in a non-blinded fashion. For statistical analysis, the Friedman and Nemenyi post-hoc test, Kendall W tests, repeated measure ANOVA and weighted Cohen's Kappa tests were used. RESULTS: The Spiral and Spiral 0.8 outperformed the CS 3.5 in terms of peripheral image quality (p<0.001) and performed equally well in terms of central image quality (p>0.05). The readers noted slight differences in the appearance of maximum intensity projection images. A good to high degree of interstudy agreement between the three TOFs was observed for lesion and variation assessment (W = 0.638, p<0.001 -W = 1, p<0.001). CR values did not differ significantly between the three TOFs (p = 0.534). Interreader agreement ranged from good (K = 0.638) to excellent (K = 1). CONCLUSIONS: Compared to the CS 3.5, both the Spiral and Spiral 0.8 exhibited comparable or better image quality and comparable diagnostic performance at much shorter acquisition times.


Asunto(s)
Angiografía Cerebral/métodos , Trastornos Cerebrovasculares/diagnóstico por imagen , Angiografía por Resonancia Magnética/métodos , Adulto , Anciano , Anciano de 80 o más Años , Angiografía Cerebral/economía , Estudios de Factibilidad , Femenino , Humanos , Imagenología Tridimensional/economía , Imagenología Tridimensional/métodos , Angiografía por Resonancia Magnética/economía , Masculino , Persona de Mediana Edad , Factores de Tiempo
13.
PLoS One ; 15(4): e0232417, 2020.
Artículo en Inglés | MEDLINE | ID: mdl-32349123

RESUMEN

PURPOSE: Adolescent idiopathic scoliosis (AIS) is a three-dimensional spinal structural deformity that occurs in otherwise normal individuals. Although curve progression and severity vary amongst individuals, AIS can lead to significant cosmetic and functional deformity. AIS etiology has been determined to be genetic, however, exact genetic and biological processes underlying this disorder remain unknown. Vestibular structure and function have potentially been related to the etiopathogenesis of AIS. Here, we aimed to characterize the anatomy of the semicircular canals (SCC) within the vestibular system through a novel approach utilizing T2-weighted magnetic resonance images (MRI). METHODS: Three dimensional, MRI-based models of the SCCs were generated from AIS subjects (n = 20) and healthy control subjects (n = 19). Linear mixed models were used to compare SCC morphological measurements in the two groups. We compared side-to-side differences in the SCC measurements between groups (group*side interaction). RESULTS: Side-to-side differences in the lateral SCC were different between the two groups [false discovery rate adjusted p-value: 0.0107]. Orientation of right versus left lateral SCC was significantly different in the AIS group compared to the control group [mean side-to-side difference: -4.1°, 95% CI: -6.4° to -1.7°]. Overall, among subjects in the AIS group, the left lateral SCC tended to be oriented in a more horizontal position than subjects in the control group. SIGNIFICANCE: Asymmetry within the SCCs of the vestibular system of individuals with AIS potentially results in abnormal efferent activity to postural muscles. Consequences of this muscular activity during periods of rapid growth, which often coincides with AIS onset and progression, warrant consideration.


Asunto(s)
Escoliosis/patología , Canales Semicirculares/patología , Adolescente , Progresión de la Enfermedad , Femenino , Humanos , Imagenología Tridimensional/métodos , Imagen por Resonancia Magnética/métodos , Escoliosis/diagnóstico por imagen , Canales Semicirculares/diagnóstico por imagen
14.
Anesth Analg ; 130(5): 1244-1254, 2020 05.
Artículo en Inglés | MEDLINE | ID: mdl-32287131

