Characterization of Human Cortical and Trabecular Bone Structural Change by NMR and Micro-CT

2012 ◽  
Author(s):  
Qingwen Ni ◽  
Todd Bredbenner
Keyword(s):  
Trabecular Bone ◽  
Spin Relaxation ◽  
Structural Changes ◽  
Relaxation Times ◽  
Proton Nuclear Magnetic Resonance ◽  
Micro Ct ◽  
Micro Computed Tomography ◽  
T2 Relaxation ◽  
Ct Measurement

The techniques of low-field pulsed proton nuclear magnetic resonance (NMR) spin relaxation and Micro-CT are described for assessment of structural changes of human cortical and trabecular bone in vitro. The technique involves spin-spin relaxation measurement and inversion spin-spin spectral analysis methods for NMR. From NMR measurement, the CPMG T2 relaxation data can be inverted to T2 relaxation distribution and this distribution then can be transformed to a pore size distribution with the longer relaxation times corresponding to larger pores. In Micro-CT measurement, each trabecular bone specimen was individually scanned using a micro-computed tomography (micro-CT) system and 12 micron dimensionally-isotropic voxels were reconstructed. Due to the resolution limitation, Micro-CT measurement on cortical bone was not success, however, NMR measurement was success for both cortical and trabecular bones.

scholarly journals Effect of micro-computed tomography reconstruction protocols on bone fractal dimension analysis

2019 ◽  
Vol 48 (8) ◽  
pp. 20190235
Author(s):  
Hugo Gaêta-Araujo ◽  
Nicolly Oliveira-Santos ◽  
Danieli Moura Brasil ◽  
Eduarda Helena Leandro do Nascimento ◽  
Daniela Verardi Madlum ◽  
...  
Keyword(s):  
Fractal Dimension ◽  
Trabecular Bone ◽  
Micro Ct ◽  
Ct Reconstruction ◽  
Micro Computed Tomography ◽  
Beam Hardening ◽  
Scan Time ◽  
Beam Hardening Correction ◽  
Box Counting Method ◽  
Artefact Correction

Objectives: To evaluate the influence of the level of three micro-CT reconstruction tools: beam-hardening correction (BHC), smoothing filter (SF), and ring artefact correction (RAC) on the fractal dimension (FD) analysis of trabecular bone. Methods: Five Wistar rats’ maxillae were individually scanned in a SkyScan 1174 micro-CT device, under the following settings: 50 kV, 800 µA, 10.2 µm voxel size, 0.5 mm Al filter, rotation step 0.5°, two frames average, 180° rotation and scan time of 35 min. The raw images were reconstructed under the standard protocol (SP) recommended by the manufacturer, a protocol without any artefact correction tools (P0) and 35 additional protocols with different combinations of SF, RAC and BHC levels. The same volume of interest was established in all reconstructions for each maxilla and the FD was calculated using the Kolmogorov (box counting) method. One-way ANOVA with Dunnet’s post-hoc test was used to compare the FD of each reconstruction protocol (P0–P35) with the SP (α = 5%). Multiple linear regression verified the dependency of reconstruction tools in FD. Results: Overall, FD values are not dependent on RAC (p = 0.965), but increased significantly when the level of BHC and SF increased (p < 0.001). FD values from protocols with BHC at 45% combined with SF of 2, and BHC at 30% combined with SF of 4 or 6 had no statistical difference compared to SP. Conclusions: BHC and SF tools affect the FD values of micro-CT images of the trabecular bone. Therefore, these reconstruction parameters should be standardized when the FD is analyzed.

scholarly journals Spatial Correlations of Trabecular Bone Microdamage with Local Stresses and Strains Using Rigid Image Registration

2011 ◽  
Vol 133 (6) ◽  
Author(s):  
Srinidhi Nagaraja ◽  
Oskar Skrinjar ◽  
Robert E. Guldberg
Keyword(s):  
Finite Element ◽  
Image Registration ◽  
Trabecular Bone ◽  
Tissue Level ◽  
Micro Ct ◽  
Micro Computed Tomography ◽  
Element Analysis ◽  
Registration Algorithm ◽  
Local Bone ◽  
Local Stresses

