Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 208
Filtrar
1.
J Synchrotron Radiat ; 31(Pt 5): 1293-1298, 2024 Sep 01.
Artigo em Inglês | MEDLINE | ID: mdl-39007822

RESUMO

Two-directional beam-tracking (2DBT) is a method for phase-contrast imaging and tomography that uses an intensity modulator to structure the X-ray beam into an array of independent circular beamlets that are resolved by a high-resolution detector. It features isotropic spatial resolution, provides two-dimensional phase sensitivity, and enables the three-dimensional reconstructions of the refractive index decrement, δ, and the attenuation coefficient, µ. In this work, the angular sensitivity and the spatial resolution of 2DBT images in a synchrotron-based implementation is reported. In its best configuration, angular sensitivities of ∼20 nrad and spatial resolution of at least 6.25 µm in phase-contrast images were obtained. Exemplar application to the three-dimensional imaging of soft tissue samples, including a mouse liver and a decellularized porcine dermis, is also demonstrated.


Assuntos
Imageamento Tridimensional , Síncrotrons , Microtomografia por Raio-X , Animais , Camundongos , Microtomografia por Raio-X/métodos , Imageamento Tridimensional/métodos , Fígado/diagnóstico por imagem , Suínos
2.
J Synchrotron Radiat ; 31(Pt 1): 186-194, 2024 Jan 01.
Artigo em Inglês | MEDLINE | ID: mdl-37971957

RESUMO

Here, high-throughput tomography (HiTT), a fast and versatile phase-contrast imaging platform for life-science samples on the EMBL beamline P14 at DESY in Hamburg, Germany, is presented. A high-photon-flux undulator beamline is used to perform tomographic phase-contrast acquisition in about two minutes which is linked to an automated data processing pipeline that delivers a 3D reconstructed data set less than a minute and a half after the completion of the X-ray scan. Combining this workflow with a sophisticated robotic sample changer enables the streamlined collection and reconstruction of X-ray imaging data from potentially hundreds of samples during a beam-time shift. HiTT permits optimal data collection for many different samples and makes possible the imaging of large sample cohorts thus allowing population studies to be attempted. The successful application of HiTT on various soft tissue samples in both liquid (hydrated and also dehydrated) and paraffin-embedded preparations is demonstrated. Furthermore, the feasibility of HiTT to be used as a targeting tool for volume electron microscopy, as well as using HiTT to study plant morphology, is demonstrated. It is also shown how the high-throughput nature of the work has allowed large numbers of `identical' samples to be imaged to enable statistically relevant sample volumes to be studied.


Assuntos
Robótica , Síncrotrons , Raios X , Tomografia Computadorizada por Raios X , Alemanha
3.
J Anat ; 245(2): 271-288, 2024 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-38613211

RESUMO

Auditory sensitivity and frequency resolution depend on the optimal transfer of sound-induced vibrations from the basilar membrane (BM) to the inner hair cells (IHCs), the principal auditory receptors. There remains a paucity of information on how this is accomplished along the frequency range in the human cochlea. Most of the current knowledge is derived either from animal experiments or human tissue processed after death, offering limited structural preservation and optical resolution. In our study, we analyzed the cytoarchitecture of the human cochlear partition at different frequency locations using high-resolution microscopy of uniquely preserved normal human tissue. The results may have clinical implications and increase our understanding of how frequency-dependent acoustic vibrations are carried to human IHCs. A 1-micron-thick plastic-embedded section (mid-modiolar) from a normal human cochlea uniquely preserved at lateral skull base surgery was analyzed using light and transmission electron microscopy (LM, TEM). Frequency locations were estimated using synchrotron radiation phase-contrast imaging (SR-PCI). Archival human tissue prepared for scanning electron microscopy (SEM) and super-resolution structured illumination microscopy (SR-SIM) were also used and compared in this study. Microscopy demonstrated great variations in the dimension and architecture of the human cochlear partition along the frequency range. Pillar cell geometry was closely regulated and depended on the reticular lamina slope and tympanic lip angle. A type II collagen-expressing lamina extended medially from the tympanic lip under the inner sulcus, here named "accessory basilar membrane." It was linked to the tympanic lip and inner pillar foot, and it may contribute to the overall compliance of the cochlear partition. Based on the findings, we speculate on the remarkable microanatomic inflections and geometric relationships which relay different sound-induced vibrations to the IHCs, including their relevance for the evolution of human speech reception and electric stimulation with auditory implants. The inner pillar transcellular microtubule/actin system's role of directly converting vibration energy to the IHC cuticular plate and ciliary bundle is highlighted.


