Simultaneous 3D Visualization of the Microvascular and Neural Network in Mouse Spinal Cord Using Synchrotron Radiation Micro-Computed Tomography.
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ABSTRACT:
SUBMITTER: Jiang L
PROVIDER: S-EPMC8490558 | biostudies-literature |
REPOSITORIES: biostudies-literature
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Project description:Precise assessment of spinal cord cystic lesions is crucial to formulate effective therapeutic strategies, yet histological assessment of the lesion remains the primary method despite numerous studies showing inconsistent results regarding estimation of lesion size via histology. On the other hand, despite numerous advances in micro-computed tomography (micro-CT) imaging and analysis that have allowed precise measurements of lesion size, there is not enough published data on its application to estimate intraspinal lesion size in laboratory animal models. This work attempts to show that micro-CT can be valuable for spinal cord injury research by demonstrating accurate estimation of syrinx size and compares between micro-CT and traditional histological analysis. We used a post-traumatic syringomyelia rat model to compare micro-CT analysis to conventional histological analysis. The study showed that micro-CT can detect lesions within the spinal cord very similar to histology. Importantly, micro-CT appears to provide more accurate estimates of the lesions with more measures (e.g., surface area), can detect compounds within the cord, and can be done with the tissue of interest (spinal cord) intact. In summary, the experimental work presented here provides one of the first investigations of the use of micro-CT for estimating the size of intraparenchymal cysts and detecting materials within the spinal cord. All animal procedures were approved by the University of Akron Institutional Animal Care and Use Committee (IACUC) (protocol # LRE 16-05-09 approved on May 14, 2016).
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Project description:Comparative anatomy is an important tool for investigating evolutionary relationships among species, but the lack of scalable imaging tools and stains for rapidly mapping the microscale anatomies of related species poses a major impediment to using comparative anatomy approaches for identifying evolutionary adaptations. We describe a method using synchrotron source micro-x-ray computed tomography (syn-μXCT) combined with machine learning algorithms for high-throughput imaging of Lepidoptera (i.e., butterfly and moth) eyes. Our pipeline allows for imaging at rates of ~15 min/mm3 at 600 nm3 resolution. Image contrast is generated using standard electron microscopy labeling approaches (e.g., osmium tetroxide) that unbiasedly labels all cellular membranes in a species-independent manner thus removing any barrier to imaging any species of interest. To demonstrate the power of the method, we analyzed the 3D morphologies of butterfly crystalline cones, a part of the visual system associated with acuity and sensitivity and found significant variation within six butterfly individuals. Despite this variation, a classic measure of optimization, the ratio of interommatidial angle to resolving power of ommatidia, largely agrees with early work on eye geometry across species. We show that this method can successfully be used to determine compound eye organization and crystalline cone morphology. Our novel pipeline provides for fast, scalable visualization and analysis of eye anatomies that can be applied to any arthropod species, enabling new questions about evolutionary adaptations of compound eyes and beyond.
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Project description:Up to 40% of congenital diseases present disturbances of brain and craniofacial development resulting in simultaneous alterations of both systems. Currently, the best available method to preclinically visualize the brain and the bones simultaneously is to co-register micro-magnetic resonance (µMR) and micro-computed tomography (µCT) scans of the same specimen. However, this requires expertise and access to both imaging techniques, dedicated software and post-processing knowhow. To provide a more affordable, reliable and accessible alternative, recent research has focused on optimizing a contrast-enhanced µCT protocol using iodine as contrast agent that delivers brain and bone images from a single scan. However, the available methods still cannot provide the complete visualization of both the brain and whole craniofacial complex. In this study, we have established an optimized protocol to diffuse the contrast into the brain that allows visualizing the brain parenchyma and the complete craniofacial structure in a single ex vivo µCT scan (whiceCT). In addition, we have developed a new technique that allows visualizing the brain ventricles using a bilateral stereotactic injection of iodine-based contrast (viceCT). Finally, we have tested both techniques in a mouse model of Down syndrome, as it is a neurodevelopmental disorder with craniofacial, brain and ventricle defects. The combined use of viceCT and whiceCT provides a complete visualization of the brain and bones with intact craniofacial structure of an adult mouse ex vivo using a single imaging modality.