Although microdamage is known to accumulate in trabecular bone with overloading and aging, the tissue-level stresses and strains associated with local bone failure are not well known. Local correlation of microdamage with microstructural stresses and strains requires methods to accurately register histological sections with micro-computed tomography (micro-CT) based finite element models. In addition, the resolution of correlation (i.e., grid size) selected for analysis may affect the observed results. Therefore, an automated, repeatable, and accurate image registration algorithm was developed to determine the range of local stresses and strains associated with microdamage initiation. Using a two-dimensional rigid registration algorithm, bone structures from histology and micro-CT imaging were aligned. Once aligned, microdamaged regions were spatially correlated with local stresses and strains obtained from micro-CT based finite element analysis. Using this more sophisticated registration technique, we were able to analyze the effects of varying spatial grid resolution on local stresses and strains initiating microdamage. The results indicated that grid refinement to the individual pixel level (pixel-by-pixel method) more precisely defined the range of microdamage initiation compared to manually selected individual damaged and undamaged trabeculae. Using the pixel-by-pixel method, we confirmed that trabecular bone from younger cows sustained higher local strains prior to microdamage initiation compared to older bone.

High-Resolution Three-Dimensional-pQCT Images Can Be an Adequate Basis for In-Vivo μFE Analysis of Bone

2000 ◽  
Vol 123 (2) ◽  
pp. 176-183 ◽  
Author(s):  
W. Pistoia ◽  
B. van Rietbergen ◽  
A. Laib ◽  
P. Ru¨egsegger
Keyword(s):  
High Resolution ◽  
Trabecular Bone ◽  
Elastic Properties ◽  
Bone Structure ◽  
Reference Model ◽  
Von Mises Stress ◽  
Micro Ct ◽  
Von Mises

Micro-finite element (μFE) models based on high-resolution images have enabled the calculation of elastic properties of trabecular bone in vitro. Recently, techniques have been developed to image trabecular bone structure in vivo, albeit at a lesser resolution. The present work studies the usefulness of such in-vivo images for μFE analyses, by comparing their μFE results to those of models based on high-resolution micro-CT (μCT) images. Fifteen specimens obtained from human femoral heads were imaged first with a 3D-pQCT scanner at 165 μm resolution and a second time with a μCT scanner at 56 μm resolution. A third set of images with a resolution of 165 μm was created by downscaling the μCT measurements. The μFE models were created directly from these images. Orthotropic elastic properties and the average tissue von Mises stress of the specimens were calculated from six FE-analyses per specimen. The results of the 165 μm models were compared to those of the 56 μm model, which was taken as the reference model. The results calculated from the pQCT-based models, correlated excellent with those calculated from the reference model for both moduli R2>0.95 and for the average tissue von Mises stress R2>0.83. Results calculated from the downscaled micro-CT models correlated even better with those of the reference models (R2>0.99 for the moduli and R2>0.96 for the average von Mises stress). In the case of the 3D-pQCT based models, however, the slopes of the regression lines were less than one and had to be corrected. The prediction of the Poisson’s ratios was less accurate (R2>0.45 and R2>0.67) for the models based on 3D-pQCT and downscaled μCT images respectively). The fact that the results from the downscaled and original μCT images were nearly identical indicates that the need for a correction in the case of the 3D-pQCT measurements was not due to the voxel size of the images but due to a higher noise level and a lower contrast in these images, in combination with the application of a filtering procedure at 165 micron images. In summary: the results of μFE models based on in-vivo images of the 3D-pQCT can closely resemble those obtained from μFE models based on higher resolution μCT system.

