In vivo micro-CT scanning of a rabbit distal femur: Repeatability and reproducibility

Abstract

Before in vivo micro-CT scanning can be used to investigate femoral trabecular microarchitecture over time in rabbits, its repeatability and reproducibility must be demonstrated. To accomplish this, both distal femurs of two six-month-old New Zealand white rabbits were scanned five times each in one day under different conditions (repeatability). Scanning was done at 28 μm isotropic voxel size to produce five image stacks of each femur. Three operators then followed a standard image processing protocol (reproducibility) to isolate two separate cubes from each anterior femoral condyle [total n = (8 cube sites)(5 scans)(3 operators) = 120]. Bone volume fraction (BV/TV) of the eight different cube sites (sample) ranged from 0.408 to 0.501 (mean: 0.453); trabecular thickness (Tb.Th) ranged from 158.1 μm to 185.5 μm (mean: 168.6 μm); and trabecular separation (Tb.Sp) ranged from 179.4 μm to 233.1 μm (mean: 204.7 μm). Using ANOVA and the variance component method, the total process variation was ± 14.1% of the mean BV/TV of 0.453. The sample variation was ± 13.9% (p<0.001), the repeatability was ± 2.1% (p<0.001), and the reproducibility was ± 0.1% (p>0.05). Results were similar for Tb.Th and Tb.Sp. Though the contribution due to repeatability was statistically significant for each of the three indices, the natural sample differences were far greater than differences caused by repeated scanning under different conditions or by different operators processing the images. These findings suggest that in vivo micro-CT scanning of rabbit distal femurs was repeatable and reproducible and can be used with confidence to measure differences in trabecular bone microarchitecture at a single location in a longitudinal study design.

Computer-aided design and finite-element modelling of biomaterial scaffolds for bone tissue engineering

“…When used on small animals, in vivo microCT can be used to evaluate scaffold/tissue integration, tissue formation and scaffold degradation (Komlev et al 2006). In vivo microCT scanning has been shown to be both repeatable and reproducible (Voor et al 2008). This can be obtained with a lower resolution than for in vitro experiments but has the advantage of characterizing the same scaffold at different time points.…”

Standardized Three-Dimensional Volumes of Interest with Adapted Surfaces for More Precise Subchondral Bone Analyses by Micro-Computed Tomography

“…12 However, this approach 11 can be limited since bone measurements either include void 1 volume above the trochlea or omit curved structures above a flat VOI surface. Alternatively, hand-drawn polygonal shapes have been used to delimit irregular structures such as osteophytes, 10 and to separately analyze trabecular and cortical bone in the diaphysis.…”

Biodegradable Magnesium Screws Accelerate Fibrous Tissue Mineralization at the Tendon-Bone Insertion in Anterior Cruciate Ligament Reconstruction Model of Rabbit

“…Scanning with low resolution (large voxel size) relative to the size of the trabecular bone can cause an underestimation of bone mineral density due to partial-volume effects and overestimation of BV/TV, trabecular thickness (Tb.Th) and trabecular separation (Tb.Sp)454647. The trabecular thickness in adult rabbits is approximate 180 μm48, while the smallest voxel size is 41 μm in our used HR-pQCT. Therefore, the voxel size to trabecular thickness in our ex vivo CT scans of rabbits is about 1:4.5.…”