RESUMEN

BACKGROUND: Cardiovascular waveforms contain information for clinical diagnosis. By learning and organizing the subtle change of waveform morphology from large amounts of raw waveform data, unsupervised manifold learning helps delineate a high-dimensional structure and display it as a novel 3-dimensional (3D) image. We hypothesize that the shape of this structure conveys clinically relevant inner dynamics information. METHODS: To validate this hypothesis, we investigate the electrocardiography (ECG) waveform for ischemic heart disease and arterial blood pressure (ABP) waveform in dynamic vasoactive episodes. We model each beat or pulse to be a point lying on a manifold-like a surface-and use the diffusion map (DMap) to establish the relationship among those pulses. The output of the DMap is converted to a 3D image for visualization. For ECG datasets, first we analyzed the non-ST-elevation ECG waveform distribution from unstable angina to healthy control in the 3D image, and we investigated intraoperative ST-elevation ECG waveforms to show the dynamic ECG waveform changes. For ABP datasets, we analyzed waveforms collected under endotracheal intubation and administration of vasodilator. To quantify the dynamic separation, we applied the support vector machine (SVM) analysis and reported the total accuracy and macro-F1 score. We further performed the trajectory analysis and derived the moving direction of successive beats (or pulses) as vectors in the high-dimensional space. RESULTS: For the non-ST-elevation ECG, a hierarchical tree structure comprising consecutive ECG waveforms spanning from unstable angina to healthy control is presented in the 3D image (accuracy = 97.6%, macro-F1 = 96.1%). The DMap helps quantify and visualize the evolving direction of intraoperative ST-elevation myocardial episode in a 1-hour period (accuracy = 97.58%, macro-F1 = 96.06%). The ABP waveform analysis of Nicardipine administration shows interindividual difference (accuracy = 95.01%, macro-F1 = 96.9%) and their common directions from intraindividual moving trajectories. The dynamic change of the ABP waveform during endotracheal intubation shows a loop-like trajectory structure, which can be further divided using the manifold learning knowledge obtained from Nicardipine. CONCLUSIONS: The DMap and the generated 3D image of ECG or ABP waveforms provides clinically relevant inner dynamics information. It provides clues of acute coronary syndrome diagnosis, shows clinical course in myocardial ischemic episode, and reveals underneath physiological mechanism under stress or vasodilators.


Asunto(s)
Bases de Datos Factuales , Electrocardiografía/métodos , Frecuencia Cardíaca/fisiología , Imagenología Tridimensional/métodos , Aprendizaje Automático no Supervisado , Análisis de Ondículas , Humanos , Procesamiento de Señales Asistido por Computador
15.
Niger J Clin Pract ; 23(4): 456-463, 2020 Apr.
Artículo en Inglés | MEDLINE | ID: mdl-32246650

RESUMEN

Aims: The purpose of this study was to observe the stresses of all-on-four implant designs in an edentulous mandible in the implant, surrounding bone, and monolithic ceramics. Materials and Methods: In mandibular all-on-four implant models, anterior implants were placed vertically, and posterior implants were differently inclined. On the full-arch fixed prosthetic restoration monolithic zirconia framework, monolithic lithium disilicate was prepared as the superstructure. Model 1M (1M-15.5); posterior implants angled at 15° to the occlusion plane and a cantilever length of 5 mm, Model 2M; (2M-15.9), Model 3M; (3M-30.5), and Model 4M; (4M-30.9) were prepared. A total of 300 N bilateral force was applied at an angle of 30° and oblique to the occlusion plane. Stress values on dental implants, abutments, the surrounding bone, and prosthetic restorations were calculated. Results: The highest stress concentration was observed in the 2nd connector region between the canine and the 1st premolar tooth in the monolithic zirconia frameworks (457.21 MPa). Stress concentration in the cortical bone was 60.93 MPa in posterior implants. Stress was higher in posterior angled implants than straight implants. Stress at posterior angulation increased by 21 MPa in implants angled at 15°. Conclusion: In bilateral loading, the force applied to anterior implants does not have a significant effect on the bone structure. Stress concentration increases in posterior angled implants and surrounding bone. Moreover, stress concentration increases as the length of the cantilever, the weakest part in all-on-four implants, increases. As posterior implant angulation increases, stress concentration level and localization are affected.


Asunto(s)
Cerámica/química , Implantes Dentales , Prótesis Dental de Soporte Implantado/métodos , Imagenología Tridimensional/métodos , Titanio/química , Circonio/química , Diente Premolar , Arco Dental/fisiología , Modelos Dentales , Diseño de Prótesis Dental , Análisis del Estrés Dental , Análisis de Elementos Finitos , Humanos , Mandíbula/fisiología , Estrés Mecánico
16.
PLoS Comput Biol ; 16(4): e1007756, 2020 04.
Artículo en Inglés | MEDLINE | ID: mdl-32251448

RESUMEN

Recent advances in electron microscopy have enabled the imaging of single cells in 3D at nanometer length scale resolutions. An uncharted frontier for in silico biology is the ability to simulate cellular processes using these observed geometries. Enabling such simulations requires watertight meshing of electron micrograph images into 3D volume meshes, which can then form the basis of computer simulations of such processes using numerical techniques such as the finite element method. In this paper, we describe the use of our recently rewritten mesh processing software, GAMer 2, to bridge the gap between poorly conditioned meshes generated from segmented micrographs and boundary marked tetrahedral meshes which are compatible with simulation. We demonstrate the application of a workflow using GAMer 2 to a series of electron micrographs of neuronal dendrite morphology explored at three different length scales and show that the resulting meshes are suitable for finite element simulations. This work is an important step towards making physical simulations of biological processes in realistic geometries routine. Innovations in algorithms to reconstruct and simulate cellular length scale phenomena based on emerging structural data will enable realistic physical models and advance discovery at the interface of geometry and cellular processes. We posit that a new frontier at the intersection of computational technologies and single cell biology is now open.


Asunto(s)
Procesamiento de Imagen Asistido por Computador/métodos , Imagenología Tridimensional/métodos , Algoritmos , Simulación por Computador , Dendritas/fisiología , Difusión , Análisis de Elementos Finitos , Humanos , Modelos Biológicos , Modelos Teóricos , Programas Informáticos , Mallas Quirúrgicas
17.
PLoS Comput Biol ; 16(4): e1007449, 2020 04.
Artículo en Inglés | MEDLINE | ID: mdl-32240155

RESUMEN

The purpose of this quick guide is to help new modelers who have little or no background in comparative modeling yet are keen to produce high-resolution protein 3D structures for their study by following systematic good modeling practices, using affordable personal computers or online computational resources. Through the available experimental 3D-structure repositories, the modeler should be able to access and use the atomic coordinates for building homology models. We also aim to provide the modeler with a rationale behind making a simple list of atomic coordinates suitable for computational analysis abiding to principles of physics (e.g., molecular mechanics). Keeping that objective in mind, these quick tips cover the process of homology modeling and some postmodeling computations such as molecular docking and molecular dynamics (MD). A brief section was left for modeling nonprotein molecules, and a short case study of homology modeling is discussed.


Asunto(s)
Biología Computacional/métodos , Imagenología Tridimensional/métodos , Algoritmos , Aminoácidos/química , Simulación por Computador , Bases de Datos de Proteínas , Concentración de Iones de Hidrógeno , Internet , Iones , Ligandos , Aprendizaje Automático , Modelos Biológicos , Simulación del Acoplamiento Molecular , Simulación de Dinámica Molecular , Pliegue de Proteína , Procesamiento Proteico-Postraduccional , Proteínas/química , Programas Informáticos , Solventes , Homología Estructural de Proteína , Agua
18.
PLoS One ; 15(4): e0230754, 2020.
Artículo en Inglés | MEDLINE | ID: mdl-32302315

RESUMEN

Normal brain segmentation is available via FreeSurfer, Vbm, and Ibaspm software. However, these software packages cannot perform segmentation of the brain for patients with brain tumors. As we know, damage from extracerebral tumors to the brain occurs mainly by way of pushing and compressing while leaving the structure of the brain intact. Three-dimensional (3D) imaging, augmented reality (AR), and virtual reality (VR) technology have begun to be applied in clinical practice. The free medical open-source software 3D Slicer allows us to perform 3D simulations on a computer and requires little user interaction. Moreover, 3D Slicer can integrate with the third-party software mentioned above. The relationship between the tumor and surrounding brain tissue can be judged, but accurate brain segmentation cannot be performed using 3D Slicer. In this study, we combine 3D Slicer and FreeSurfer to provide a novel brain segmentation method for extracerebral tumors. This method can help surgeons identify the "real" relationship between the lesion and adjacent brain tissue before surgery and improve preoperative planning.


Asunto(s)
Neoplasias Encefálicas/patología , Encéfalo/patología , Adolescente , Adulto , Anciano , Computadores , Femenino , Humanos , Procesamiento de Imagen Asistido por Computador/métodos , Imagenología Tridimensional/métodos , Masculino , Persona de Mediana Edad , Programas Informáticos , Interfaz Usuario-Computador , Realidad Virtual , Adulto Joven
19.
PLoS Comput Biol ; 16(3): e1007747, 2020 03.
Artículo en Inglés | MEDLINE | ID: mdl-32231351

RESUMEN

Protein structure determines biological function. Accurately conceptualizing 3D protein/ligand structures is thus vital to scientific research and education. Virtual reality (VR) enables protein visualization in stereoscopic 3D, but many VR molecular-visualization programs are expensive and challenging to use; work only on specific VR headsets; rely on complicated model-preparation software; and/or require the user to install separate programs or plugins. Here we introduce ProteinVR, a web-based application that works on various VR setups and operating systems. ProteinVR displays molecular structures within 3D environments that give useful biological context and allow users to situate themselves in 3D space. Our web-based implementation is ideal for hypothesis generation and education in research and large-classroom settings. We release ProteinVR under the open-source BSD-3-Clause license. A copy of the program is available free of charge from http://durrantlab.com/protein-vr/, and a working version can be accessed at http://durrantlab.com/pvr/.


Asunto(s)
Biología Computacional/métodos , Imagenología Tridimensional/métodos , Internet , Proteínas , Realidad Virtual , Conformación Proteica , Proteínas/química , Proteínas/ultraestructura
20.
Eur J Vasc Endovasc Surg ; 60(1): 135-143, 2020 Jul.
Artículo en Inglés | MEDLINE | ID: mdl-32312666

RESUMEN

OBJECTIVE: Fiber Optic RealShape (FORS) is a new technology platform that enables real time three dimensional (3D) visualisation of endovascular guidewires and catheters, based on the concepts of fibre optic technology instead of fluoroscopy. Anatomical context is provided by means of co-registered prior anatomical imaging, such as digital subtraction angiography or computed tomography. This preclinical study assesses the safety and feasibility of FORS technology. METHODS: Six physicians performed endovascular tasks in a phantom model and a porcine model using FORS enabled floppy guidewires, Cobra-2 catheters and Berenstein catheters. Each physician performed a set of predefined tasks in both models, including setup of the FORS system, device registration, and 12 aortic and peripheral target vessel cannulation tasks. The evaluation of the FORS system was based on (i) target vessel cannulation success; (ii) safety assessment; (iii) the accuracy of the FORS based device visualisation; and (iv) user experience. RESULTS: Successful cannulation was achieved in 72 of the 72 tasks (100%) in the phantom model and in 70 of the 72 tasks (97%) in the porcine model. No safety issues were reported. The FORS based device visualisation had a median offset at the tip of 2.2 mm (interquartile range 1.2-3.8 mm). The users judged the FORS based device visualisation to be superior to conventional fluoroscopic imaging, while not affecting the mechanical properties (torquability, pushability) of the FORS enabled guidewire and catheters. CONCLUSION: The combined outcomes of high cannulation success, positive user experience, adequate accuracy, and absence of safety issues demonstrate the safety and feasibility of the FORS system in a preclinical environment. FORS technology has great potential to improve device visualisation in endovascular interventions.


Asunto(s)
Procedimientos Endovasculares/instrumentación , Tecnología de Fibra Óptica , Imagenología Tridimensional/instrumentación , Dispositivos de Acceso Vascular , Animales , Vasos Sanguíneos/diagnóstico por imagen , Vasos Sanguíneos/patología , Cateterismo Periférico/instrumentación , Cateterismo Periférico/métodos , Procedimientos Endovasculares/métodos , Femenino , Tecnología de Fibra Óptica/métodos , Humanos , Imagenología Tridimensional/métodos , Porcinos
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