Evaluation of 2D super-resolution ultrasound imaging of the rat renal vasculature using ex vivo micro-computed tomography.
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ABSTRACT:
SUBMITTER: Andersen SB
PROVIDER: S-EPMC8692475 | biostudies-literature |
REPOSITORIES: biostudies-literature
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Project description:Alterations at the level of the coronary circulation with aging may play an important role in the evolution of age-associated changes in left ventricular (LV) fibrosis and function. However these age-associated changes in the coronary vasculature remain poorly defined primarily due to the lack of high resolution imaging technologies. The current study was designed to utilize cardiac micro-computed tomography (micro-CT) technology as a novel imaging strategy, to define the 3-dimensional coronary circulation in the young and aged heart and its relationship to LV fibrosis and function.Young (2 months old; n=10) and aged (20 months old; n=10) Fischer rats underwent cardiac micro-CT imaging as well as echocardiography, blood pressure, and fibrosis analysis. Importantly, when indexed to LV mass, which increased with age, the total and intramyocardial vessel volumes were lower, whereas the epicardial vessel volume, with and without indexing to LV mass, was significantly higher in the aged hearts compared with the young hearts. Moreover, the aged hearts had a significantly lower percentage of intramyocardial vessel volume and a significantly higher percentage of epicardial vessel volume, when normalized to the total vessel volume, compared with the young hearts. Further, the aged hearts had significant LV fibrosis and mild LV dysfunction compared with the young hearts.This micro-CT imaging study reports the reduction in normalized intramyocardial vessel volume within the aged heart, in association with increased epicardial vessel volume, in the setting of increased LV fibrosis, and mild LV dysfunction.
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Project description:ObjectiveThe choroidal vessels, which supply oxygen and nutrient to the retina, may play a pivotal role in eye disease pathogenesis such as diabetic retinopathy and glaucoma. In addition, the retrobulbar circulation that feeds the choroid shows an important pathophysiologic role in myopia and degenerative myopia. Owing to the light-absorbing retinal pigment epithelium (RPE) and optically opaque sclera, choroidal and retrobulbar vasculature were difficult to be observed using clinically accepted optical coherence tomography angiography (OCT-A) technique. Here, we have developed super-resolution ultrasound microvessel imaging technique to visualize the deep ocular vasculature.MethodsAn 18-MHz linear array transducer with compounding plane wave imaging technique and contrast agent - microbubble was implemented in this study. The centroid intensity of each microbubble was detected using image deconvolution algorithm with spatially variant point spread function, and then accumulated in successive frames in order to reconstruct microvasculature. The image deconvolution technique was first evaluated in a simulation study and experimental flow phantoms. The performance was then validated on normal rabbit eyes in vivo.ResultsThe image deconvolution based super-resolution ultrasound microvessel imaging technique shows good performance on either simulation study or flow phantoms. In vivo rabbit eye study indicated that the micron-level choroidal and retrobulbar vessels around the optic nerve head were successfully reconstructed in multiple 2D views and 3D volume imaging.ConclusionsOur results demonstrate the capability of using super-resolution ultrasound microvessel imaging technique to image the microvasculature of the posterior pole of the eye. This efficient approach can potentially lead to a routinely performed diagnostic procedure in the field of ophthalmology.
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Project description:Micro-computed tomography (micro-CT) is used in pre-clinical research to generate high-resolution three-dimensional (3D) images of organs and tissues. When combined with intravascular contrast agents, micro-CT can provide 3D visualization and quantification of vascular networks in many different organs. However, the lungs present a particular challenge for contrast perfusion due to the complexity and fragile nature of the lung microcirculation. The protocol described here has been optimized to achieve consistent lung perfusion of the microvasculature to vessels < 20 microns in both normal and pulmonary arterial hypertension rats. High-resolution 3D micro-CT imaging can be used to better visualize changes in 3D architecture of the lung microcirculation in pulmonary vascular disease and to assess the impact of therapeutic strategies on microvascular structure in animal models of pulmonary arterial hypertension.
