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Françoise Peyrin - One of the best experts on this subject based on the ideXlab platform.
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Assessment of the human bone lacuno-canalicular network at the nanoscale and impact of spatial resolution
Scientific Reports, 2020Co-Authors: Alexandra Pacureanu, Cecile Olivier, Peter Cloetens, Françoise PeyrinAbstract:Recently, increasing attention has been given to the study of osteocytes, the cells that are thought to play an important role in bone remodeling and in the mechanisms of bone fragility. The interconnected osteocyte system is deeply embedded inside the mineralized bone matrix and lies within a closely fitted porosity known as the lacuno-canalicular network. However, quantitative data on human samples remain scarce, mostly measured in 2D, and there are gaps to be filled in terms of spatial resolution. In this work, we present data on femoral samples from female donors imaged with isotropic 3D spatial resolution by magnified X-ray phase nano computerized-tomography. We report quantitative results on the 3D structure of canaliculi in human femoral bone imaged with a voxel size of 30 nm. We found that the lacuno-canalicular porosity occupies on average 1.45% of the total tissue volume, the ratio of the canalicular versus lacunar porosity is about 37.7%, and the primary number of canaliculi stemming from each lacuna is 79 on average. The examination of this number at different distances from the surface of the lacunae demonstrates branching in the canaliculi network. We analyzed the impact of spatial resolution on quantification by comparing parameters extracted from the same samples imaged with 120 nm and 30 nm voxel sizes. To avoid any bias related to the analysis region, the volumes at 120 nm and 30 nm were registered and cropped to the same field of view. Our results show that the measurements at 120 and 30 nm are strongly correlated in our data set but that the highest spatial resolution provides more accurate information on the canaliculi network and its branching properties.
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Assessment of the lacuno-canalicular network in human bone from magnified phase nano-CT images
2017Co-Authors: Max Langer, Cecile Olivier, Alexandra Pacureanu, Pierre-jean Gouttenoire, Peter Cloetens, Françoise PeyrinAbstract:The osteocyte system, which plays a major role in the triggering of bone remodeling, has recently attracted increasing attentions but its properties in association to bone fragility are still unclear. It is residing the lacuno-canalicular network (LCN) which appears as a complex mesh where lacunae serve as nodes connected with each other by many small channels (canaliculi). Since it is deeply embedded inside bone tissue, the 3D analysis of the LCN at high spatial resolution is still challenging, although a number of 3D imaging techniques have recently been proposed. Here, we propose to use X-ray magnified phase nano-CT (nCT) to extract quantitative information about the LCN in human bone. Small samples were cut from cross sections of the mid-diaphysis of the left femur of 4 women cadavers (ages 56 - 95 years old). Imaging experiments were performed at the beamline ID16A of the European Synchrotron Radiation Facility (ESRF), Grenoble. For each samples, phase contrast CT scans were acquired at four different propagation distances, at voxels sizes of 120 and 30nm. After phase retrieval and tomographic reconstruction, the lacunae and canaliculi were segmented from the volumes at 120nm, by the hysteresis thresholding algorithm and a dedicated 3D minimal path method respectively. Due to the large nCT data sets (32 GB/ (2048)3 image), the computations for the canaliculi segmentation were parallelized on a cluster of computers. Quantitative parameters could then be calculated from the binary images. Table 1 presents lacunae parameters including the lacuna porosity, density as well as morphological parameters. The development of image analysis methods for the images at 30nm is in progress. This work is expected to bring new characteristics of the LCN in three dimensions at the nano scale which will be correlated to biomechanical parameters measured on the same subjects.
