Method Article

A Sectioning, Coring, and Image Processing Guide for High-Throughput Cortical Bone Sample Procurement and Analysis for Synchrotron Micro-CT

DOI:

10.3791/61081

⸱

June 12th, 2020

 ,  , 
1Department of Biology, The University of Akron, 2Department of Geosciences, The University of Akron

In This Article

Summary

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We employed a geological (coring) sampling protocol to procure cortical bone specimens of uniform size for SRµCT experiments from the anterior aspect of human femora. This method is minimally destructive, efficient, results in cylindrical specimens that minimize imaging artifacts from irregular sample shapes and improves microarchitectural visualization and analysis.

Abstract

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Bone is a dynamic and mechanically active tissue that changes in structure over the human lifespan. The products of the bone remodeling process have been studied substantially using traditional two-dimensional techniques. Recent advancements in X-ray imaging technology via desktop micro-computed tomography (µCT) and synchrotron radiation micro-computed tomography (SRµCT) have allowed for the acquisition of high-resolution three-dimensional (3D) scans of a larger field of view (FOV) than other 3D imaging techniques (e.g., SEM) providing a more complete picture of microscopic structures within human cortical bone. The specimen should be accurately centered within the FOV, however, to limit the appearance of streak artifacts known to impact data analysis. Previous studies have reported procurement of irregularly shaped rectilinear bone blocks that result in imaging artifacts due to uneven edges or image truncation. We have applied a geological sampling protocol (coring) to procure consistently sized cortical bone core specimens for SRµCT experiments from the anterior aspect of human femora. This coring method is efficient and minimally destructive to tissue. It creates uniform cylindrical samples that decrease imaging artifacts by nature of being isometric during rotation and providing a uniform path length for X-ray beams throughout scanning. Image processing of X-ray tomographic data of cored and irregularly shaped samples confirms the potential of the technique to improve visualization and analysis of cortical bone microarchitecture. A goal of this protocol is to deliver a reliable and repeatable method for the extraction of cortical bone cores that is adaptable for various types of high-resolution bone imaging experiments. An overarching goal of the work is to create a standardized cortical bone procurement for SRµCT that is affordable, consistent, and straightforward. This procedure may further be adapted by researchers in related fields who commonly evaluate hard composite materials such as in biological anthropology, geosciences, or material sciences.

Introduction

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With recent advancements in imaging technology, it is now feasible to acquire X-ray imaging data with very high resolution. Desktop micro-CT (µCT) systems are the current standard for imaging cancellous bone due to their non-destructive nature1. When imaging microstructural features of cortical bone, however, µCT use has been more limited. Due to resolution constraints, desktop systems cannot attain the resolution required to image microstructural features smaller than cortical pores, such as osteocyte lacunae. For this application, SRµCT is ideal owing to the greater resolution of these systems1. For exam....

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Protocol

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All specimens were sourced from embalmed cadaveric donors at the University of Toledo, College of Medicine and Life Sciences and Northeast Ohio Medical University (NEOMED), with the informed consent of the donor themselves or the donor's next-of-kin. The University of Akron Institutional Review Board for the Protection of Human Subjects (IRB) deemed these specimens exempt from full IRB review as they were not procured from living individuals. Demographic information including age, sex, and cause of death were available for all donors. The selected individuals did not have documented bone-affecting conditions nor exposure to treatment regimens that may have affecte....

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Results

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The described method of core sampling proved to be highly effective and efficient. Coring specimens using this protocol allowed for the procurement of >300 consistently sized samples for experiments on the CLS BMIT-BM beamline2, with an FOV of ~2 mm at 1.49 µm voxel size. To validate the consistency of core diameter, three measurements were taken along the length (top, middle, bottom) of a subset of human anterior femoral cores (n=69). The average diameter of the cores was 1.96 ± 0.11 .......

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Discussion

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There has been no comprehensive, standardized protocol for procuring uniform and cylindrical cortical bone core samples for high-resolution SRµCT imaging with limited FOV setups. The protocol detailed here fills that void by providing a comprehensive tutorial regarding how to procure consistently sized cortical bone core samples for SRµCT imaging and the subsequent accurate visualization and extraction of microarchitectural data. We have shown that our protocol provides a more standardized and reliable met.......

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Disclosures

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The authors have nothing to disclose.

Acknowledgements

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Research described in this paper was performed at the BMIT facility at the Canadian Light Source, which is supported by the Canada Foundation for Innovation, Natural Sciences and Engineering Research Council of Canada, the University of Saskatchewan, the Government of Saskatchewan, Western Economic Diversification Canada, the National Research Council Canada, and the Canadian Institutes of Health Research. The authors would like to thank the beamline scientists at the Canadian Light Source, particularly Adam Webb, Denise Miller, Sergey Gasilov, and Ning Zu for the assistance in set-up and troubleshooting of the SkyScan SRµCT and white beam microscope systems. We ....

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Materials

List of materials used in this article
NameCompanyCatalog NumberComments
1-1/8" plunge cutting carbide for compositesWarrior6181228.6mm plunge
70% EthanolFisher ScientificBP82015003.8 Liters
Blunt-tipped forcepsFisher Scientific10-300
Centrifuge tubesThermoFisher55398
Crystalbond 509-3 EpoxyTed Pella821-3
CTAnalyserBruker microCTv.1.15.4.0Download and install at https://www.bruker.com/products/microtomography/micro-ct-software/3dsuite.html
Dental Tool KitAmazon787269885110
Diamond wafering saw blade for composite materialBuehler#11-4247
Drill PressJet Mill/Drill350017Model: JMD-15, benchtop drill presses are suitable substites, but typically lack a translatable machine table for positioning samples beneath the drill stem
Fine-tipped forcepsFisher Scientific22-327379
Fixturing clamps for XY machine table for mill/drillMSC Industrial Supply#04804571
Glass microscope slidesTed Pella2600575x50mm slides, 1mm thick
Glass slide chuckBuehler#112488Large enough to hold 75x50mm glass slides
Hot plate capable of reaching 140 °CThermoScientificHP88850105
IncubatorNAPCOModel 4200
Isocut FluidBuehler111193032Lubricant; 30mL
Jeweler's diamond coring drill bitOtto Frei#119.0502mm inner diameter hollow stem coring bit
NReconBruker microCTv.1.6.10.2Download and install at https://www.bruker.com/products/microtomography.html
Oscillating sawHarbor Freight62866
Oven-safe glass dishesPyrex1117715Glass food storage container
Precision slow-speed saw (Isomet 1000)Buehler111280160
Razor bladesAmazon25181
Shallow aluminum tinsAmazonB01MRWLD0R~8cm diameter
Specimen cupsAmazon616784425436 885334344729
Tergazyme detergentAlconox1304-11.8kg box
Ultrasonic cleanerMTI CorporationKJ201508006

References

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  1. Andronowski, J. M., Crowder, C., Soto Martinez, M. Recent advancements in the analysis of bone microstructure: New dimensions in forensic anthropology. Forensic Sciences Research. 3 (4), 278-293 (2018).
  2. Wysokinski, T. W., et al.

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Tags

Cortical Bone ProcurementBone Core SamplingSectioning and CoringHigh Throughput AnalysisBone Specimen PreparationMicro CT Artifact ReductionCylindrical Bone SamplesBone Microarchitecture Analysis

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