Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 1.874
Filtrar
1.
PLoS One ; 15(9): e0238783, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32946473

RESUMO

Diffusible iodine-based contrast-enhanced computed tomography (diceCT) techniques allow visualization of soft tissues of fluid-preserved specimens in three dimensions without dissection or histology. Two popular diceCT stains, iodine-potassium iodide (I2KI) dissolved in water and elemental iodine (I2) dissolved in 100% ethanol (EtOH), yield striking results. Despite the widespread use of these stains in clinical and biological fields, the molecular mechanisms that result in color change and radiopacity attributed to iodine staining are poorly understood. Requests to apply these stains to anatomical specimens preserved in natural history museums are increasing, yet curators have little information about the potential for degradation of treated specimens. To assess the molecular effects of iodine staining on typical museum specimens, we compared the two popular stains and two relatively unexplored stains (I2KI in 70% EtOH, I2 in 70% EtOH). House sparrows (Passer domesticus) were collected and preserved under uniform conditions following standard museum protocols, and each was then subjected to one of the stains. Results show that the three ethanol-based stains worked equally well (producing fully stained, life-like, publication quality scans) but in different timeframes (five, six, or eight weeks). The specimen in I2KI in water became degraded in physical condition, including developing flexible, demineralized bones. The ethanol-based methods also resulted in some demineralization but less than the water-based stain. The pH of the water-based stain was notably acidic compared to the water used as solvent in the stain. Our molecular analyses indicate that whereas none of the stains resulted in unacceptable levels of protein degradation, the bones of a specimen stained with I2KI in water demineralized throughout the staining process. We conclude that staining with I2KI or elemental I2 in 70% EtOH can yield high-quality soft-tissue visualization in a timeframe that is similar to that of better-known iodine-based stains, with lower risk of negative impacts on specimen condition.


Assuntos
Preservação Biológica/métodos , Coloração e Rotulagem , Microtomografia por Raio-X/métodos , Animais , Aves/anatomia & histologia , Meios de Contraste/química , Iodo/química , Museus
2.
Nat Commun ; 11(1): 4686, 2020 09 17.
Artigo em Inglês | MEDLINE | ID: mdl-32943633

RESUMO

Electrophysiology provides a direct readout of neuronal activity at a temporal precision only limited by the sampling rate. However, interrogating deep brain structures, implanting multiple targets or aiming at unusual angles still poses significant challenges for operators, and errors are only discovered by post-hoc histological reconstruction. Here, we propose a method combining the high-resolution information about bone landmarks provided by micro-CT scanning with the soft tissue contrast of the MRI, which allowed us to precisely localize electrodes and optic fibers in mice in vivo. This enables arbitrating the success of implantation directly after surgery with a precision comparable to gold standard histology. Adjustment of the recording depth with micro-drives or early termination of unsuccessful experiments saves many working hours, and fast 3-dimensional feedback helps surgeons avoid systematic errors. Increased aiming precision enables more precise targeting of small or deep brain nuclei and multiple targeting of specific cortical or hippocampal layers.


Assuntos
Encéfalo/diagnóstico por imagem , Eletrodos Implantados , Processamento de Imagem Assistida por Computador/métodos , Fibras Ópticas , Microtomografia por Raio-X/métodos , Animais , Comportamento Animal , Encéfalo/patologia , Mapeamento Encefálico , Hipocampo/diagnóstico por imagem , Hipocampo/patologia , Hipocampo/cirurgia , Técnicas Histológicas/métodos , Imagem por Ressonância Magnética/métodos , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Modelos Animais , Silício , Técnicas Estereotáxicas
3.
PLoS One ; 15(8): e0237042, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32813735

RESUMO

The largest dinosaurs were enormous animals whose body mass placed massive gravitational loads on their skeleton. Previous studies investigated dinosaurian bone strength and biomechanics, but the relationships between dinosaurian trabecular bone architecture and mechanical behavior has not been studied. In this study, trabecular bone samples from the distal femur and proximal tibia of dinosaurs ranging in body mass from 23-8,000 kg were investigated. The trabecular architecture was quantified from micro-computed tomography scans and allometric scaling relationships were used to determine how the trabecular bone architectural indices changed with body mass. Trabecular bone mechanical behavior was investigated by finite element modeling. It was found that dinosaurian trabecular bone volume fraction is positively correlated with body mass similar to what is observed for extant mammalian species, while trabecular spacing, number, and connectivity density in dinosaurs is negatively correlated with body mass, exhibiting opposite behavior from extant mammals. Furthermore, it was found that trabecular bone apparent modulus is positively correlated with body mass in dinosaurian species, while no correlation was observed for mammalian species. Additionally, trabecular bone tensile and compressive principal strains were not correlated with body mass in mammalian or dinosaurian species. Trabecular bone apparent modulus was positively correlated with trabecular spacing in mammals and positively correlated with connectivity density in dinosaurs, but these differential architectural effects on trabecular bone apparent modulus limit average trabecular bone tissue strains to below 3,000 microstrain for estimated high levels of physiological loading in both mammals and dinosaurs.