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3D osteocyte lacunar morphometric properties and distributions in human femoral cortical bone using synchrotron radiation micro-CT images
BONE, 2015Co-Authors: P. Dong, P.-J. Gouttenoire, Valérie Bousson, M Langer, Sylvain Haupert, B Hesse, Françoise PeyrinAbstract:Osteocytes, the most numerous bone cells, are thought to be actively involved in the bone modeling and remodeling processes. The morphology of osteocyte is hypothesized to adapt according to the physiological mechanical loading. Three-dimensional micro-CT has recently been used to study osteocyte lacunae. In this work, we proposed a computationally efficient and validated automated image analysis method to quantify the 3D shape descriptors of osteocyte lacunae and their distribution in human femurs. Thirteen samples were imaged using Synchrotron Radiation (SR) micro-CT at ID19 of the ESRF with 1.4μm isotropic voxel resolution. With a field of view of about 2.9×2.9×1.4mm3, the 3D images include several tens of thousands of osteocyte lacunae. We designed an automated quantification method to segment and extract 3D cell descriptors from osteocyte lacunae. An image moment-based approach was used to calculate the volume, length, width, height and anisotropy of each osteocyte lacuna. We employed a fast algorithm to further efficiently calculate the surface area, the Euler number and the structure model index (SMI) of each lacuna. We also introduced the 3D lacunar density map to directly visualize the lacunar density variation over a large field of view. We reported the lacunar morphometric properties and distributions as well as cortical bone histomorphometric indices on the 13 bone samples. The mean volume and surface were found to be 409.5±149.7μm3 and 336.2±94.5μm2. The average dimensions were of 18.9±4.9μm in length, 9.2±2.1μm in width and 4.8±1.1μm in depth. We found lacunar number density and six osteocyte lacunar descriptors, three axis lengths, two anisotropy ratios and SMI, that are significantly correlated to bone porosity at a same local region. The proposed method allowed an automatic and efficient direct 3D analysis of a large population of bone cells and is expected to provide reliable biological information for better understanding the bone quality and diseases at cellular level.
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3D Synchrotron Imaging of Bone Tissue : from micro to cellular scale
2015Co-Authors: Françoise PeyrinAbstract:The osteocyte system located within the lacuno-canalicular network (LCN) is playing a key role in the mechanobiology of bone. Synchrotron Radiation (SR) micro-CT was recently used in a number of studies to characterize osteocyte lacunae. Nevertheless, few works are reporting three-dimensional properties of both osteocyte lacunae and canaliculi. Here, we show that SR nano-CT can be used either for a global assessment of the LCN in entire osteons or a detailed analysis around a few cells. We used SR parallel-beam micro-CT at beamline ID19 at the European Synchrotron Radiation Facility (ESRF) to image the LCN [1]. With a nominal voxel size of 280nm, this technique provides images of the LCN within a cubic FOV of side 600μm, including over hundreds of cells in one or several osteons. We developed a framework to extract statistical information about the lacunae and on the number of canaliculi issued from each lacuna. Due to the limited spatial resolution of the image compared to the canaliculi diameter, the segmentation of the LCN is the most challenging part of the analysis and new solutions were investigated. This method was applied to the analysis of human femoral cortical bone samples. The mean and standard deviation of lacunar volume was 216.44 ± 84.7 μm3 and their average lengths were respectively 15.2, 7.8 and 4.0, with a length ratio about 4:2:1. The average distance between lacunae was found to be 23.2 μm. The average number of canaliculi per lacuna was found to increase between 36.9 and 108.6 with the distance from the lacunae. The mean of the average length of the primary canaliculi was about 6.4 μm. SR magnified phase CT at the nano scale (voxel size : 60 nm) was used to image the LCN on more restricted FOV (side ~ 120 μm) at beamline ID22, ESRF [2]. This technique provides a detailed rendering of the LCN architecture including the organization of canaliculi around the lacunae, an assessment of the local degree of mineralization of bone, as well as information about the 3D organization of the collagen fibers. The imaging techniques developed here are likely to provide a better understanding of the role of the 3D geometry of the LCN on biomechanical strain and stress at the nano scale level. [1] Pacureanu A, Langer M, Boller E, Tafforeau P, Peyrin F. Med Phys 2012;39:2229. [2] Langer M, Pacureanu A, Suhonen H, Grimal Q, Cloetens P, Peyrin F. PLoS ONE 2012;7:e35691.