Assuntos
Cóclea , Órgão Espiral , Humanos , Cóclea/anatomia & histologia , Cóclea/fisiologia , Órgão Espiral/anatomia & histologia , Órgão Espiral/fisiologia , Microscopia Eletrônica de Varredura , Microscopia Eletrônica de Transmissão , Transdução de Sinais/fisiologia , Membrana Basilar/anatomia & histologia , Membrana Basilar/fisiologia
4.
Audiol Neurootol ; : 1-13, 2024 May 22.
Artigo em Inglês | MEDLINE | ID: mdl-38763131

RESUMO

INTRODUCTION: Otosclerosis is a bone disorder affecting the labyrinthine capsule that leads to conductive and occasionally sensorineural hearing loss. The etiology of otosclerosis remains unknown; factors such as infection, hormones, inflammation, genetics, and autoimmunity have been discussed. Treatment consists primarily of surgical stapes replacement and cochlear implantation. High-resolution computed tomography is routinely used to visualize bone pathology. In the present study, we used synchrotron radiation phase-contrast imaging (SR-PCI) to examine otosclerosis plaques in a temporal bone for the first time. The primary aim was to study their three-dimensional (3D) outline, vascular interrelationships, and connections to the middle ear. METHODS: A donated ear from a patient with otosclerosis who had undergone partial stapedectomy with the insertion of a stapes wire prosthesis was investigated using SR-PCI and compared with a control ear. Otosclerotic lesions were 3D rendered using the composite with shading technique. Scalar opacity and color mapping were adjusted to display volume properties with the removal of bones to enhance surfaces. Vascular bone channels were segmented, and the communications between lesions and the middle ear were established. RESULTS: Fenestral, cochlear, meatal, and vestibular lesions were outlined three-dimensionally. Vascular bone channels were found to be frequently connected to the middle ear mucosa, perilabyrinthine air spaces, and facial nerve vessels. Round window lesions partly embedded the cochlear aqueduct which was pathologically narrowed, while the inferior cochlear vein was significantly dilated in its proximal part. CONCLUSION: Otosclerotic/otospongiotic lesions were imaged for the first time using SR-PCI and 3D rendering. The presence of shunts and abnormal vascular connections to the labyrinth appeared to result in hyper-vascularization, overloading the venous system, and leading to sensorineural hearing loss. We speculate about possible local treatments to alleviate the impact of such critical lesions on the labyrinthine microcirculation.

5.
Curr Cardiol Rep ; 26(5): 413-421, 2024 May.
Artigo em Inglês | MEDLINE | ID: mdl-38517604

RESUMO

PURPOSE OF REVIEW: Cardiac magnetic resonance (CMR) is emerging as a valuable imaging modality for the assessment of aortic regurgitation (AR). In this review, we discuss the assessment of AR severity, left ventricular (LV) remodeling, and tissue characterization by CMR while highlighting the latest studies and addressing future research needs. RECENT FINDINGS: Recent studies have further established CMR-based thresholds of AR severity and LV remodeling that are associated with adverse clinical outcomes, and lower than current guideline criteria. In addition, tissue profiling with late gadolinium enhancement (LGE) and extracellular volume (ECV) quantification can reliably assess adverse myocardial tissue remodeling which is also associated with adverse outcomes. The strengths and reproducibility of CMR in evaluating ventricular volumes, tissue characteristics, and regurgitation severity position it as an excellent modality in evaluating and following AR patients. Advanced CMR techniques for the detection of tissue remodeling have shown significant potential and merit further investigation.