Assuntos
Osso Esponjoso/anatomia & histologia , Osso Esponjoso/fisiologia , Dinossauros/anatomia & histologia , Animais , Anisotropia , Fenômenos Biomecânicos , Densidade Óssea/fisiologia , Osso e Ossos/anatomia & histologia , Força Compressiva/fisiologia , Simulação por Computador , Fêmur/anatomia & histologia , Análise de Elementos Finitos , Fósseis , Processamento de Imagem Assistida por Computador/métodos , Mamíferos/anatomia & histologia , Estresse Mecânico , Tíbia/anatomia & histologia , Microtomografia por Raio-X/métodos
4.
J Cancer Res Ther ; 16(3): 612-618, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32719276

RESUMO

Objective: The objective of this study is to evaluate the effects of radiotherapy doses on mineral density and percentage mineral volume of human permanent tooth enamel. Materials and Methods: Synchrotron radiation Xray microcomputed tomography (SRµCT) and microhardness testing were carried out on 8 and 20 tooth samples, respectively. Enamel mineral density was derived from SRµCT technique using ImageJ software. Microhardness samples were subjected to Vickers indentations followed by calculation of microhardness and percentage mineral volume values using respective mathematical measures. Data were analyzed using paired t-test at a significance level of 5%. Qualitative analysis of the enamel microstructure was done with two-dimensional projection images and scanned electron micrographs using µCT and field emission scanning electron microscopy, respectively. Results: Vickers microhardness and SRµCT techniques showed a decrease in microhardness and an increase in mineral density, respectively, in postirradiated samples. These changes were related to mineral density variation and alteration of hydroxyapatite crystal lattice in enamel surface. Enamel microstructure showed key features such as microporosities and loss of smooth homogeneous surface. These indicate tribological loss and delamination of enamel which might lead to radiation caries. Conclusions: Tooth surface loss might be a major contributing factor for radiation caries in head-and-neck cancer patients prescribed to radiotherapy. Such direct effects of radiotherapy cause enamel abrasion, delamination, and damage to the dentinoenamel junction. Suitable measures should, therefore, be worked out to protect nontarget oral tissues such as teeth while delivering effective dosages to target regions.


Assuntos
Esmalte Dentário/efeitos da radiação , Neoplasias de Cabeça e Pescoço/radioterapia , Lesões por Radiação/etiologia , Desmineralização do Dente/etiologia , Esmalte Dentário/ultraestrutura , Dureza/efeitos da radiação , Neoplasias de Cabeça e Pescoço/patologia , Humanos , Técnicas In Vitro , Microscopia Eletrônica de Varredura/métodos , Lesões por Radiação/patologia , Propriedades de Superfície , Desmineralização do Dente/patologia , Microtomografia por Raio-X/métodos
5.
J Vis Exp ; (160)2020 06 20.
Artigo em Inglês | MEDLINE | ID: mdl-32628170

RESUMO

Blood vessels form intricate networks in 3-dimensional space. Consequently, it is difficult to visually appreciate how vascular networks interact and behave by observing the surface of a tissue. This method provides a means to visualize the complex 3-dimensional vascular architecture of the lung. To accomplish this, a catheter is inserted into the pulmonary artery and the vasculature is simultaneously flushed of blood and chemically dilated to limit resistance. Lungs are then inflated through the trachea at a standard pressure and the polymer compound is infused into the vascular bed at a standard flow rate. Once the entire arterial network is filled and allowed to cure, the lung vasculature may be visualized directly or imaged on a micro-CT (µCT) scanner. When performed successfully, one can appreciate the pulmonary arterial network in mice ranging from early postnatal ages to adults. Additionally, while demonstrated in the pulmonary arterial bed, this method can be applied to any vascular bed with optimized catheter placement and endpoints.


Assuntos
Pulmão/irrigação sanguínea , Pulmão/diagnóstico por imagem , Microcirculação , Artéria Pulmonar/diagnóstico por imagem , Microtomografia por Raio-X/métodos , Animais , Animais Recém-Nascidos , Camundongos , Camundongos Endogâmicos C57BL
6.
Chemosphere ; 260: 127562, 2020 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-32683025

RESUMO

The presence of organic immiscible liquids such as chlorinated solvents and fuels continues to be a primary source of risk for many hazardous waste sites. In this study, the standard miscible-displacement interfacial partitioning tracer test (IPTT) method was used for the first time to measure NAPL-water interfacial areas for a range of saturations. Multiple measurements were conducted for a natural quartz sand, with tetrachloroethene as the representative NAPL. The interfacial areas increased with decreasing water saturation. The measurements compared well to interfacial areas measured for the same sand with two alternative tracer methods, the mass-distribution batch method and the two-phase flow method. Measurements obtained with all three tracer-based methods exhibit a relatively large degree of variability. Thus, it is important to employ replication when using these methods. In contrast, interfacial areas measured with x-ray microtomography exhibit very small variability. However, the measured interfacial areas do not capture the contribution of surface-roughness to film-associated interfacial area. Each method has associated advantages and disadvantages, and it is important to be cognizant of them during their application.


