Non-invasive Investigation of Bone Adaptation in Humans to Cumulative Daily Mechanical Loading

Principal Investigator: R.T. Whalen, PhD (NASA)

Project Staff: Gary S. Beaupré, PhD; C.H. Yan, PhD; T. Cleek, MS; David P. Fyhrie, PhD; and J. Vogel, MD

Project Category: Osteoporosis

One objective of this study is to characterize the in vivo performance of a suite of new Quantitative Computed Tomography (QCT) techniques for measuring bone density. A key element to monitoring the risk, progression and treatment of osteoporosis is the use of bone densitometry, defined as the quantitative assessment of bone mass, density or structure using any of a variety of imaging modalities. Bone densitometry has become an indispensable clinical tool for measuring bone mass and relating bone mass to fracture risk.

Quantitative Computed Tomography is currently the only established non-invasive imaging modality that can measure the true volumetric density and distribution of bone. It is also the only established technique that can measure cancellous bone density separately from cortical bone density. We have developed new software for processing QCT images that produces highly accurate and precise results using bone substitutes and phantoms containing known materials.

The underlying hypothesis of this project is that the accuracy and precision of our new QCT techniques will enable us to determine volumetric bone density in smaller volumes of interest (VOI) within a bone and to detect changes in bone density sooner than is possible with current QCT techniques. By monitoring regional changes in small VOI's we can examine for the first time site-specificity of bone remodeling and reversibility of bone loss.

In this study we will: 1) validate the accuracy of measuring volumetric bone density with our new quantitative computed tomography (QCT) algorithms; 2) determine the relationship between bone density from QCT and histological parameters such as bone surface area density; 3) validate the accuracy of a 2D imaging method of obtaining long bone structural geometry; 3) investigate the relationship in young and elderly men between daily loading and bone density in the calcaneus; and 4) compare our results to computer simulations of bone adaptation.

Publications:

Yan CH, Whalen, RT, Napel, SA: Method for beam hardening correction in quantitative computed X-ray tomography. US Patent #6,018,562, issue date: November 27, 2001.

Les CM, Whalen RT, Yan CH, Cleek TM, Beaupré GS, Willis JS: The x-ray attenuation characteristics of human calcaneal marrow do not change significantly during adulthood. J Orthop Res, 20(3): 633-641, 2002.

Cleek TM, Beaupré GS, Matsubara M, Whalen RT: Accurate measurement of bone density with QCT. 15th International Bone Densitometry Workshop, July 21-26, 2002, Monterey, CA.

Funding Source: NASA

Funding Status: Funded