Assuntos
Insuficiência da Valva Aórtica , Fibrose , Índice de Gravidade de Doença , Remodelação Ventricular , Humanos , Insuficiência da Valva Aórtica/diagnóstico por imagem , Insuficiência da Valva Aórtica/fisiopatologia , Fibrose/diagnóstico por imagem , Imagem Cinética por Ressonância Magnética/métodos , Imageamento por Ressonância Magnética/métodos , Reprodutibilidade dos Testes , Meios de Contraste
6.
Nano Lett ; 23(7): 2991-2997, 2023 Apr 12.
Artigo em Inglês | MEDLINE | ID: mdl-36971648

RESUMO

Spiral phase contrast imaging and bright-field imaging are two widely used modes in microscopy, providing distinct morphological information about objects. However, conventional microscopes are always unable to operate with these two modes at the same time and need additional optical elements to switch between them. Here, we present a microscopy setup that incorporates a dielectric metasurface capable of achieving spiral phase contrast imaging and bright-field imaging synchronously. The metasurface not only can focus the light for diffraction-limited imaging but also can perform a two-dimensional spatial differentiation operation by imparting an orbital angular momentum to the incident light field. This allows two spatially separated images to be simultaneously obtained, one containing high-frequency edge information and the other showing the entirety of the object. Combined with the advantages of planar architecture and ultrathin thickness of the metasurface, this approach is expected to provide support in the fields of microscopy, biomedicine, and materials science.

7.
Nano Lett ; 23(24): 11630-11637, 2023 Dec 27.
Artigo em Inglês | MEDLINE | ID: mdl-38038680

RESUMO

Phase contrast imaging techniques enable the visualization of disparities in the refractive index among various materials. However, these techniques usually come with a cost: the need for bulky, inflexible, and complicated configurations. Here, we propose and experimentally demonstrate an ultracompact meta-microscope, a novel imaging platform designed to accomplish both optical and digital phase contrast imaging. The optical phase contrast imaging system is composed of a pair of metalenses and an intermediate spiral phase metasurface located at the Fourier plane. The performance of the system in generating edge-enhanced images is validated by imaging a variety of human cells, including lung cell lines BEAS-2B, CLY1, and H1299 and other types. Additionally, we integrate the ResNet deep learning model into the meta-microscope to transform bright-field images into edge-enhanced images with high contrast accuracy. This technology promises to aid in the development of innovative miniature optical systems for biomedical and clinical applications.


Assuntos
Microscopia , Dispositivos Ópticos , Humanos , Microscopia/métodos , Microscopia de Contraste de Fase/métodos , Imagem Óptica
8.
Surg Radiol Anat ; 2024 Sep 03.
Artigo em Inglês | MEDLINE | ID: mdl-39225863

RESUMO

PURPOSE: To date, no non-invasive imaging modality has been employed to profile the structural intricacies of the hippocampal arterial microvasculature in humans. We hypothesised that synchrotron-based imaging of the human hippocampus would enable precise characterisation of the arterial microvasculature. METHODS: Two preserved human brains from, a 69-year-old female and a 63-year-old male body donors were imaged using hierarchical phase-contrast tomography (HiP-CT) with synchrotron radiation at multiple voxel resolutions from 25.08 µm down to 2.45 µm. Subsequent manual and semi-automatic artery segmentation were performed followed by morphometric analyses. These data were compared to published data from alternative methodologies. RESULTS: HiP-CT made it possible to segment in context the arterial architecture of the human hippocampus. Our analysis identified anterior, medial and posterior hippocampal arteries arising from the P2 segment of the posterior cerebral artery on the image slices. We mapped arterial branches with external diameters greater than 50 µm in the hippocampal region. We visualised vascular asymmetry and quantified arterial structures with diameters as small as 7 µm. CONCLUSIONS: Through the application of HiP-CT, we have provided the first imaging visualisation and quantification of the arterial system of the human hippocampus at high resolution in the context of whole brain imaging. Our results bridge the gap between anatomical and histological scales.