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Voronoi-based analysis of bone cell network from synchrotron radiation micro-CT images
2015Co-Authors: P. Dong, Maria A. Zuluaga, J. Kazakia G., Sébastien Valette, Françoise PeyrinAbstract:With the development of the novel micro and nano-CT systems, bone cell analysis has gone beyond the limitation of the conventional 2D analysis. In particular synchrotron radiation micro-CT is well suited to image in 3D the lacuno-canalicular network (LCN) in bone tissue. This network is made of osteocyte lacunae connected by small channels called canaliculi. Due to the lack of quantitative data on this network, we propose here an automated method to extract geodesic Voronoi-based parameters to characterize the regions of influence of canaliculi. To this aim, after labeling each lacuna from the segmented LCN image, we generated geodesic Voronoi tessellations on each lacunar surface. Our proposed method was successfully applied to three SR micro-CT images of women tibial cortical samples. We believe that this method can serve to extract new information on the 3D morphometry of the LCN in more datasets.
Jonathan Rosand - One of the best experts on this subject based on the ideXlab platform.
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distribution of Lacunes in cerebral amyloid angiopathy and hypertensive small vessel disease
Neurology, 2017Co-Authors: Marco Pasi, Gregoire Boulouis, Panagiotis Fotiadis, Andreas Charidimou, Eitan Auriel, Alison M. Ayres, Kristin Schwab, Joshua N. Goldstein, Kellen Haley, Jonathan RosandAbstract:Objective: To evaluate whether the burden of deep and lobar Lacunes differs between patients with intracerebral hemorrhage (ICH) with definite/probable cerebral amyloid angiopathy (CAA) per the Boston criteria and hypertensive small vessel disease (HTN-SVD; ICH in basal ganglia, thalami, brainstem). Methods: We defined lobar and deep Lacunes similar to the topographic distribution used for ICH and cerebral microbleeds (CMBs). We then compared their distribution between patients with CAA-ICH and those with strictly deep CMB and ICH (HTN-ICH). The independent associations of Lacune location with the diagnosis of CAA-ICH and HTN-ICH were evaluated with multivariable models. The relationship between lobar Lacunes and white matter hyperintensity (WMH) volume was evaluated by means of partial correlation analyses adjusted for age and a validated visual scale. Results: In our final cohort of 316 patients with ICH, Lacunes were frequent (24.7%), with similar rates in 191 patients with CAA and 125 with HTN-ICH (23% vs 27.2%, p = 0.4). Lobar Lacunes were more commonly present in CAA (20.4% vs 5.7%, p p p = 0.003) and deep Lacunes with HTN-ICH ( p r = 0.42, p Conclusions: Lobar Lacunes are associated with CAA, whereas deep Lacunes are more frequent in HTN-SVD. Lobar Lacunes seem to have a close relationship with WMH, suggesting a possible common origin.
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Abstract WMP100: Topographical Distribution of Lacunes in Cerebral Amyloid Angiopathy and Deep Hypertensive Intracerebral Hemorrhage
Stroke, 2017Co-Authors: Marco Pasi, Gregoire Boulouis, Panagiotis Fotiadis, Andreas Charidimou, Eitan Auriel, Kellen Aley, Alison M. Ayres, Kristin Schwab, Joshua N. Goldstein, Jonathan RosandAbstract:Background/Aims: To evaluate whether the burden of Lacunes located at deep and lobar brain regions, would differ between intracerebral hemorrhage patients (ICH) with cerebral amyloid angiopathy (CAA) vs patients with strictly deep cerebral microbleeds (CMB) and ICH (Deep HTN-ICH). Methods: We defined lobar and deep Lacunes similar to the topographic distribution used for ICH and microbleeds. We then compared their distribution between CAA and Deep HTN-ICH patients. The independent associations of Lacune location (lobar vs deep) with diagnosis of CAA-ICH and Deep HTN-ICH were evaluated using multivariable models. The relationship between lobar and deep Lacunes and WMH volume was evaluated using partial correlation analyses adjusting for age and by means of a validated visual scale. Results: In our cohort of 316 ICH patients, lobar Lacunes were more commonly present in CAA (20.4% vs 5.7% in Deep HTN-ICH, p r=0.52, p Conclusions: Lobar Lacunes are associated with CAA whereas deep Lacunes are more frequent in patients with Strictly deep CMBs and ICH, they can thus be clinically useful in the appropriate context. Lobar Lacunes seem to have a close relationship with WMH suggesting a possible common origin.