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Project description:PurposeSpinal cord delineation is critical to the delivery of stereotactic body radiation therapy (SBRT). Although underestimating the spinal cord can lead to irreversible myelopathy, overestimating the spinal cord may compromise the planning target volume coverage. We compare spinal cord contours based on computed tomography (CT) simulation with a myelogram to spinal cord contours based on fused axial T2 magnetic resonance imaging (MRI).Methods and materialsEight patients with 9 spinal metastases treated with spinal SBRT were contoured by 8 radiation oncologists, neurosurgeons, and physicists, with spinal cord definition based on (1) fused axial T2 MRI and (2) CT-myelogram simulation images, yielding 72 sets of spinal cord contours. The spinal cord volume was contoured at the target vertebral body volume based on both images. The mixed-effect model assessed comparisons of T2 MRI- to myelogram-defined spinal cord in centroid deviations (deviations in the center point of the cord) through the vertebral body target volume, spinal cord volumes, and maximum doses (0.035 cc point) to the spinal cord applying the patient's SBRT treatment plan, in addition to in-between and within-subject variabilities.ResultsThe estimate for the fixed effect from the mixed model showed that the mean difference between 72 CT volumes and 72 MRI volumes was 0.06 cc and was not statistically significant (95% confidence interval, -0.034, 0.153; P = .1832). The mixed model showed that the mean dose at 0.035 cc for CT-defined spinal cord contours was 1.24 Gy lower than that of MRI-defined spinal cord contours and was statistically significant (95% confidence interval, -2.292, -0.180; P = .0271). Also, the mixed model indicated no statistical significance for deviations in any of the axes between MRI-defined spinal cord contours and CT-defined spinal cord contours.ConclusionsCT myelogram may not be required when MRI imaging is feasible, although uncertainty at the cord-to-treatment volume interface may result in overcontouring and hence higher estimated cord dose-maximums with axial T2 MRI-based cord definition.
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Project description:Micro-computed tomography (CT) is an X-ray-based imaging modality that produces three-dimensional (3D), high-resolution images of whole-mount tissues, but is typically limited to dense tissues, such as bone. The X-rays readily pass-through tendons, rendering them transparent. Contrast-enhancing chemical stains have been explored, but their use to improve contrast in different tendon types and across developmental stages for micro-CT imaging has not been systematically evaluated. Therefore, we investigated how phosphotungstic acid (PTA) staining and tissue hydration impacts tendon contrast for micro-CT imaging. We showed that PTA staining increased X-ray absorption of tendon to enhance tissue contrast and obtain 3D micro-CT images of immature (postnatal day 21) and sexually mature (postnatal day 50) rat tendons within the tail and hindlimb. Further, we demonstrated that tissue hydration state following PTA staining significantly impacts soft tissue contrast. Using this method, we also found that tail tendon fascicles appear to cross between fascicle bundles. Ultimately, contrast-enhanced 3D micro-CT imaging will lead to better understanding of tendon structure, and relationships between the bone and soft tissues.•Simple tissue fixation and staining technique enhances soft tissue contrast for tendon visualization using micro-CT.•3D tendon visualization in situ advances understanding of musculoskeletal tissue structure and organization.