9.
J Xray Sci Technol ; 32(4): 1163-1175, 2024.
Artigo em Inglês | MEDLINE | ID: mdl-38943421

RESUMO

BACKGROUND: Typical propagation-based X-ray phase contrast imaging (PB-PCI) experiments using polyenergetic sources are tested in very ideal conditions: low-energy spectrum (mainly characteristic X-rays), small thickness and homogeneous materials considered weakly absorbing objects, large object-to-detector distance, long exposure times and non-clinical detector. OBJECTIVE: Explore PB-PCI features using boundary conditions imposed by a low power polychromatic X-ray source (X-ray spectrum without characteristic X-rays), thick and heterogenous materials and a small area imaging detector with high low-detection radiation threshold, elements commonly found in a clinical scenario. METHODS: A PB-PCI setup implemented using a microfocus X-ray source and a dental imaging detector was characterized in terms of different spectra and geometric parameters on the acquired images. Test phantoms containing fibers and homogeneous materials with close attenuation characteristics and animal bone and mixed soft tissues (bio-sample models) were analyzed. Contrast to Noise Ratio (CNR), system spatial resolution and Kerma values were obtained for all images. RESULTS: Phase contrast images showed CNR up to 15% higher than conventional contact images. Moreover, it is better seen when large magnifications (>3) and object-to-detector distances (>13 cm) were used. The influence of the spectrum was not appreciable due to the low efficiency of the detector (thin scintillator screen) at high energies. CONCLUSIONS: Despite the clinical boundary condition used in this work, regarding the X-ray spectrum, thick samples, and detection system, it was possible to acquire phase contrast images of biological samples.


Assuntos
Imagens de Fantasmas , Animais , Raios X , Humanos
10.
Histochem Cell Biol ; 160(5): 377-389, 2023 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-37523091

RESUMO

X-ray phase contrast imaging (X-PCI) is a powerful technique for high-resolution, three-dimensional imaging of soft tissue samples in a non-destructive manner. In this technical report, we assess the quality of standard histopathological techniques performed on formalin-fixed, paraffin-embedded (FFPE) human tissue samples that have been irradiated with different doses of X-rays in the context of an X-PCI experiment. The data from this study demonstrate that routine histochemical and immunohistochemical staining quality as well as DNA and RNA analyses are not affected by previous X-PCI on human FFPE samples. From these data we conclude it is feasible and acceptable to perform X-PCI on FFPE human biopsies.


Assuntos
Intervenção Coronária Percutânea , Síncrotrons , Humanos , Raios X , Estudos de Viabilidade , Imageamento Tridimensional , Inclusão em Parafina , Formaldeído , Fixação de Tecidos
11.
J Magn Reson Imaging ; 2023 Sep 30.
Artigo em Inglês | MEDLINE | ID: mdl-37776094

RESUMO

BACKGROUND: Motor units (MUs) control the contraction of muscles and degenerate with age. It is therefore of interest to measure whole muscle and MU twitch profiles in aging skeletal muscle. PURPOSE: Apply phase contrast MU MRI (PC-MUMRI) in a cohort of healthy adults to measure whole anterior compartment, individual muscles, and single MU twitch profiles in the calf. Assess the effect of age and sex on contraction and relaxation times. STUDY TYPE: Prospective cross-sectional study. SUBJECTS: Sixty-one healthy participants (N = 32 male; age 55 ± 16 years [range: 26-82]). FIELD STRENGTH/SEQUENCES: 3 T, velocity encoded gradient echo and single shot spin echo pulsed gradient spin echo, echo-planar imaging. ASSESSMENT: Anterior shin compartment (N = 47), individual muscle (tibialis anterior, extensor digitorum longus, peroneus longus; N = 47) and single MU (N = 34) twitch profiles were extracted from the data to calculate contraction and relaxation times. STATISTICAL TESTS: Multivariable linear regression to investigate relationships between age, sex and contraction and relaxation times of the whole anterior compartment. Pearson correlation to investigate relationships between age and contraction and relaxation times of individual muscles and single MUs. A P value <0.05 was considered statistically significant. RESULTS: Age and sex predicted significantly increased contraction and relaxation time for the anterior compartment. Females had significantly longer contraction times than males (females 86 ± 8 msec, males 80 ± 9 msec). Relaxation times were longer, not significant (females 204 ± 36 msec, males 188 ± 34 msec, P = 0.151). Contraction and relaxation times of single MUs showed no change with age (P = 0.462, P = 0.534, respectively). DATE CONCLUSION: Older participants had significantly longer contraction and relaxation times of the whole anterior compartment compared to younger participants. Females had longer contraction and relaxation times than males, significant for contraction time. EVIDENCE LEVEL: 2 TECHNICAL EFFICACY: Stage 1.