Assuntos
Movimentos da Água , Água/química , Resíduos Perigosos , Fenômenos Físicos , Porosidade , Quartzo/química , Propriedades de Superfície , Tetracloroetileno/química , Microtomografia por Raio-X/métodos
7.
Acta Odontol Latinoam ; 33(1): 33-37, 2020 Apr 01.
Artigo em Inglês | MEDLINE | ID: mdl-32621597

RESUMO

This study evaluated the internal morphology of lower incisors using computerized microtomography (micro-CT) images. Eighty-nine lower incisors were scanned by micro-CT and reconstructed with NRecon software. 2D parameters (perimeter, root length, circularity and canal diameter) and 3D parameters (volume, surface area and structure model index) were evaluated with CTAn and CTVol software. The results are presented descriptively. It was found that 89.9% of the canals had a single main root canal (type I), followed by type II (6.7%) and III (3.4%), while 5.6% of the specimens presented lateral canals and 1.1% had an apical delta. Mean volume and surface area were 31.80mm³ and 90.58mm², respectively. The most prevalent shape of the root canal at CEJ level was circular (41.6%) and 1mm from the apex, 73% of the samples were classified as oval. Lower incisors with internal anatomical variations may offer a high degree of technical complexity and may result in treatment failure.


Assuntos
Cavidade Pulpar/diagnóstico por imagem , Incisivo/anatomia & histologia , Mandíbula , Microtomografia por Raio-X/métodos , Humanos , Processamento de Imagem Assistida por Computador , Incisivo/diagnóstico por imagem
8.
Rev. cuba. estomatol ; 57(2): e2901, abr.-jun. 2020. tab, graf
Artigo em Português | LILACS, CUMED | ID: biblio-1126500

RESUMO

RESUMO Introdução: Os estudos científicos acerca das propriedades físicas e mecânicas apresentadas pelas resinas compostas são cada vez mais necessários diante da grande variedade de produtos disponíveis no mercado atual, resultante do aumento de sua demanda dentro da odontologia que preza por preparos minimamente invasivos com a devolução das características estéticas e funcionais do elemento dentário. Objetivo: Avaliar e comparar a microdureza e porosidade das resinas compostas fotopolimerizavéis Filtek Z350 XT 3M e Zirconfill Technew. Métodos: Foram confeccionados 10 corpos de prova por amostra (n= 10) submetidos a teste microdureza Vickers e porosidade por microtomografia computadorizada. Resultados: Com relação à presença de porosidades, dada em porcentagem, o grupo da Filtek apresentou os menores valores médios. Quando comparado estatisticamente, os grupos apresentaram diferença estatística (p= 0,019), com uma magnitude de efeito alta. Com relação aos valores de microdureza, o grupo da Filtek apresentou os maiores valores médios. Quando comparados estatisticamente, os grupos não apresentaram diferença estatística (p > 0,05). Conclusões: A porosidade foi significativamente diferente entre os grupos estudados, sendo o grupo Filtek Z350XT de menor percentual. No entanto, os grupos não apresentaram diferença estatística para microdureza, apesar do grupo Filtek Z350XT ter apresentado maior valor médio(AU)


RESUMEN Introducción: Los estudios científicos sobre las propiedades físicas y mecánicas presentadas por las resinas compuestas son cada vez más necesarios ante la gran variedad de productos disponibles en el mercado actual, resultante del aumento de su demanda dentro de la odontología que aprecia por preparaciones mínimamente invasivas con la devolución de las características estéticas y funcionales del elemento dental. Objetivo: Evaluar y comparar la microdureza y porosidad de las resinas compuestas fotopolimerizables Filtek Z350 XT 3M y Zirconfill Technew. Métodos: Se han confeccionado 10 cuerpos de prueba por muestra (n= 10) sometidos a prueba de microdureza Vickers y porosidad por microtomografía computarizada. Resultados: Con respecto a la presencia de porosidades, dada en porcentaje, el grupo de Filtek presentó los menores valores medios. Cuando se comparó estadísticamente, los grupos presentaron una diferencia estadística (p= 0,019), con una magnitud de efecto alto. Con respecto a los valores de microdureza, el grupo de Filtek presentó los mayores valores medios. Cuando se comparó estadísticamente, los grupos no presentaron una diferencia estadística (p> 0,05). Conclusiones: La porosidad fue significativamente diferente entre los grupos estudiados, siendo el grupo Filtek Z350XT de menor porcentaje. Sin embargo, los grupos no presentaron diferencia estadística para microdureza, a pesar de que el grupo Filtek Z350XT presentó un valor medio más alto(AU)


ABSTRACT Introduction: Scientific studies about the physical and mechanical properties of composite resins are increasingly needed in view of the wide variety of products available in the market today, resulting from the increase in their demand for dental care purposes, with a preference for minimally invasive preparations aimed at restoring the esthetic and functional characteristics of the treated element. Objective: Evaluate and compare the microhardness and porosity of the photopolymerizable composite resins Filtek Z350 XT and Zirconfill Technew. Methods: Ten test bodies were developed per sample (n= 10) and subjected to Vickers microhardness and porosity testing by computerized microtomography. Results: With respect to the presence of porosity, expressed in percentages, the Filtek group had the lowest mean values. When compared statistically, the two groups showed a statistical difference (p= 0.019) with a high effect magnitude. Regarding microhardness, the Filtek group had the highest mean values. Statistical comparison did not find any difference between the groups (p> 0.05). Conclusions: Porosity was significantly different in the groups studied, the Filtek Z350XT group exhibiting the lowest percentage. However, the groups did not show any statistical difference concerning microhardness, despite the fact that the Filtek Z350XT group had a higher mean value(AU)


Assuntos
Humanos , Assistência Odontológica/efeitos adversos , Resinas Compostas/efeitos adversos , Microtomografia por Raio-X/métodos , Testes de Dureza/métodos , Propriedades Físicas
9.
Braz Oral Res ; 34: e056, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32578799