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Project description:ImportanceThere is no imaging standard to model nasal cartilage for the planning of rhinoplasty procedures. Preoperative visualization of cartilage may improve objective evaluation of nasal deformities, surgical planning, and surgical reconstruction.ObjectivesTo evaluate the feasibility of visualizing nasal cartilage using high resolution micro-computed tomography (CT) compared with the criterion standard of pathologic findings in a cadaveric specimen and to evaluate its accuracy compared with various clinical CT protocols.Design, setting, and participantsAnatomic study at the University of Washington using single human cadaveric nasal specimens performed from July 10, 2017, to March 30, 2018.InterventionsA micro-CT acquisition with 60-micron resolution was obtained of a nasal specimen. The specimen was then scanned with 5 different clinical CT protocols to span both clinical care and machine limits. The specimen was then sectioned in 5-mm axial slices for pathologic analysis.Main outcomes and measuresMicro-CT images were registered to pathologic specimen cross-sections using a graphite fiducial system. Cartilage substructures were manually segmented and analyzed. A library of matched images across the micro-CT and various clinical CT protocols was then developed. Region of interest analysis was performed for each of the cartilage structures and their boundaries on clinical CT protocols and micro-CT, with the outcome of mean (SD) density using Hounsfield units.ResultsA single human cadaveric nasal specimen was used to obtain the following results. Lower lateral cartilage, upper lateral cartilage, and septal cartilage were accurately delineated on the micro-CT images compared with pathologic findings. The mean absolute deviation from pathologic findings was 0.30 mm for septal cartilage thickness, 0.98 mm for maximal upper lateral cartilage length, and 1.40 mm for maximal lower lateral cartilage length. On clinical CT protocols, only septal cartilage was well discriminated from boundary. Higher radiation dose resulted in more accurate density measurements of cartilage, but it did not ultimately improve ability to discriminate cartilage.Conclusions and relevanceThe results of this anatomic study may represent a notable step toward advancing knowledge of the capabilities and pitfalls of nasal cartilage visualization on CT. Nasal cartilage visualization was feasible on the micro-CT compared with pathologic findings. Future research may further examine the barriers to accurately visualizing upper lateral cartilage and lower lateral cartilage, a prerequisite for clinical application.Level of evidenceNA.
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Project description:IntroductionThe mechanisms of lung inflation and deflation are only partially known. Ventilatory strategies to support lung function rely upon the idea that lung alveoli are isotropic balloons that progressively inflate or deflate and that lung pressure/volume curves derive only by the interplay of critical opening pressures, critical closing pressures, lung history, and position of alveoli inside the lung. This notion has been recently challenged by subpleural microscopy, magnetic resonance, and computed tomography (CT). Phase-contrast synchrotron radiation CT (PC-SRCT) can yield in vivo images at resolutions higher than conventional CT.ObjectivesWe aimed to assess the numerosity (ASden) and the extension of the surface of airspaces (ASext) in healthy conditions at different volumes, during stepwise lung deflation, in concentric regions of the lung.MethodsThe study was conducted in seven anesthetized New Zealand rabbits. They underwent PC-SRCT scans (resolution of 47.7 μm) of the lung at five decreasing positive end expiratory pressure (PEEP) levels of 12, 9, 6, 3, and 0 cmH2O during end-expiratory holds. Three concentric regions of interest (ROIs) of the lung were studied: subpleural, mantellar, and core. The images were enhanced by phase contrast algorithms. ASden and ASext were computed by using the Image Processing Toolbox for MatLab. Statistical tests were used to assess any significant difference determined by PEEP or ROI on ASden and ASext.ResultsWhen reducing PEEP, in each ROI the ASden significantly decreased. Conversely, ASext variation was not significant except for the core ROI. In the latter, the angular coefficient of the regression line was significantly low.ConclusionThe main mechanism behind the decrease in lung volume at PEEP reduction is derecruitment. In our study involving lung regions laying on isogravitational planes and thus equally influenced by gravitational forces, airspace numerosity and extension of surface depend on the local mechanical properties of the lung.
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Project description:Although the topic of tooth fractures has been extensively analyzed in the dental literature, there is still insufficient information about the potential effect of enamel microcracks (EMCs) on the underlying tooth structures. For a precise examination of the extent of the damage to the tooth structure in the area of EMCs, it is necessary to carry out their volumetric [(three-dimensional (3D)] evaluation. The aim of this study was to validate an X-ray micro-computed tomography ([Formula: see text]CT) as a technique suitable for 3D non-destructive visualization and qualitative analysis of teeth EMCs of different severity. Extracted human maxillary premolars were examined using a [Formula: see text]CT instrument ZEISS Xradia 520 Versa. In order to separate crack, dentin, and enamel volumes a Deep Learning (DL) algorithm, part of the Dragonfly's segmentation toolkit, was utilized. For segmentation needs we implemented Dragonfly's pre-built UNet neural network. The scanning technique which was used made it possible to recognize and detect not only EMCs that are visible on the outer surface but also those that are buried deep inside the tooth. The 3D visualization, combined with DL assisted segmentation, enabled the evaluation of the dynamics of an EMC and precise examination of its position with respect to the dentin-enamel junction.
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