Feasibility Study: QCT Modality for Risk Surveillance of Bone - Effects of In-flight Countermeasures on Sub-regions of the Hip Bone (Hip QCT) - 08.29.18

Overview | Description | Applications | Operations | Results | Publications | Imagery

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Science Objectives for Everyone
With data collection now complete, Hip QCT demonstrates the utility of quantitative computed tomography (QCT) to describe unique changes in hip bone structure due to spaceflight which cannot be currently captured by routine clinical testing, and further describes the ability of in-flight bone countermeasures to mitigate these specific changes. The regions of bone measured by QCT are determinants of fracture risk in the elderly. Hence, the mitigation or restoration of QCT-determined deficits are expected to enhance the management of astronauts’ short- and long-term skeletal health.
Science Results for Everyone
Information Pending

The following content was provided by Jean D. Sibonga, Ph.D., and is maintained in a database by the ISS Program Science Office.
Experiment Details

OpNom: N/A

Principal Investigator(s)
Jean D. Sibonga, Ph.D., Johnson Space Center, Houston, TX, United States

Joyce H. Keyak, Ph. D., University of California at Irvine, Irvine, CA, United States
Elisabeth R. Spector, Wyle Laboratories, Houston, TX, United States
Scott A. Smith, Wyle Laboratories, Houston, TX, United States
Harlan J. Evans, Ph.D., Wyle Laboratories, Houston, TX, United States
Thomas F. Lang, Ph.D., University of California, San Francisco, CA, United States

NASA Johnson Space Center, Human Research Program, Houston, TX, United States

Sponsoring Space Agency
National Aeronautics and Space Administration (NASA)

Sponsoring Organization
Human Exploration and Operations Mission Directorate (HEOMD)

Research Benefits
Earth Benefits, Space Exploration

ISS Expedition Duration
March 2013 - March 2014; March 2015 - March 2016

Expeditions Assigned

Previous Missions
This study shares QCT data obtained from on-going ISS investigations: Bisphosphonates as a Countermeasure to Space Flight Induced Bone Loss, and/or Sprint integrated Resistance and Aerobic Training Study.

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Experiment Description

Research Overview

  • It needs to be understood if long-duration ISS crew members are more susceptible to developing osteoporosis at a younger age because of bone changes that occur during missions in space. Recent research, using an imaging device for the hip called QCT, has described changes in the structure of the hip during spaceflight. This study, for which data collection is now complete, describes how those changes in bone structure and in specific bone compartments affect the strength of the hip bone and how losses in hip strength might be prevented or recovered.
  • This study is also expected to demonstrate that the effects on the hip, described by QCT, are not detected by clinical tests used to diagnose osteoporosis.
  • The study uses the QCT instrument at a local hospital to measure hip structure and to describe how different types of bone loss countermeasures being tested in space (e.g., a drug vs. exercise) distinctly change bone mass in sub-regions of the hip.
  • In addition, a special software analysis tool can compute the fracture load of the hip from the QCT measurements for specifically oriented loads applied to the hip. These results tell if, and how, tested countermeasures affect this index of hip bone “strength” in space. This application enables NASA to integrate biomechanics as it evaluates the risk for fracture in individual astronauts.


Quantitative Computed Tomography (QCT) is a 3-D bone imaging technology that is used typically to scan the hip and spine. QCT is capable of measuring the volumetric bone mineral density (BMD, g/cm3) of separate cortical and trabecular sub-regions, as well as of total (integral) bone. In contrast to the 2-D imaging by dual-energy x-ray absorptiometry (DXA), which uses areal BMD (g/cm2) as a surrogate for fractures due to primary osteoporosis, volumetric QCT at the hip is limited to research applications at this time because there is not enough medical evidence to determine how QCT data should be used in clinical practice. QCT, however, provides additional information on bone structure and increases the understanding of how bones respond to effectors of bone loss or gain.
In 2010, clinical bone experts were convened by NASA to review available medical and research information from astronauts who flew on long-duration space missions. This group of policy-makers in the osteoporosis field recommended that the trabecular compartment of the hip should be monitored for recovery after return to Earth. This opinion was based upon the flight data displaying a discordant pattern of recovery between DXA measurements and QCT measurements. Consequently, this study (for which data collection is now complete) uses preflight and postflight QCT scanning of the hips in ISS astronauts, as a supplement to DXA testing, to evaluate the ability of in-flight countermeasures to mitigate declines in conventional QCT parameters (vBMD of cortical bone, trabecular bone) and to assess complete recovery of spaceflight-induced deficits in the trabecular sub-regions of the hip (i.e., total hip, femoral neck and trochanter).
A secondary aim of this study is to try to distinguish the effects of different categories of in-flight countermeasures/activities on distinct compartments of the hip bone. For example, it might be expected that biochemically-based countermeasures (e.g., the pharmaceutical bisphosphonate agent) would result in a detectable prevention of BMD loss in hip trabecular compartment, while the benefits of biomechanically-based countermeasures (resistive exercise on the (Advanced Resistive Exercise Device [ARED]) would be more apparent in the cortical bone of the hip. Because this was a pilot demonstration with only ten astronauts, Hip QCT will require data sharing with the other flight studies (the Bisphosphonates and Sprint studies) to demonstrate better the distinct compartmental effects of biochemical vs. biomechanical countermeasures.
These different effects on hip morphology should, theoretically, translate to an integrated effect on hip bone strength of the ISS crew member. The combination of countermeasures that impact both compartments would be expected to enhance the protection against bone loss which may result in greater hip bone strength -- as estimated by analyzing QCT data by Finite Element Modeling (FEM) - compared to the sole application of a biomechanical countermeasure, i.e., resistive exercise. To address these assertions, this pilot study includes the following specific aims with QCT hip scans: 1) Characterize the response of trabecular and cortical vBMDs of the hip with QCT scans after spaceflight, 2) Generate Finite Element models from the QCT data, 3) Analyze the Finite Element models to estimate hip bone fracture loads (aka, “hip bone strength”) for specific orientations of loading, and 4) Describe the recovery of QCT-measured changes in hip bone sub-regions (Aim 1) following a 12-month postflight period on earth. Specific focus is on the recovery of hip trabecular vBMD by two years after return. A lack of recovery by two years postflight was identified by osteoporosis experts as a possible indicator for a clinical intervention. This opinion was based upon deficits in conventional QCT measurements (e.g., hip trabecular vBMD) being validated as predictors of hip fracture in the elderly (Black et al, JBMR 2008; Bousson et al JBMR 2011). Based upon this evidence, the overarching goal is to mitigate or restore all skeletal deficits due to spaceflight to prevent combination with expected deficits due to aging. The combined effects may induced premature bone fragility.
The objective surveillance data would help to address the following questions: are in-flight countermeasures and postflight activities sufficient to protect against a decline in hip trabecular BMD? Do countermeasures sufficiently protect hip bone strength to mitigate a risk of overloading the hip with falls during physical activities? Can hip bone strength be sufficiently protected or restored with the current, or self-directed, post-mission rehabilitation regardless of changes in hip trabecular BMD?