12.
Transpl Int ; 36: 11046, 2023.
Artigo em Inglês | MEDLINE | ID: mdl-36762268

RESUMO

Endomyocardial biopsies are the gold standard for surveillance of graft rejection following heart transplantation, and are assessed by classical histopathology using a limited number of previously stained slices from several biopsies. Synchrotron propagation-based X-ray phase contrast imaging is a non-destructive method to image biological samples without tissue preparation, enabling virtual 2D and 3D histopathology. We aimed to show the feasibility of this method to assess acute cellular rejection and its agreement to classical histopathology. Right ventricular biopsies were sampled from 23 heart transplantation recipients (20 males, mean age 54±14 years) as part of standard follow-up. The clinical diagnosis of potential rejection was made using classical histopathology. One additional study sample was harvested and imaged by X-ray phase contrast imaging, producing 3D datasets with 0.65 µm pixel size, and up to 4,320 images per sample. An experienced pathologist graded both histopathological and X-ray phase contrast images in a blinded fashion. The agreement between methods was assessed by weighted kappa, showing substantial agreement (kappa up to 0.80, p < 0.01) between X-ray phase contrast imaging and classical histopathology. X-ray phase contrast imaging does not require tissue processing, allows thorough analysis of a full myocardial sample and allows identification of acute cellular rejection.


Assuntos
Transplante de Coração , Masculino , Humanos , Adulto , Pessoa de Meia-Idade , Idoso , Seguimentos , Raios X , Biópsia , Rejeição de Enxerto/diagnóstico por imagem , Rejeição de Enxerto/patologia , Imageamento Tridimensional
13.
Pediatr Radiol ; 53(10): 2040-2047, 2023 09.
Artigo em Inglês | MEDLINE | ID: mdl-37271756

RESUMO

BACKGROUND: Measurement of differential blood flow to the lungs is important to understanding flow dynamics in the setting of congenital heart disease. Split blood flow via the pulmonary arteries guides and demonstrates the effect of interventions. Minimally invasive imaging of pulmonary blood flow can be achieved with scintigraphy or magnetic resonance imaging (MRI). OBJECTIVE: To assess agreement of pulmonary blood flow measurements obtained by scintigraphy and MRI in children and young adults. MATERIALS AND METHODS: We performed a retrospective review of patients < 21 years of age who had undergone both nuclear medicine pulmonary perfusion scans (Tc-99 m MAA) and cardiac MRI examinations from January 2012 to August 2021 at our tertiary pediatric hospital. Patient demographics, medical/surgical information, and estimates of split blood flow by both modalities were recorded. Pearson's correlation coefficient was used to determine the relationship between split blood flow measured by the two examinations. Agreement was calculated using interclass correlation coefficient (ICC) for absolute agreement and Bland-Altman difference analysis. RESULTS: Correlation between split blood flow measured by scintigraphy and MRI using net flow was 0.90 (95% CI: 0.83-0.94, P < 0.001) and the ICC for agreement on split blood flow was 0.90 (95% CI: 0.84-0.94). Mean difference in split blood flow by Bland-Altman analysis was 0.79% with 95% limits of agreement (-11.2 to 12.8%). CONCLUSION: There is excellent agreement between Tc-99 m scintigraphy and phase contrast MRI for quantification of split pulmonary blood flow in children and young adults with congenital heart disease.


Assuntos
Cardiopatias Congênitas , Circulação Pulmonar , Criança , Humanos , Adulto Jovem , Circulação Pulmonar/fisiologia , Imageamento por Ressonância Magnética/métodos , Cintilografia , Pulmão , Cardiopatias Congênitas/diagnóstico por imagem , Reprodutibilidade dos Testes
14.
Sensors (Basel) ; 23(6)2023 Mar 14.
Artigo em Inglês | MEDLINE | ID: mdl-36991826

RESUMO

X-ray grating interferometry (XGI) can provide multiple image modalities. It does so by utilizing three different contrast mechanisms-attenuation, refraction (differential phase-shift), and scattering (dark-field)-in a single dataset. Combining all three imaging modalities could create new opportunities for the characterization of material structure features that conventional attenuation-based methods are unable probe. In this study, we proposed an image fusion scheme based on the non-subsampled contourlet transform and spiking cortical model (NSCT-SCM) to combine the tri-contrast images retrieved from XGI. It incorporated three main steps: (i) image denoising based on Wiener filtering, (ii) the NSCT-SCM tri-contrast fusion algorithm, and (iii) image enhancement using contrast-limited adaptive histogram equalization, adaptive sharpening, and gamma correction. The tri-contrast images of the frog toes were used to validate the proposed approach. Moreover, the proposed method was compared with three other image fusion methods by several figures of merit. The experimental evaluation results highlighted the efficiency and robustness of the proposed scheme, with less noise, higher contrast, more information, and better details.