Mr Relaxation Times and Fiber Type Predominance of the Psoas and Multifidus Muscle

1993 ◽  
Vol 34 (1) ◽  
pp. 16-19 ◽  
Author(s):  
R. Parkkola ◽  
A. Alanen ◽  
H. Kalimo ◽  
I. Lillsunde ◽  
M. Komu ◽  
...  
Keyword(s):  
Fiber Type ◽  
Relaxation Times ◽  
Psoas Muscle ◽  
Relative Mass ◽  
T2 Relaxation ◽  
Multifidus Muscle ◽  
Cross Sectional ◽  
Mr Relaxation

MR relaxation times, fiber composition, nonmyofiber space, water content, and fat content of human psoas and multifidus muscle samples of 10 male cadavers were studied in vitro. The T1 and T2 relaxation times of multifidus muscle were significantly longer than those of the psoas muscle. On average, type 1 fibers (slow fibers with a small cross-sectional diameter) predominated in both muscles. There was no correlation between the relative mass of type 1 or 2 fibers (fast fibers with a large cross-sectional diameter) or nonmyofiber space and the relaxation times. The quantity of fat in the muscle did not correlate with the relaxation times either.

On the investigation of homeopathic potencies using low resolution NMR T2 relaxation times: an experimental and critical survey of the work of Roland Conte et al

2001 ◽  
Vol 90 (01) ◽  
pp. 5-13 ◽  
Author(s):  
LR Milgrom ◽  
KR King ◽  
J Lee ◽  
AS Pinkus
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Nitric Acid ◽  
Magnetic Resonance ◽  
Spin Relaxation ◽  
Relaxation Times ◽  
Critical Survey ◽  
Low Resolution ◽  
T2 Relaxation ◽  
Experimental Artifact ◽  
Experimental Protocols

AbstractWe have attempted to reproduce differences in low resolution nuclear magnetic resonance (NMR) T2 spin–spin relaxation times between homeopathically potentised and unpotentised Nitric acid (nit-ac) solutions previously reported by Conte, et al. Using similar instrumentation and experimental protocols, we have shown that it is likely that Conte's original results are attributable to experimental artifact originating in the glassware used for the manufacture of the NMR tubes.

scholarly journals Influence of the calcium hydroxide paste vehicle on penetration into lateral canals

2018 ◽  
Vol 21 (3) ◽  
pp. 282
Author(s):  
Amanda Sousa Vidal ◽  
Daniele Aparecida Leão ◽  
Fernanda Mota Guimarães ◽  
Mariana Oliveira Gonçalves ◽  
Raissa Freitas Pinheiro ◽  
...  
Keyword(s):  
Computed Tomography ◽  
Calcium Hydroxide ◽  
Propylene Glycol ◽  
Group Analysis ◽  
Distilled Water ◽  
Micro Ct ◽  
Micro Computed Tomography ◽  
Respective Group ◽  
Before And After

<p><strong>Objective: </strong>The aim of this study was to use Micro computed tomography (micro-CT) to evaluate the influence of the type of vehicle associated with calcium hydroxide on its ability to penetrate simulated lateral canals. <strong>Materials and methods:</strong> 30 acrylic blocks with simulated lateral canals comprising apical, middle and cervical thirds were used in the <em>in vitro</em> study. The blocks were divided into 3 groups (n = 10) according to the type of vehicle used (chlorhexidine, distilled water and propylene glycol) in the calcium hydroxide slurry, which was inserted in the respective group of simulated canals with a K# 30 file and then agitated with an ultrasonic tip. The blocks were scanned by micro-computed tomography (micro-CT) before and after insertion of the medication. The images obtained were reconstructed and analyzed to obtain the initial volume of lateral canals and the volume of medication that penetrated into them. <strong>Results:</strong> In the intragroup analysis, both distilled water and chlorhexidine 2% were observed to present statistical difference in all thirds of the canal. Propylene glycol showed no intragroup difference. In the inter-group analysis, the propylene glycol paste presented higher values of penetration into the simulated lateral canals than the other groups (p &lt;0.05). <strong>Conclusion:</strong> Propylene glycol used as vehicle of the calcium hydroxide paste provided better penetration results in simulated lateral canals.</p>

scholarly journals PEG-modified gadolinium nanoparticles as contrast agents for in vivo micro-CT

