The Temporal Changes of Trabecular Architecture in Ovariectomized Rats Assessed by MicroCT |
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Authors: | A Laib J L Kumer S Majumdar N E Lane |
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Institution: | (1) Magnetic Resonance Science Center, Department of Radiology, US;(2) Division of Rheumatology, Department of Medicine, University of California, San Francisco, California, USA, US |
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Abstract: | To study the short- and long-term effects of estrogen deficiency on trabecular bone, three-dimensional measurements of proximal
tibiae of ovariectomized rats were performed by micro-computed tomography (MicroCT). New three-dimensional (3D) techniques
were employed to characterize the trabecular architecture from 0 to 110 days post-ovariectomy (OVX). These new methods no
longer assume a plate or rod model of bone, but calculate trabecular thickness, separation, and number and their distribution
by placing maximal spheres into the 3D representation of the structure. The model type of bone was quantified with the Structure
Model Index (SMI). Utilizing these methods we found a rapid loss of trabecular bone in the first week after OVX. After the
first week bone mass declined further, although the rate of loss was lower. In addition there was a complete change in model
type from plate-like to rod-like within 7 days post-OVX, and then a very constant SMI after 12 days. After an initial thinning
of trabecular structure, further bone loss seems to occur through removal of trabeculae, while the trabecular plate thickness
remains constant. The heterogeneity of the network could be quantified by intra-individual standard deviation of local separations,
which showed a stair-like progression, with a plateau between 12 and 60 days post-OVX. This study provides new insights into
ovariectomy-related changes in cancellous bone structure evaluated by 3D MicroCT. In addition, these data suggest that the
rapid change of model from plate-like to rod-like post-OVX may potentially introduce biases in the parameters that are determined
using model-based algorithms, and these biases may modify the impact of age-related or therapeutic changes.
Received: 19 December 2000 / Accepted: 16 April 2001 |
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Keywords: | :3D architecture – Micro-computed tomography – Ovariectomy – Trabecular bone |
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