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Project description:IntroductionThe assessment of thrombus size following treatments directed at preventing thrombosis or enhancing its resolution has generally relied on physical or histological methods. This cross-sectional design imposes the need for increased numbers of animals for experiments. Micro-computed tomography (microCT) has been used to detect the presence of venous thrombus in experimental models but has yet to be used in a quantitative manner. In this study, we investigate the use of contrast-enhanced microCT for the longitudinal assessment of experimental venous thrombus resolution.Materials and methodsThrombi induced by stenosis of the inferior vena cava in mice were imaged by contrast-enhanced microCT at 1, 7 and 14 days post-induction (n=18). Thrombus volumes were determined longitudinally by segmentation and 3D volume reconstruction of microCT scans and by standard end-point histological analysis at day 14. An additional group of thrombi were analysed solely by histology at 1, 7 and 14 days post-induction (n=15).ResultsIVC resident thrombus was readily detectable by contrast-enhanced microCT. MicroCT-derived measurements of thrombus volume correlated well with time-matched histological analyses (ICC=0.75, P<0.01). Thrombus volumes measured by microCT were significantly greater than those derived from histological analysis (P<0.001). Intra- and inter-observer analyses were highly correlated (ICC=0.99 and 0.91 respectively, P<0.0001). Further histological analysis revealed noticeable levels of contrast agent extravasation into the thrombus that was associated with the presence of neovascular channels, macrophages and intracellular iron deposits.ConclusionContrast-enhanced microCT represents a reliable and reproducible method for the longitudinal assessment of venous thrombus resolution providing powerful paired data.
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Project description:Understanding of normal fetal organ development is crucial for the evaluation of the pathogenesis of congenital anomalies. Various techniques have been used to generate imaging of fetal rat organogenesis, such as histological dissection with 3-dimensional reconstruction and scanning electron microscopy. However, these techniques did not imply quantitative measurements of developing organs (volumes, surface areas of organs). Furthermore, a partial or total destruction of the embryos prior to analysis was inevitable. Recently, micro-computed tomography (micro-CT) has been established as a novel tool to investigate embryonic development in non-dissected embryos of rodents. In this study, we used the micro-CT technique to generate 4D datasets of rat embryos aged between embryonic day 15-22 and newborns. Lungs, hearts, diaphragms, and livers were digitally segmented in order to measure organ volumes and analyze organ development as well as generate high-resolution 3D images. These data provide objective values compiling a 4D atlas of pulmonary, cardiac, diaphragmatic, and hepatic development in the fetal rat.
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Project description:Vascular exploration of small animals requires imaging hardware with a very high spatial resolution, capable of differentiating large as well as small vessels, in both in vivo and ex vivo studies. Micro Computed Tomography (micro-CT) has emerged in recent years as the preferred modality for this purpose, providing high resolution 3D volumetric data suitable for analysis, quantification, validation, and visualization of results. The usefulness of micro-CT, however, can be adversely affected by a range of factors including physical animal preparation, numerical quantification, visualization of results, and quantification software with limited possibilities. Exacerbating these inherent difficulties is the lack of a unified standard for micro-CT imaging. Most micro-CT today is aimed at particular applications and the software tools needed for quantification, developed mainly by imaging hardware manufacturers, lack the level of detail needed to address more specific aims. This review highlights the capabilities of micro-CT for vascular exploration, describes the current state of imaging protocols, and offers guidelines and suggestions aimed at making micro-CT more accurate, replicable, and robust.
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Project description:We sought to determine how the individual components of the distal esophagus and proximal stomach form the gastroesophageal junction high-pressure zone (GEJHPZ) antireflux barrier.An endoscopic ultrasound/manometry catheter was pulled through the proximal stomach and distal esophagus in 20 normal subjects. The axial length and width of individual structures on endoscopic ultrasound were measured. The anatomic orientation of gastroesophageal junction (GEJ) components was examined in two organ donor specimens using micro-computed tomography (micro-CT).The three distinct structures identified within the GEJHPZ, from distal to proximal, were as follows: the gastric clasp and sling muscle fiber complex, crural diaphragm, and lower esophageal circular smooth muscle fibers (LEC). The LEC was statistically significantly thicker than adjacent esophageal muscles. These structures were associated with three pressure peaks. The pressure peak produced by the clasp/sling fiber complex often overlapped with the pressure peak from the crural diaphragm. The most proximal peak, associated with the LEC, was significantly greater and bimodal in nine of 20 subjects. This bimodal LEC pressure peak correlated with two areas of thickened muscle observed with ultrasound. Micro-CT of GEJ from organ donors confirmed the two areas of thickened muscle.Three distinct anatomic structures, the clasp and sling muscle fibers, crural diaphragm, and LEC combine to form the antireflux barrier of the proximal stomach and distal esophagus. The clasp and sling muscle fibers combine with the crural diaphragm to form a distal pressure profile. The more proximal LEC has a bimodal pressure profile in some patients.