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Charmainne Cruje ◽  
P. Joy Dunmore-Buyze ◽  
Eric Grolman ◽  
David W. Holdsworth ◽  
Elizabeth R. Gillies ◽  
...  
Keyword(s):  
Contrast Agent ◽  
Contrast Agents ◽  
Soft Tissues ◽  
Three Dimensional ◽  
Blood Pool ◽  
Micro Ct ◽  
Micro Computed Tomography ◽  
Poly Ethylene

AbstractVascular research is largely performed in rodents with the goal of developing treatments for human disease. Micro-computed tomography (micro-CT) provides non-destructive three-dimensional imaging that can be used to study the vasculature of rodents. However, to distinguish vasculature from other soft tissues, long-circulating contrast agents are required. In this study, we demonstrated that poly(ethylene glycol) (PEG)-coated gadolinium nanoparticles can be used as a vascular contrast agent in micro-CT. The coated particles could be lyophilized and then redispersed in an aqueous solution to achieve 100 mg/mL of gadolinium. After an intravenous injection of the contrast agent into mice, micro-CT scans showed blood pool contrast enhancements of at least 200 HU for 30 min. Imaging and quantitative analysis of gadolinium in tissues showed the presence of contrast agent in clearance organs including the liver and spleen and very low amounts in other organs. In vitro cell culture experiments, subcutaneous injections, and analysis of mouse body weight suggested that the agents exhibited low toxicity. Histological analysis of tissues 5 days after injection of the contrast agent showed cytotoxicity in the spleen, but no abnormalities were observed in the liver, lungs, kidneys, and bladder.

Evaluation of cigarette smoke-induced emphysema in mice using quantitative micro-computed tomography

2015 ◽  
Vol 308 (10) ◽  
pp. L1039-L1045 ◽  
Author(s):  
Mamoru Sasaki ◽  
Shotaro Chubachi ◽  
Naofumi Kameyama ◽  
Minako Sato ◽  
Mizuha Haraguchi ◽  
...  
Keyword(s):  
Computed Tomography ◽  
Cigarette Smoke ◽  
Structural Changes ◽  
Chronic Obstructive ◽  
Micro Ct ◽  
Micro Computed Tomography ◽  
Obstructive Pulmonary Disease ◽  
Calculated Volume ◽  
Lung Ct ◽  
Time Point

Chronic cigarette smoke (CS) exposure provokes variable changes in the lungs, and emphysema is an important feature of chronic obstructive pulmonary disease. The usefulness of micro-computed tomography (CT) to assess emphysema in different mouse models has been investigated, but few studies evaluated the dynamic structural changes in a CS-induced emphysema mouse model. A novel micro-CT technique with respiratory and cardiac gating has resulted in high-quality images that enable processing for further quantitative and qualitative analyses. Adult female C57BL/6J mice were repeatedly exposed to mainstream CS, and micro-CT scans were performed at 0, 4, 12, and 20 wk. Emphysema was also histologically quantified at each time point. Air-exposed mice and mice treated with intratracheal elastase served as controls and comparisons, respectively. End-expiratory lung volume, corresponding to functional residual volume, was defined as the calculated volume at the phase of end-expiration, and it evaluated air trapping. The end-expiratory lung volumes of CS-exposed mice were significantly larger than those of air controls at 12 and 20 wk, which was in line with alveolar enlargement and destruction by histological quantification. However, CS exposure neither increased low attenuation volume nor decreased the average lung CT value at any time point, unlike the elastase-instilled emphysema model. CS-exposed mice had rather higher average lung CT values at 4 and 12 wk. This is the first study characterizing a CS-induced emphysema model on micro-CT over time in mice. Moreover, these findings extend our understanding of the distinct pathophysiology of CS-induced emphysema in mice.

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