Joanna M. Wardlaw - One of the best experts on this subject based on the ideXlab platform.
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What Is a Lacune
Stroke, 2008Co-Authors: Joanna M. WardlawAbstract:See related article, pages 3083–3085. The terms “Lacune”, “lacunar infarct” and “lacunar stroke” are often used interchangeably, but they are not the same thing. Lacunes are 3 to 15 mm cerebrospinal fluid (CSF)-filled cavities in the basal ganglia or white matter, frequently observed coincidentally on imaging in older people, often not clearly associated with discrete neurological symptoms. “Lacunar stroke” describes a clinical stroke syndrome with the typical symptoms and signs referable to a small subcortical or brain stem lesion.1,2 “Lacunar infarct” should refer to a clinical stroke syndrome of lacunar type where the underlying lesion is an infarct on brain-imaging. On CT or MR T2-weighted and fluid-attenuated inversion recovery (FLAIR) imaging, an acute lacunar infarct can look just like a white matter lesion (WML), difficult to distinguish from an asymptomatic WML without diffusion-imaging to show a hyperintense signal (reduced on ADC), or a prior scan for comparison, especially in patients with WMLs. Some clinically evident acute lacunar infarcts may evolve with time into Lacunes. These points are well-established. Less well-established is how many clinically evident lacunar infarcts ever cavitate to become “Lacunes”. It seems generally assumed that all Lacunes start life as an infarct, even if the patient did not notice anything, and therefore share the same risk factors, etiology, prognosis, pathogenesis, etc, as clinically evident lacunar infarcts.3–5 However, suppose only a proportion of lacunar …
Zhendong Liu - One of the best experts on this subject based on the ideXlab platform.
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low carotid endothelial shear stress associated with cerebral small vessel disease in an older population a subgroup analysis of a population based prospective cohort study
Atherosclerosis, 2019Co-Authors: Yali Chen, Jizheng Zhu, Hua Zhang, Yingxin Zhao, Yuanli Dong, Yi Cui, Gary Gong, Qiang Chai, Yuqi Guo, Zhendong LiuAbstract:Abstract Background and aims The association between carotid wall shear stress (WSS) and cerebral small vessel disease has yet to be fully elucidated. The major purpose of this study was to investigate this association in older subjects. Methods Common carotid artery WSS, endothelial function, white matter hyperintensities (WMH), Lacunes, and microbleeds were assessed in 1396 older adults. Participants were followed-up for an average of 69.7 months. Results Mean (M) and peak (P) WSS and changes in endothelial function were independently associated with changes in WMH volume and fraction, Lacune counts, and microbleed counts (all p p = 0.005 and 1.731 (1.197–2.505), p = 0.004, respectively], Lacunes [HR (95% CI): 2.034 (1.369–3.022), p p = 0.003, respectively], and microbleeds [HR (95% CI): 2.311 (1.509–3.541), p p Conclusions Low carotid WSS is an independent risk factor for the progression of cerebral small vessel disease in older adults.
Hugh S. Markus - One of the best experts on this subject based on the ideXlab platform.
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Strategic Lacunes and their relationship to cognitive impairment in cerebral small vessel disease
NeuroImage. Clinical, 2014Co-Authors: Philip Benjamin, Andrew J. Lawrence, Christian Lambert, Bhavini Patel, Ai Wern Chung, Andrew D. Mackinnon, Robin G. Morris, Thomas R. Barrick, Hugh S. MarkusAbstract:Objectives Lacunes are an important disease feature of cerebral small vessel disease (SVD) but their relationship to cognitive impairment is not fully understood. To investigate this we determined (1) the relationship between Lacune count and total Lacune volume with cognition, (2) the spatial distribution of Lacunes and the cognitive impact of Lacune location, and (3) the whole brain anatomical covariance associated with these strategically located regions of Lacune damage.