15.
J Xray Sci Technol ; 31(6): 1341-1362, 2023.
Artigo em Inglês | MEDLINE | ID: mdl-37840465

RESUMO

BACKGROUNDS: X-ray phase contrast imaging (XPCI) can separate the attenuation, refraction, and scattering signals of the object. The application of image fusion enables the concentration of distinctive information into a single image. Some methods have been applied in XPCI field, but wavelet-based decomposition approaches often result in loss of original data. OBJECTIVE: To explore the application value of a novel image fusion method for XPCI system and computed tomography (CT) system. METHODS: The means of fast adaptive bidimensional empirical mode decomposition (FABEMD) is considered for image decomposition to avoid unnecessary information loss. A parameter δ is proposed to guide the fusion of bidimensional intrinsic mode functions which contain high-frequency information, using a pulse coupled neural network with morphological gradients (MGPCNN). The residual images are fused by the energy attribute fusion strategy. Image preprocessing and enhancement are performed on the result to ensure its quality. The effectiveness of other image fusion methods has been compared, such as discrete wavelet transforms and anisotropic diffusion fusion. RESULTS: The δ-guided FABEMD-MGPCNN method achieved either the first or second position in objective evaluation metrics with biological samples, as compared to other image fusion methods. Moreover, comparisons are made with other fusion methods used for XPCI. Finally, the proposed method applied in CT show expected results to retain the feature information. CONCLUSIONS: The proposed δ-guided FABEMD-MGPCNN method shows potential feasibility and superiority over traditional and recent image fusion methods for X-ray differential phase contrast imaging and computed tomography systems.


Assuntos
Algoritmos , Tomografia Computadorizada por Raios X , Raios X , Tomografia Computadorizada por Raios X/métodos , Redes Neurais de Computação , Análise de Ondaletas , Processamento de Imagem Assistida por Computador/métodos
16.
J Synchrotron Radiat ; 29(Pt 2): 480-487, 2022 Mar 01.
Artigo em Inglês | MEDLINE | ID: mdl-35254312

RESUMO

Over the last decade ptychography has progressed rapidly from a specialist ultramicroscopy technique into a mature method accessible to non-expert users. However, to improve scientific value ptychography data must reconstruct reliably, with high image quality and at no cost to other correlative methods. Presented here is the implementation of high-speed ptychography used at the Australian Synchrotron on the XFM beamline, which includes a free-run data collection mode where dead time is eliminated and the scan time is optimized. It is shown that free-run data collection is viable for fast and high-quality ptychography by demonstrating extremely high data rate acquisition covering areas up to 352 000 µm2 at up to 140 µm2 s-1, with 13× spatial resolution enhancement compared with the beam size. With these improvements, ptychography at velocities up to 250 µm s-1 is approaching speeds compatible with fast-scanning X-ray fluorescence microscopy. The combination of these methods provides morphological context for elemental and chemical information, enabling unique scientific outcomes.


Assuntos
Microscopia , Síncrotrons , Austrália , Microscopia/métodos
17.
Nanotechnology ; 34(4)2022 Nov 07.
Artigo em Inglês | MEDLINE | ID: mdl-36260979

RESUMO

High-resolution, x-ray phase contrast microscopy, a key technique with promising potential in biomedical imaging and diagnostics, is based on narrow-slit high-aspect-ratio gold gratings. We present the development, fabrication details, and experimental testing of the freestanding 10µm thick gold membrane masks with an array of 0.9-1.5µm void slit apertures for a novel low-energy x-ray microscope. The overall mask size is 4 mm × 4 mm, with a grating pitch of 7.5µm, 6.0-6.6µm wide gold bars are supported by 3µm wide crosslinks at 400µm intervals. The fabrication process is based on gold electroplating into a silicon mold coated with various thin films to form a voltage barrier, plating base, and sacrificial layer, followed by the mold removal to obtain the freestanding gold membrane with void slit apertures. We discuss key aspects for the materials and processes, including gold structures homogeneity, residual stresses, and prevention of collapsing of the grid elements. We further demonstrate the possibility to obtain high-resolution, high contrast 2D images of biological samples using an incoherent, rotating anode x-ray tube.

