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Musculoskeletal complications (i.e., osteoporosis) induced by microgravity during extended space missions and age-related disorders represent a key health problem. Osteoporosis will diminish both the structure and strength of bone, each considered critical in defining the ability of the bone to resist fracture.
Early diagnosis of such progressive bone loss would allow prompt treatment, and thus, inherently reduce the risk of fracture. Bone mineral density (BMD) measurement is a well-accepted, standard assessment used for the diagnosis of osteopenia and osteoporosis, using dual-energy x-ray absorptiometry in the clinic. However, it is limited to a BMD index and insensitive to the bone's physical properties. Advents in quantitative ultrasound (QUS) techniques can characterize both BMD and the material properties.
Using a newly developed noninvasive scanning confocal acoustic diagnostic (SCAD) technology, strong correlations between SCAD-determined data and bone's structural and strength parameters were observed. Ultrasound has also shown the therapeutic potential to accelerate fracture healing.
The objectives of this study are to develop a combined diagnostic and treatment ultrasound technology for early prediction of bone disorders and guided acceleration of fracture healing, using SCAD imaging and low-intensity pulse ultrasound. The technology will target the critical skeletal sites that may be significantly affected by disuse osteopenia and are potentially at risk of fracture (i.e., hip, long bone and wrist regions).
We will evaluate bone quality in clinical human subjects and at the NASA Johnson Space Center/University of Texas Medical Branch bed-rest facility. Animal models and cadavers will be used for testing the technologys feasibility of identifying bone loss and fracture and for determining its use longitudinally for treatment and monitoring.
A noninvasive diagnostic and treatment technology using ultrasound will have significant potential to prevent and treat bone fracture and will address critical questions in the Human Research Programs Integrated Research Plan related to bone loss monitoring, prevention and recovery.
This year, the research team continued to developing a new generation of the prototype scanning confocal acoustic navigation (SCAN) system to access the bone quality at multiple skeletal sites and to use ultrasound to detect bone fracture. A combined mechanical and electrical array scan modality has been initiated, which can complete the SCAN time at the particular skeletal site in less than 2.5 minutes. The new development is capable of generating noninvasive, high-resolution quantitative ultrasound attenuation and velocity maps of bone for determining the relationship between ultrasonic-specific parameters and BMD and bones physical properties (i.e., stiffness). Several studies were conducted:
- Multi-Site Quantitative Ultrasound Scanner for Osteoporosis Diagnostics - Evaluated at the Distal Radius. The objective of this study was to provide validation of the new mechanical setup for the two-dimensional SCAD system, and evaluate its performance at the distal radius.
- Noninvasive Assessment of Long Bone Fracture and its Potential Healing Process Using Quantitative Ultrasound. In this study, we evaluated a hypothesis that the ultrasonic velocity drop is dependent on the fracture gap size. A three transducers ultrasound system was set up to measure fracture gap size. This was verified by both experiment and mathematical simulation.
- Mediation of Bone Loss with Ultrasound-induced Dynamic Mechanical Signals in an Ovariectomized Rat Model of Osteopenia. This study tested the hypothesis that an ultrasound-generated dynamic mechanical signal can inhibit bone loss in an estrogen-deficient model of osteopenia.
Musculoskeletal decay due to a microgravity environment has greatly impacted the United States civil space missions and ground operations. Such musculoskeletal complications are also major health problems on Earth (i.e., osteoporosis and the delayed healing of fractures). About 13 to 18 percent of women aged 50 years and older and 3 to 6 percent of men aged 50 years and older have osteoporosis in the U.S. alone. One-third of women over 65 will have vertebral fractures, and 90 percent of women aged 75 and older have radiographic evidence of osteoporosis. Thus, approximately a total of 24 million people suffer from osteoporosis in the U.S., with an estimated annual direct cost of over 18 billion dollars to national health programs. Hence, an early diagnosis that can predict fracture risk and result in prompt treatment is extremely important.
Ultrasound has also demonstrated its therapeutic potential to accelerate fracture healing. The objectives of this study are focused on developing a combined diagnostic and treatment ultrasound technology for early prediction of bone disorders and guided acceleration of fracture healing, using scanning confocal acoustic diagnostic imaging and low-intensity pulse ultrasound.
Development of a low-mass, compact, noninvasive diagnostic and treatment modality will have great impact as an early diagnostic to prevent bone loss and accelerate fracture healing. This research will address critical questions related to noninvasive assessment of the acceleration of age-related osteoporosis and the monitoring of fractures and impaired fracture healing.