RESUMO

This study presents an overview of the accuracy of cone beam computed tomography (CBCT) compared with micro-computed tomography (µCT) in the assessment of root canal morphology of extracted human permanent teeth. A database search in PubMed, PubMed Central, Embase, Scopus, Opengrey, Scielo and Virtual Health Library was conducted which compared root canal morphology of extracted human permanent teeth on the accuracy of CBCT with µCT. In accordance with PRISMA statement guidelines, data were extracted on study characteristics, target mediators, sampling and assay techniques and the parameters associated with obtaining the image and ability to identify the root canal morphology. Amongst 2734 records, ten fulfilled the inclusion criteria. Four studies compared the accuracy of CBCT and µCT in the assessment of root canal morphology using Vertucci's classification, with at least one CBCT group or subgroup of each study presented high agreement compared to the µCT. Six studies assessed more detailed root canal morphology, including two articles that found a lack of agreement between these imaging systems. Risk of bias was deemed low in three studies, moderate in four and high in three. CBCT can be as accurate as µCT in the assessment of several morphological features of extracted human permanent teeth; however there are some exceptions related to the more detailed morphological aspects. Voxel size likely influences the ability to detect these features, though the different aspects of exposure setting used in studies components may be confounding factors. CBCT may be considered for the assessment of root canal morphology ex-vivo.


Assuntos
Tomografia Computadorizada de Feixe Cônico/métodos , Cavidade Pulpar/anatomia & histologia , Cavidade Pulpar/diagnóstico por imagem , Microtomografia por Raio-X/métodos , Humanos , Valores de Referência , Fatores de Risco
10.
Braz Oral Res ; 34: e039, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32374813

RESUMO

To compare the shaping ability of different single-file systems in the preparation of mesial curved canals of mandibular molars using micro-CT technology. Fifteen mesial roots of mandibular molars with two independent and curved canals (n = 30) were selected, scanned at a resolution of 26.7 µm anatomically matched, and distributed into three groups (n = 10), according to the preparation system: WaveOne 25.08, Reciproc 25.08, and OneShape 25.06. A final micro-CT scanning was performed, data sets were registered with their respective counterparts, and compared regarding the three-dimensional (volume, surface area, and structure model index - SMI) and two-dimensional (perimeter, area, roundness, major and minor diameters) parameters, as well as, canal transportation, using ANOVA and post hoc Tukey tests (α = 5%). Overall, no difference was observed between groups regarding area, perimeter, volume, surface area, and canal transportation (p > 0.05). Within group, no canal transportation was significantly higherobserved in the apical third (0.10 ± 0.05 mm) compared to coronal (0.08±0.040 mm) and middle (0.07 ± 0.03 mm) thirds (p < 0.05). Structure model index (SMI) was statistically higher after preparation with OneShape instrument (0.36 ± 0.26) compared to other systems (p < 0.05). Within the parameters of this study, similar shaping ability was observed in the preparation of mesial curved root canals of mandibular molars with Reciproc, OneShape and WaveOne systems.


Assuntos
Cavidade Pulpar/anatomia & histologia , Cavidade Pulpar/diagnóstico por imagem , Preparo de Canal Radicular/instrumentação , Análise de Variância , Instrumentos Odontológicos , Desenho de Equipamento , Humanos , Teste de Materiais , Dente Molar/anatomia & histologia , Valores de Referência , Estatísticas não Paramétricas , Microtomografia por Raio-X/métodos
11.
Am J Obstet Gynecol ; 223(4): 493-515, 2020 10.
Artigo em Inglês | MEDLINE | ID: mdl-32376319

RESUMO

Fetal death because of miscarriage, unexpected intrauterine fetal demise, or termination of pregnancy is a traumatic event for any family. Despite advances in prenatal imaging and genetic diagnosis, conventional autopsy remains the gold standard because it can provide additional information not available during fetal life in up to 40% of cases and this by itself may change the recurrence risk and hence future counseling for parents. However, conventional autopsy is negatively affected by procedures involving long reporting times because the fetal brain is prone to the effect of autolysis, which may result in suboptimal examinations, particularly of the central nervous system. More importantly, fewer than 50%-60% of parents consent to invasive autopsy, mainly owing to the concerns about body disfigurement. Consequently, this has led to the development of noninvasive perinatal virtual autopsy using imaging techniques. Because a significant component of conventional autopsy involves the anatomic examination of organs, imaging techniques such as magnetic resonance imaging, ultrasound, and computed tomography are possible alternatives. With a parental acceptance rate of nearly 100%, imaging techniques as part of postmortem examination have become widely used in recent years in some countries. Postmortem magnetic resonance imaging using 1.5-Tesla magnets is the most studied technique and offers an overall diagnostic accuracy of 77%-94%. It is probably the best choice as a virtual autopsy technique for fetuses >20 weeks' gestation. However, for fetuses <20 weeks' gestation, its performance is poor. The use of higher magnetic resonance imaging magnetic fields such as 3-Tesla may slightly improve performance. Of note, in cases of fetal maceration, magnetic resonance imaging may offer diagnoses in a proportion of brain lesions wherein conventional autopsy fails. Postmortem ultrasound examination using a high-frequency probe offers overall sensitivity and specificity of 67%-77% and 74%-90%, respectively, with the advantage of easy access and affordability. The main difference between postmortem ultrasound and magnetic resonance imaging relates to their respective abilities to obtain images of sufficient quality for a confident diagnosis. The nondiagnostic rate using postmortem ultrasound ranges from 17% to 30%, depending on the organ examined, whereas the nondiagnostic rate using postmortem magnetic resonance imaging in most situations is far less than 10%. For fetuses ≤20 weeks' gestation, microfocus computed tomography achieves close to 100% agreement with autopsy and is likely to be the technique of the future in this subgroup. The lack of histology has always been listed as 1 limitation of all postmortem imaging techniques. Image-guided needle tissue biopsy coupled with any postmortem imaging can overcome this limitation. In addition to describing the diagnostic accuracy and limitations of each imaging technology, we propose a novel, stepwise diagnostic approach and describe the possible application of these techniques in clinical practice as an alternative or an adjunct or for triage to select cases that would specifically benefit from invasive examination, with the aim of reducing parental distress and pathologist workload. The widespread use of postmortem fetal imaging is inevitable, meaning that hurdles such as specialized training and dedicated financing must be overcome to improve access to these newer, well-validated techniques.