18.
Artigo em Inglês | MEDLINE | ID: mdl-35835512

RESUMO

Optimal decision-making to determine the type and timing of surgical intervention for various congenital heart disease (CHD) requires adequate understanding and interpretation of anatomic and physiologic data obtained from various imaging modalities. Cardiac magnetic resonance (CMR) has revolutionized the way we evaluate the anatomy and physiology of CHD. In addition to 2- and 3-dimensional anatomic data and volumetry, phase-contrast CMR allows quantitative measurements of cardiac output, pulmonary blood flow, pulmonary-to-systemic flow ratio, the amount of intracardiac shunt, valve regurgitation, and aortopulmonary collateral flows. This review article describes the utilization of CMR-derived flow data in surgical decision-making in three distinct subgroups: (1) patients with borderline left ventricle (LV) with emphasis on the ascending aortic flow and other physiologic parameters, (2) single ventricle patients who undergo bidirectional cavopulmonary shunt with emphasis on the impact of superior vena cava blood flow on postoperative physiology, and (3) patients with pulmonary atresia and major aortopulmonary collateral arteries with emphasis on the impact of total pulmonary blood flow and systemic-to-pulmonary flow ratio on clinical outcomes.


Assuntos
Tomada de Decisão Clínica , Técnica de Fontan , Cardiopatias Congênitas , Cardiopatias Congênitas/cirurgia , Humanos , Artéria Pulmonar/cirurgia , Circulação Pulmonar , Veia Cava Superior/cirurgia
19.
Sensors (Basel) ; 22(15)2022 Aug 07.
Artigo em Inglês | MEDLINE | ID: mdl-35957449

RESUMO

In this work, we investigate the potential of employing a direct conversion integration mode X-ray detector with micron-scale pixels in two different X-ray phase-contrast imaging (XPCi) configurations, propagation-based (PB) and edge illumination (EI). Both PB-XPCi and EI-XPCi implementations are evaluated through a wave optics model-numerically simulated in MATLAB-and are compared based on their contrast, edge-enhancement, visibility, and dose efficiency characteristics. The EI-XPCi configuration, in general, demonstrates higher performance compared to PB-XPCi, considering a setup with the same X-ray source and detector. However, absorption masks quality (thickness of X-ray absorption material) and environmental vibration effect are two potential challenges for EI-XPCi employing a detector with micron-scale pixels. Simulation results confirm that the behavior of an EI-XPCi system employing a high-resolution detector is susceptible to its absorption masks thickness and misalignment. This work demonstrates the potential and feasibility of employing a high-resolution direct conversion detector for phase-contrast imaging applications where higher dose efficiency, higher contrast images, and a more compact imaging system are of interest.


Assuntos
Iluminação , Simulação por Computador , Radiografia , Raios X
20.
J Digit Imaging ; 35(2): 365-373, 2022 04.
Artigo em Inglês | MEDLINE | ID: mdl-35064371

RESUMO

Detecting low-density foreign bodies within soft tissues still stands for a serious challenge. Grating-based multimodal X-ray imaging typically has low hardware requirements while simultaneously providing three kinds of imaging information, i.e., absorption, phase-contrast, and dark-field. We aimed to explore the capacity of grating-based multimodal X-ray imaging technology for detecting common foreign bodies within subcutaneous tissues, and to assess the advantages as well as disadvantages of the three kinds of images obtained via grating-based X-ray multimodal technology in relation to diverse kinds of foreign bodies within different tissues. In this study, metal, glass, wood, plastic, graphite, and ceramic foreign bodies were injected into chunks of the pig adipose tissue and chicken thigh muscles. Next, a grating-based multimodal X-ray imaging device developed in our laboratory was used to detect the above foreign bodies within the adipose and muscle tissues. Our results show that grating-based multimodal X-ray imaging clearly revealed the subcutaneous foreign bodies within the adipose and muscle tissues by acquiring complementary absorption, phase-contrast, and dark-field imaging data in a single shot. Grating-based multimodal X-ray imaging has an exciting potential to detect foreign bodies underneath the epidermis.


Assuntos
Corpos Estranhos , Tela Subcutânea , Animais , Corpos Estranhos/diagnóstico por imagem , Humanos , Radiografia , Suínos , Raios X
SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA