It’s probably not widely known that astronauts are among those who are at high risk of developing osteoporosis. However, it’s true that bone loss is very common in astronauts, especially in astronauts on longer space missions. So much so, that NASA is conducting a study to understand the long-term effects of spaceflight on bone mineral density (BMD) using QCT.
While QCT is regularly used for routine BMD screening, QCT is also used for specialist purposes such as clinical trials because of its capabilities to provide more in-depth understanding of how disease affects bone density by producing 3D volumetric data. In a research setting, QCT is not only used to measure bone density but is also used to asses bone thickness and strength. During spaceflight astronauts can rapidly lose bone mass, similar to the effects of aging on bone mass because of exposure to reduced gravity. It is critical for NASA to understand whether long duration ISS Crewmembers are predisposed to developing osteoporosis at a younger age because of the rapid changes in BMD that occur during space missions.
A panel of clinical bone experts recommended that the trabecular compartment of the hip should be assessed for recovery after returning to Earth. Researchers are using 3D QCT to investigate the changes in bone mineral density (BMD) and examine the extent of bone loss in the hip and spine. QCT scans of the hip were taken pre-flight and post flight to evaluate the effects of long-duration space flight. In contrast to 2D analysis by DXA, QCT is able to distinguish between the metabolically active trabecular and cortical bone. By measuring only the trabecular bone, QCT offers more information on bone status allowing for the earliest detection of changes in BMD and early diagnosis of osteoporosis.
Although it is not used in the NASA study, new Asynchronous Calibration technology, means that QCT offers an additional benefit by eliminating the need to use a calibration phantom underneath the patient during a CT scan and makes it possible for researchers to use images that were taken for reasons other than BMD screening and also retrospectively make use of stored CT scans.
Currently, there’s not enough data to show the extent to which bone loss is recovered when the astronauts return to earth, but by using advanced imaging technologies like QCT we will gain more understanding of how spaceflight affects bone health and countermeasures can be taken to reduce effects.
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