Assuntos
Autopsia , Anormalidades Congênitas/diagnóstico por imagem , Feto/diagnóstico por imagem , Idade Gestacional , Imagem por Ressonância Magnética/métodos , Ultrassonografia/métodos , Microtomografia por Raio-X/métodos , Biópsia , Morte Fetal , Humanos , Pais , Preferência do Paciente , Natimorto
12.
Int. j. morphol ; 38(2): 477-480, abr. 2020. tab, graf
Artigo em Inglês | LILACS | ID: biblio-1056465

RESUMO

This study aimed to examine the differences in bone microarchitecture between different regions of the atlas in 28 dry atlas specimens using micro-CT, in order to explain the mechanism of the predilection sites of atlas fractures from the morphological point of view. A total of 28 dry specimens of intact adult atlas were randomly selected, scanned by micro-CT, and divided into a region from the anterior arch midpoint (AAM) to the lateral masses (LM), a LM region, and a region from the LM to the posterior arch midpoint (PAM). Trabecular thickness, separation, number, connectivity, and structure model index were measured for each of the three regions using the built-in software of the CT scanner. Trabecular thickness was all measured to be 0.11 ± 0.00 mm for AAM to LM, LM, and LM to PAM. Trabecular separation: AAM to LM > LM to PAM > LM. Trabecular number: LM > LM to PAM > AAM to LM. Connectivity: LM > LM to PAM > AAM to LM. Structure model index: LM > LM to PAM > AAM to LM. A lower trabecular number and connectivity and higher trabecular separation were seen in the anterior and posterior arches of the atlas, in which higher fracture rates were reported. By contrast, a higher trabecular number and connectivity and lower trabecular separation were seen in the lateral masses, in which lower fracture rates were reported.


Este estudio tuvo como objetivo examinar las diferencias en la microarquitectura ósea entre diferentes regiones del atlas en 28 muestras de atlas secas utilizando micro-CT, con el fin de informar el área de mayor frecuencia en las fracturas de atlas, desde el punto de vista morfológico. Se seleccionaron al azar un total de 28 muestras secas de atlas adultos intactas las que se escanearon por micro-CT y se dividieron en una región desde el punto medio del arco anterior (MAA) hasta las masas laterales (ML), una región ML y una región desde el ML hasta el punto medio del arco posterior (MAP). Se midió el grosor trabecular, la separación, el número, la conectividad y el índice del modelo de estructura para cada una de las tres regiones utilizando el software incorporado del escáner CT. El grosor trabecular se midió en 0,11 ± 0,00 mm para MAA a ML, ML y ML a MAP. Separación trabecular: MAA a ML> ML a MAP> ML. Número trabecular: ML> ML a MAP> MAA a ML. Conectividad: ML> ML a MAP> MAA a ML. Índice del modelo de estructura: ML> ML a MAP> MAA a ML. Se observó un menor número de estructuras trabeculares y conectividad y una mayor separación trabecular en los arcos anterior y posterior del atlas, en los que se informaron tasas de fracturas más altas. Por el contrario, se observó un mayor número de estructuras trabeculares y conectividad, y una menor separación trabecular en las masas laterales, en las que se observó un número menor de fracturas.


Assuntos
Humanos , Atlas Cervical/diagnóstico por imagem , Microtomografia por Raio-X/métodos , Atlas Cervical/anatomia & histologia
13.
J Pediatr Orthop ; 40(4): 168-175, 2020 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-32132446