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Project description:Osteoarthritis causes changes in the subchondral bone structure and composition. Plain radiography is a cheap, fast, and widely available imaging method. Bone tissue can be well seen from plain radiograph, which however is only a 2D projection of the actual 3D structure. Therefore, the aim was to investigate the relationship between bone density- and structure-related parameters from 2D plain radiograph and 3D bone parameters assessed from micro computed tomography (µCT) ex vivo. Right tibiae from eleven cadavers without any diagnosed joint disease were imaged using radiography and with µCT. Bone density- and structure-related parameters were calculated from four different locations from the radiographs of proximal tibia and compared with the volumetric bone microarchitecture from the corresponding regions. Bone density from the plain radiograph was significantly related with the bone volume fraction (r = 0.86; n = 44; p < 0.01). Mean homogeneity index for orientation of local binary patterns (HI(angle,mean)) and fractal dimension of vertical structures (FD(Ver)) were related (p < 0.01) with connectivity density (HI(angle,mean): r = -0.73, FD(Ver): r = 0.69) and trabecular separation (HI(angle,mean): r = 0.73, FD(Ver): r = -0.70) when all ROIs were pooled together (n = 44). Bone density and structure in tibia from standard clinically available 2D radiographs are significantly correlated with true 3D microstructure of bone.
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Project description:Continuous improvements in the resolution of three-dimensional imaging have led to an increased application of these techniques in conventional taxonomic research in recent years. Coupled with an ever increasing research effort in cybertaxonomy, three-dimensional imaging could give a boost to the development of virtual specimen collections, allowing rapid and simultaneous access to accurate virtual representations of type material. This paper explores the potential of micro-computed tomography (X-ray micro-tomography), a non-destructive three-dimensional imaging technique based on mapping X-ray attenuation in the scanned object, for supporting research in systematics and taxonomy. The subsequent use of these data as virtual type material, so-called "cybertypes", and the creation of virtual collections lie at the core of this potential. Sample preparation, image acquisition, data processing and presentation of results are demonstrated using polychaetes (bristle worms), a representative taxon of macro-invertebrates, as a study object. Effects of the technique on the morphological, anatomical and molecular identity of the specimens are investigated. The paper evaluates the results and discusses the potential and the limitations of the technique for creating cybertypes. It also discusses the challenges that the community might face to establish virtual collections. Potential future applications of three-dimensional information in taxonomic research are outlined, including an outlook to new ways of producing, disseminating and publishing taxonomic information.
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Project description:This study used available or purchased equipment and an image reconstruction system developed by the college of dentistry to establish a basic self-assembled micro-computed tomography (micro-CT) system. Such a system would be suitable for teaching dental radiology to dental students. Specifically, it could help students to understand the principles governing dental cone-beam computed tomography (CBCT) and provide graduate students with a system for scanning small samples (e.g., individual teeth) during the early stages of research. The self-assembled micro-CT system was constructed using a portable dental X-ray tube, an intraoral digital X-ray detector, a high-precision rotation stage, related bracket accessories, and a notebook computer. Reconstructed images and three-dimensional models of the maxillary right third molar were produced using the self-assembled micro-CT system and an advanced commercially available micro-CT system (Skyscan 2211). Subsequently, the reconstructed images and 3D models produced using the two systems were compared by two senior dentists to determine whether considerable visual differences could be observed. Finally, the signal-to-noise ratio (SNR) was used for quantitative analysis and to compare the systems. Although the self-assembled micro-CT system produced image boundaries that were not as sharp as those of Skyscan 2211, the images were nonetheless remarkably similar. In addition, the two micro-CT systems produced 3D models that were almost identical in appearance and root canal shape. Quantitative analysis revealed that Skyscan 2211 had produced a SNR that was superior to that of the self-assembled micro-CT system, with the difference ranging from 36.77% to 136.22%; enamel, which has a higher density, exhibited lower SNR differences, whereas dentin, which has a lower density, exhibited higher SNR differences. The self-assembled micro-CT system with a resolution of 36 μm was created using a portable dental X-ray tube and an intraoral digital X-ray detector. Although the scanning time was relatively long (~30 min to scan images of a tooth), the images were adequate in the preliminary stage of experiments. More importantly, students were afforded the opportunity to observe the process of assembling and disassembling each component of a micro-CT scanner and thereby achieve a more comprehensive understanding of the principles governing micro-CT and dental CBCT.
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