Oral Presentation 33rd ASM of the Australian & New Zealand Bone & Mineral Society 2023

Revealing bone remodelling dynamics with longitudinal imaging (#100)

Han Liu 1 , Pholpat Durongbhan 1 , Jemima E. Schadow 1 , Mateus Oliveira Silva 1 , Catherine E. Davey 1 , Kathryn S. Stok 1
  1. Department of Biomedical Engineering, The University of Melbourne, Parville, Victoria, Australia

Introduction

Combining image registration and in vivo micro-computed tomography (microCT) imaging has allowed quantitative assessment of bone remodelling at local sites in mouse models. Previous longitudinal studies have primarily been conducted using a two- to four-week scan interval [1]. However, the turnover rate of murine trabecular bone was reported to be as high as 4.9% per week [2]. To provide additional insights into bone remodelling activities, more frequent observations between those time points are needed. We hypothesise that bone remodelling rates in healthy mice change significantly from one week to the next. In this study, we aim to uncover these remodelling dynamics by combining longitudinal microCT imaging with image registration.

Method

Four healthy C57Bl/10 mice (n = 8 knees) were scanned weekly for 9 weeks using microCT (vivaCT80, Scanco Medical) at 10 µm voxel size. Three-dimensional image registration was performed to overlay follow-up scans with their baseline to define common volume of interest (VOI) for localised bone analysis. Dynamic bone morphometry, such as mineral apposition rate (MAR) and mineral resorption rate (MRR), was calculated based on the formed and resorbed bone extracted from the overlaid follow-up images (Fig.1a). Measurements of standard bone morphometry were also performed to monitor microstructural changes over time.

Results

Preliminary results from a fully processed knee are shown in Fig.1. Variance in bone remodelling rates, from 2.79 µm/day to 9.55 µm/day, are observed for MAR (Fig.1b), and from 2.57 µm/day to 9.38 µm/day for MRR (Fig.1c). Similar magnitudes of MAR and MRR for each time interval, representing similar thickness of formed and resorbed bone, match the constant trabecular thickness over time (Fig.1d).

Discussion and Conclusion

Preliminary results point toward changes in mice bone remodelling dynamics from one week to the other. Increasing temporal resolution can provide additional insights into these processes.64b8c1787f5fd-Fig.+1.jpg

  1. Botter, S. M., et al., Arthritis and Rheumatism, 2011, 63(9), 2690–2699.
  2. Jilka, R. L., et al., The Journals of Gerontology: Series A, 2013, 68(10), 1209–1217.