RESUMO

BACKGROUND: Two operative procedures are currently advocated to stimulate the necrotic femoral head healing in children with Legg-Calve-Perthes disease: transphyseal neck-head tunneling (TNHT) and multiple epiphyseal drilling (MED). The purpose of this study was to compare the bone healing and physeal function after treatment with TNHT or MED in a piglet model of ischemic osteonecrosis. METHODS: Eighteen piglets were induced with osteonecrosis by surgically placing a ligature tightly around the right femoral neck. One week later, the piglets were assigned to 1 of 3 treatment groups (n=6/group): (1) local nonweight bearing only (NWB), (2) TNHT plus NWB, or (3) MED plus NWB. The unoperated left femoral heads were used as normal controls. The animals were euthanized at 8 weeks after osteonecrosis induction. Histologic, histomorphometric, radiographic, microcomputed tomography (CT), and calcein-labeling assessments were performed. Statistical analysis included a 1-way ANOVA. RESULTS: Micro-CT analyses showed higher femoral head bone volume in the MED group compared with the TNHT and the NWB groups (P<0.01). The MED group had a higher mean trabecular number (P<0.001) and new bone formation (P=0.001) based on calcein-labeling parameters compared with the TNHT and the NWB groups. In addition, the osteoclast number per bone surface was lower in the MED group compared with the NWB group (P=0.001). Histologic and micro-CT assessments of the proximal femoral physis revealed a larger physeal disruption at the site of physeal drilling in the TNHT group compared with the MED group. However, no significant differences in physeal elongation (P=0.61) and femoral neck length (P=0.31) were observed between the treatment groups. CONCLUSIONS: MED produced a higher bone volume and stimulated greater bone formation than the TNHT or the NWB alone. Both procedures did not produce a significant physeal growth disturbance during the study period. CLINICAL RELEVANCE: This preclinical study provides evidence that MED produces more favorable bone healing than the TNHT in a large animal model of Legg-Calve-Perthes disease.


Assuntos
Cabeça do Fêmur , Doença de Legg-Calve-Perthes , Procedimentos Ortopédicos/métodos , Osteonecrose , Animais , Modelos Animais de Doenças , Epífises/patologia , Epífises/cirurgia , Cabeça do Fêmur/irrigação sanguínea , Cabeça do Fêmur/patologia , Cabeça do Fêmur/cirurgia , Necrose da Cabeça do Fêmur/patologia , Necrose da Cabeça do Fêmur/cirurgia , Lâmina de Crescimento/patologia , Lâmina de Crescimento/cirurgia , Humanos , Doença de Legg-Calve-Perthes/patologia , Doença de Legg-Calve-Perthes/cirurgia , Osteonecrose/diagnóstico , Osteonecrose/etiologia , Osteonecrose/cirurgia , Suínos , Resultado do Tratamento , Cicatrização , Microtomografia por Raio-X/métodos
14.
Sci Rep ; 10(1): 3960, 2020 03 03.
Artigo em Inglês | MEDLINE | ID: mdl-32127610

RESUMO

In the field of correlative microscopy, light and electron microscopy form a powerful combination for morphological analyses in zoology. Due to sample thickness limitations, these imaging techniques often require sectioning to investigate small animals and thereby suffer from various artefacts. A recently introduced nanoscopic X-ray computed tomography (NanoCT) setup has been used to image several biological objects, none that were, however, embedded into resin, which is prerequisite for a multitude of correlative applications. In this study, we assess the value of this NanoCT for correlative microscopy. For this purpose, we imaged a resin-embedded, meiofaunal sea cucumber with an approximate length of 1 mm, where microCT would yield only little information about the internal anatomy. The resulting NanoCT data exhibits isotropic 3D resolution, offers deeper insights into the 3D microstructure, and thereby allows for a complete morphological characterization. For comparative purposes, the specimen was sectioned subsequently to evaluate the NanoCT data versus serial sectioning light microscopy (ss-LM). To correct for mechanical instabilities and drift artefacts, we applied an alternative alignment procedure for CT reconstruction. We thereby achieve a level of detail on the subcellular scale comparable to ss-LM images in the sectioning plane.


Assuntos
Pepinos-do-Mar/ultraestrutura , Microtomografia por Raio-X/métodos , Animais , Imageamento Tridimensional , Microscopia , Microscopia Eletrônica
15.
Micron ; 133: 102861, 2020 06.
Artigo em Inglês | MEDLINE | ID: mdl-32146253

RESUMO

Granules of calcium/phosphate biomaterials are used to fill small bone defects in oral and maxilla-facial surgery. Granules of natural (e.g., trabecular bone, coral) or synthetic biomaterials are provided by industry. Small granules can also form of putty. The 3D geometry of granules creates a macroporosity allowing invasion of vascular and bone cells when pores are larger than 300 µm. We analyzed the 3D-porosity of 11 different stacks of biomaterials: Osteopure®, CopiOs®, Bio-Oss®, TCP Dental HP®, KeraOs®, TCH®, Biocoral®, EthOss® and Nanostim®. For each granular biomaterial, two sizes of granules were analyzed: small and large. Microcomputed tomography (microCT) determined porosity and microarchitectural characteristics of the biomaterials stacks. Computational fluid dynamics (CFD), a simulation method, was used on the stacks of microCT images. Stacks of small granules had a much lower permeation and fluid velocity than large granules and the hydraulic tortuosity was increased. Significant correlations were observed between microarchitecture parameters (porosity, mean pore diameter and specific surface) and fluid dynamic parameters. The two putties were associated with low (or absence of) porosity and permeation study revealed a very low (or absence) of flow rate. Stacks of granules represent 3D scaffolds resembling trabecular bone with an interconnected porous microarchitecture. Small granules create pores less than 300 µm in diameter; this induces a low fluid flow rate. CFD simulates the accessibility of body fluids and progenitor cells and confirms that it is depending on the shape and 3D arrangements of granules within a stack. Large granules must be preferred to putties and small granules.