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Space Applications
The information collected from this surveillance study is expected to help a clinical advisory panel assess whether there is a need to monitor and prevent spaceflight-induced early onset osteoporosis in long-duration astronauts and to recommend specific preventative countermeasures to spaceflight bone loss, including the optimal timing (pre-, in- or post-flight) for those countermeasures. The QCT data of hip bone structure, and the estimation of hip bone strength by Finite Element Modeling (FEM), provide additional characterization on how hip adapts to spaceflight, which will improve the ability to forecast hip fractures, during a mission, by modeling efforts.

Earth Applications
This study of younger-aged crew members adds to a growing population data set of hip bone strengths, estimated by Finite Element Modeling (FEM). This biomechanical approach to assessing fracture risk is being investigated as an index to assess the efficacy of osteoporosis therapies. This biomechanical approach (estimated fracture load as a new fracture surrogate) may be a more cost-effective and time-efficient alternative to evaluating fracture likelihood in lieu of fracture outcomes – which may take years to occur. This approach may be valuable for the rare, complex subject with bone loss due a condition aside from aging (e.g., menopause or advanced aging).

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Operational Requirements and Protocols

A total of ten subjects performed the preflight and postflight baseline data collection for Hip QCT. Additionally, data were collected before and after the year-long mission of the US crew member launching on 42S.
This investigation required baseline data collection (BDC) only preflight and postflight. No in-flight testing occurred.

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Decadal Survey Recommendations

Animal and Human Biology AH2

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Results/More Information

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Results Publications

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Ground Based Results Publications

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ISS Patents

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Related Publications

    Lang TF, LeBlanc AD, Evans HJ, Lu Y, Genant HK, Yu A.  Cortical and Trabecular Bone Mineral Loss from the Spine and Hip in Long-duration Spaceflight. Journal of Bone and Mineral Research. 2004; 19(6): 1006-1012. DOI: 10.1359/JBMR.040307.

    Keyak JH, Koyama AK, LeBlanc AD, Lu Y, Lang TF.  Reduction in proximal femoral strength due to long-duration spaceflight. Bone. 2009 March; 44(3): 449-453. DOI: 10.1016/j.bone.2008.11.014. PMID: 19100348.

    Lang TF, LeBlanc AD, Evans HJ, Lu Y.  Adaptation of the Proximal Femur to Skeletal Reloading After Long-Duration Spaceflight. Journal of Bone and Mineral Research. 2006 May 29; 21(8): 1224-1230. DOI: 10.1359/JBMR.060509.

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Related Websites

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image Representative image of a clinical Quantitative Computed Tomography [QCT] instrument (left side) with its capability of detecting the transmission of x-rays in hip bone over three dimensions. Representative QCT scan of hip (right side) with mineral-dense cortical bone in red and the trabecular "spongy" bone compartment in blue. Image courtesy of HRP
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image Representative analysis of hip QCT images by Finite Element Modeling. This mathematical model of the 3-D hip structure can be used to calculate the force required to fracture the hip, based upon the 3-D geometry and mechanical properties computed from each astronaut’s QCT bone density. These plots illustrate the von Mises stress distributions in two proximal femora of males representing typical control subjects (left) and fracture subjects (right). Image courtesy of HRP.
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