Optimizing a micro‐computed tomography‐based surrogate measurement of bone‐implant contact

Abstract

Histology and backscatter scanning electron microscopy (bSEM) are the current gold standard methods for quantifying bone-implant contact (BIC), but are inherently destructive. Microcomputed tomography (μCT) is a non-destructive alternative, but attempts to validate μCT-based assessment of BIC in animal models have produced conflicting results. We previously showed in a rat model using a 1.5 mm diameter titanium implant that the extent of the metal-induced artefact precluded accurate measurement of bone sufficiently close to the interface to assess BIC. Recently introduced commercial laboratory μCT scanners have smaller voxels and improved imaging capabilities, possibly overcoming this limitation. The goals of the present study were to establish an approach for optimizing μCT imaging parameters and to validate μCT-based assessment of BIC. In an empirical parametric study using a 1.5 mm diameter titanium implant, we determined 90 kVp, 88 µA, 1.5 μm isotropic voxel size, 1600 projections/180°, and 750 ms integration time to be optimal. Using specimens from an in vivo rat experiment, we found significant correlations between bSEM and μCT for BIC with the manufacturer's automated analysis routine (r = 0.716, p = 0.003) or a line-intercept method (r = 0.797, p = 0.010). Thus, this newer generation scanner's improved imaging capability reduced the extent of the metal-induced artefact zone enough to permit assessment of BIC. © 2017 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 36:979-986, 2018.

Neutron microtomography to investigate the bone-implant interface—comparison with histological analysis

“…images) so as to directly compare the values of the individual pixels as well as the indexes of a region. In life sciences, image registration has been employed to help the understanding of tissues morphology and behavior, such as blood vessel structure (McLaughlin et al, 2005) and bone growth (Stalder et al, 2014), based on the comparison, for example, of X-ray tomography scans and histology (Meagher et al, 2017;Stalder et al, 2014), or MRI scans and X-ray radiography (McLaughlin et al, 2005). Two main methods have generally been employed for image registration in the literature (Markelj et al, 2012): feature-based registrationwhich aims at reducing the distance between specific features (points, curves or surfaces) of segmented imagesand intensity-based registrationwhich focuses on matching pixels by minimising a potential based on their grey value.…”

An In Vivo Study in Rat Femurs of Bioactive Silicate Coatings on Titanium Dental Implants

“…Animal studies on rats' femurs are considered valid models for assessing implant osseointegration [29], usually measuring the parameter "bone-to-implant contact" (BIC) on histological images/sections [30]. The bone-implant interface can also be investigated with micro-computed tomography (micro-CT), which enables the 3D evaluation of the bone surrounding the implants and does not preclude further assessments afterwards [31][32][33][34][35]. This method overcomes the limits of histological analysis, such as the fact that a single histological section may not be representative of the bone apposition over the whole implant [36], and the fact that it is hard to obtain serial sectioning of bony specimens containing little metal implants positioned in small animals such as mice [37][38][39] and rats [40,41].…”

A multiscale analytical approach to evaluate osseointegration

“…The technique has been validated to assess bone volume accurately by correlating with histological measurements [ 37 , 38 ] even at fast/low resolution scans (e.g., 14 µm). While some investigators have reported a correlation between micro-CT and BSE-SEM based measurements of bone-implant contact [ 39 ], it is advisable that measurements be correlated with histology and histomorphometry.…”