Assuntos
Materiais Biocompatíveis/análise , Transplante Ósseo , Simulação por Computador , Hidrodinâmica , Microtomografia por Raio-X/métodos , Osso e Ossos , Fosfatos de Cálcio/análise , Humanos , Porosidade , Tecidos Suporte
16.
PLoS One ; 15(2): e0228962, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32084166

RESUMO

ChronoMID-neural networks for temporally-varying, hence Chrono, Medical Imaging Data-makes the novel application of cross-modal convolutional neural networks (X-CNNs) to the medical domain. In this paper, we present multiple approaches for incorporating temporal information into X-CNNs and compare their performance in a case study on the classification of abnormal bone remodelling in mice. Previous work developing medical models has predominantly focused on either spatial or temporal aspects, but rarely both. Our models seek to unify these complementary sources of information and derive insights in a bottom-up, data-driven approach. As with many medical datasets, the case study herein exhibits deep rather than wide data; we apply various techniques, including extensive regularisation, to account for this. After training on a balanced set of approximately 70000 images, two of the models-those using difference maps from known reference points-outperformed a state-of-the-art convolutional neural network baseline by over 30pp (> 99% vs. 68.26%) on an unseen, balanced validation set comprising around 20000 images. These models are expected to perform well with sparse data sets based on both previous findings with X-CNNs and the representations of time used, which permit arbitrarily large and irregular gaps between data points. Our results highlight the importance of identifying a suitable description of time for a problem domain, as unsuitable descriptors may not only fail to improve a model, they may in fact confound it.


Assuntos
Remodelação Óssea/fisiologia , Imageamento Tridimensional/métodos , Aprendizado de Máquina/estatística & dados numéricos , Animais , Interpretação Estatística de Dados , Aprendizado Profundo , Feminino , Camundongos , Camundongos Endogâmicos C57BL , Modelos Teóricos , Redes Neurais de Computação , Análise Espaço-Temporal , Microtomografia por Raio-X/métodos
17.
J Appl Oral Sci ; 28: e20190393, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32049137

RESUMO

OBJECTIVES: This study assessed the incidence and variability features of root canals system (RCS) and their ramifications according to Pucci & Reig (PR) (1944) and the American Association of Endodontists (AAE) (2017) by micro-computed tomography (µCT). METHODOLOGY: 500 representative extracted human teeth of each tooth group (n=50) (maxillary/mandibular central and lateral incisors, canines, first and second premolars and molars) were scanned by µCT with a resolution of 26.70 µm. The reconstructed cross-sections images and the visualization of the continuous slices in the transversal axis were performed using DataViewer software. RCS were classified according to Pucci & Reig (main canal, collateral canal, lateral canal, secondary canal, accessory canal, intercanal, recurrent canal) and AAE (main canal, accessory canal, lateral canal). The apical deltas were assessed for both classifications. The prevalence of apical deltas was evaluated using the Chi-squared test (p<0.05). RESULTS: According to PR, a higher incidence of lateral canals was observed in maxillary canines (10%), central incisors (8%) and first premolars (6%). Using AAE, the highest incidence of lateral canals was observed in the mandibular first premolars (85%), first and second molars (84%), lateral incisors (67%), canines (59%), and in maxillary first premolars (52%). Regarding accessory canals, the PR showed a frequency in 2% of the maxillary lateral incisors and maxillary and mandibular first premolars and 3% of mandibular first and second molars. On the other hand, the AAE showed the highest incidence of accessory canals in 86% of the maxillary first premolars, 71% in mandibular lateral incisors, 69% in mandibular first premolars, 65% in mandibular canines, and 56% in maxillary canines. The PR showed the lowest incidence of apical deltas for all dental groups when compared with AAE (p=0.004). Interestingly, distal canals in maxillary molars showed a significant discrepancy between classifications (p=0.027). CONCLUSIONS: µCT enabled accurately describing the RC system and related ramifications, adding to the PR and AAE classifications, with some discrepancies reported for maxillary molars. Clinical Relevance This µCT study enabled a thorough description of the variability among root canals and their ramifications, including clinically relevant details on the presence and location of lateral canals and accessories in all human tooth groups, beyond the currently existing classification systems.


Assuntos
Cavidade Pulpar/anatomia & histologia , Microtomografia por Raio-X/métodos , Cavidade Pulpar/diagnóstico por imagem , Humanos , Imageamento Tridimensional , Mandíbula/anatomia & histologia , Mandíbula/diagnóstico por imagem , Maxila/anatomia & histologia , Maxila/diagnóstico por imagem , Valores de Referência , Estatísticas não Paramétricas , Ápice Dentário/anatomia & histologia , Ápice Dentário/diagnóstico por imagem
18.
PLoS One ; 15(2): e0225019, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32097413

RESUMO

Small animal imaging has become essential in evaluating new cancer therapies as they are translated from the preclinical to clinical domain. However, preclinical imaging faces unique challenges that emphasize the gap between mouse and man. One example is the difference in breathing patterns and breath-holding ability, which can dramatically affect tumor burden assessment in lung tissue. As part of a co-clinical trial studying immunotherapy and radiotherapy in sarcomas, we are using micro-CT of the lungs to detect and measure metastases as a metric of disease progression. To effectively utilize metastatic disease detection as a metric of progression, we have addressed the impact of respiratory gating during micro-CT acquisition on improving lung tumor detection and volume quantitation. Accuracy and precision of lung tumor measurements with and without respiratory gating were studied by performing experiments with in vivo images, simulations, and a pocket phantom. When performing test-retest studies in vivo, the variance in volume calculations was 5.9% in gated images and 15.8% in non-gated images, compared to 2.9% in post-mortem images. Sensitivity of detection was examined in images with simulated tumors, demonstrating that reliable sensitivity (true positive rate (TPR) ≥ 90%) was achievable down to 1.0 mm3 lesions with respiratory gating, but was limited to ≥ 8.0 mm3 in non-gated images. Finally, a clinically-inspired "pocket phantom" was used during in vivo mouse scanning to aid in refining and assessing the gating protocols. Application of respiratory gating techniques reduced variance of repeated volume measurements and significantly improved the accuracy of tumor volume quantitation in vivo.


Assuntos
Neoplasias Pulmonares/diagnóstico por imagem , Técnicas de Imagem de Sincronização Respiratória/métodos , Microtomografia por Raio-X/métodos , Animais , Confiabilidade dos Dados , Modelos Animais de Doenças , Medidas de Volume Pulmonar , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Transgênicos , Imagens de Fantasmas , Sensibilidade e Especificidade , Microtomografia por Raio-X/instrumentação
19.
Int J Oral Sci ; 12(1): 5, 2020 02 06.
Artigo em Inglês | MEDLINE | ID: mdl-32024813

RESUMO

Rheumatoid arthritis (RA) is an autoimmune disease affecting 1% of the world population and is characterized by chronic inflammation of the joints sometimes accompanied by extra-articular manifestations. K/BxN mice, originally described in 1996 as a model of polyarthritis, exhibit knee joint alterations. The aim of this study was to describe temporomandibular joint (TMJ) inflammation and damage in these mice. We used relevant imaging modalities, such as micro-magnetic resonance imaging (µMRI) and micro-computed tomography (µCT), as well as histology and immunofluorescence techniques to detect TMJ alterations in this mouse model. Histology and immunofluorescence for Col-I, Col-II, and aggrecan showed cartilage damage in the TMJ of K/BxN animals, which was also evidenced by µCT but was less pronounced than that seen in the knee joints. µMRI observations suggested an increased volume of the upper articular cavity, an indicator of an inflammatory process. Fibroblast-like synoviocytes (FLSs) isolated from the TMJ of K/BxN mice secreted inflammatory cytokines (IL-6 and IL-1ß) and expressed degradative mediators such as matrix metalloproteinases (MMPs). K/BxN mice represent an attractive model for describing and investigating spontaneous damage to the TMJ, a painful disorder in humans with an etiology that is still poorly understood.


Assuntos
Artrite Experimental/patologia , Artrite Reumatoide/patologia , Osso e Ossos/diagnóstico por imagem , Articulação Temporomandibular/diagnóstico por imagem , Articulação Temporomandibular/lesões , Microtomografia por Raio-X/métodos , Animais , Artrite Experimental/imunologia , Artrite Reumatoide/imunologia , Osso e Ossos/metabolismo , Osso e Ossos/patologia , Modelos Animais de Doenças , Humanos , Imagem por Ressonância Magnética , Metaloproteinase 8 da Matriz/imunologia , Camundongos , Camundongos Transgênicos , Articulação Temporomandibular/metabolismo , Tomografia Computadorizada por Raios X
20.
Breast Cancer Res Treat ; 180(2): 343-357, 2020 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-32020431

RESUMO

PURPOSE: The goal of breast cancer surgery is to remove all of the cancer with a minimum of normal tissue, but absence of full 3-dimensional information on the specimen makes this difficult to achieve. METHOD: Micro-CT is a high resolution, X-ray, 3D imaging method, widely used in industry but rarely in medicine. RESULTS: We imaged and analyzed 173 partial mastectomies (129 ductal carcinomas, 14 lobular carcinomas, 28 DCIS). Imaging was simple and rapid. The size and shape of the cancers seen on Micro-CT closely matched the size and shape of the cancers seen at specimen dissection. Micro-CT images of multicentric/multifocal cancers revealed multiple non-contiguous masses. Micro-CT revealed cancer touching the specimen edge for 93% of the 114 cases judged margin positive by the pathologist, and 28 of the cases not seen as margin positive on pathological analysis; cancer occupied 1.55% of surface area when both the pathologist and Micro-CT suggested cancer at the edge, but only 0.45% of surface area for the "Micro-CT-Only-Positive Cases". Thus, Micro-CT detects cancers that touch a very small region of the specimen surface, which is likely to be missed on sectioning. CONCLUSIONS: Micro-CT provides full 3D images of breast cancer specimens, allowing one to identify, in minutes rather than hours, while the patient is in OR, margin-positive cancers together with information on where the cancer touches the edge, in a fashion more accurate than possible from the histology slides alone.


Assuntos
Neoplasias da Mama/patologia , Carcinoma Ductal/patologia , Carcinoma Lobular/patologia , Imageamento Tridimensional/métodos , Mastectomia Segmentar/métodos , Interpretação de Imagem Radiográfica Assistida por Computador/métodos , Microtomografia por Raio-X/métodos , Neoplasias da Mama/diagnóstico por imagem , Neoplasias da Mama/cirurgia , Carcinoma Ductal/diagnóstico por imagem , Carcinoma Ductal/cirurgia , Carcinoma Lobular/diagnóstico por imagem , Carcinoma Lobular/cirurgia , Feminino , Humanos , Período Intraoperatório , Margens de Excisão , Estadiamento de Neoplasias , Manejo de Espécimes
SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA