Objectives
In microgravity, bones and muscles are not used as they are on Earth. As many
studies have shown, this altered use results in calcium loss, degeneration of
the skeleton, lengthening of the spine by expansion of the intervertebral
discs, change in spinal bone marrow composition and muscle atrophy.
Bed-rest patients on Earth show this same musculo-skeletal response with the exception
of bone marrow alterations. Magnetic
Resonance Imaging (MRI) is one method that can be used to measure the resulting
muscular and skeletal changes. MRI is a safe, non-invasive scanning technique
that uses a large magnet and low frequency radio waves to form an image by reading
the amount of hydrogen in an area of the body. These images can be used to examine
soft tissues in the body, as well as determine muscle volume, spinal bone marrow
mass and cross-sectional area of intervertebral discs.
The objectives for this study were to: (1) measure the muscle volumes of the
calf, thigh, back and neck using MRI before and after flight to compare muscle
performance; (2) determine and compare spin-spin
relaxation time and muscle volume changes using MRI to estimate flight related
muscle atrophy; (3) determine the change in intervertebral disc size in the
lumbar
spine after flight and determine the rate of recovery after return to 1-G;
(4) determine the bone marrow content of the third
lumbar vertebra before and after flight using MRI spectroscopy; and (5) document the
frequency, type, severity and location of back pain during and after space flight.
Shuttle-Mir Missions Approach MRI testing consisted of the following:
· Bone marrow spectroscopy (L3) The crew also filled out questionnaires during flight and postflight to document
the frequency, severity and location of back pain or discomfort.
Results Earth Benefits Publications Principal Investigators Inessa Kozlovvskaya, M.D., Ph.D. Co-Investigators
Mir-21/NASA-2, Mir-22/NASA-3, Mir-23/NASA-4, Mir-24/NASA-5, Mir-25/NASA-6, Mir
26/NASA-7
Magnetic Resonance Imaging was performed pre- and postflight using a 1.5 Tesla
Siemens Magnetom MRI system (1.5 Tesla denotes the strength of the magnet used
for the test) with various coils, including spine, Helmholz neck and whole body
coils. These coils are the antenna of the MRI system that broadcast the radio
frequency signal to the patient and/or receive the return signal to form an
image. Specific coils are used to image different parts of the body; for example,
Helmholz coils are used to image the cervical spine and muscles in the neck.
· Muscle volume of the neck, lower back, calf and thigh
· Muscle T2 (spin-spin relaxation time) of the calf
· Lumbar spine disc size, lumbar spine length
Measurable decreases in muscle volume were present during flight, which presumably,
but not necessarily, represents muscle atrophy. These changes appeared to be
maximized within the first 4 months of flight. Compared to bed rest without
exercise, the inflight muscle changes were less except in the back muscles.
Recovery in all muscle groups was complete within 30-60 days after return to
Earth, similar to recovery after bed rest. Muscle volume and T2 changes were
observed during the first days and weeks after return from space flight compatible
with muscle damage. A small, but not long-term, change in disc size was observed
following these flights. Postflight bone marrow changes with some significant
differences was also observed compared to the shorter duration Life and Migrogravity
Spacelab (LMS) Shuttle flight. Although about 47% of the crewmembers reported
some back pain during flight, the duration and magnitude of this problem was
apparently not of major concern for long-duration flight. A more important consideration
may be the potential for significant injury/pain after flight since about 40%
of the crewmembers reported significant postflight discomfort lasting for a
number of days to weeks. This may be an important consideration for visits to
planets with significant gravity after lengthy flights in microgravity.
Countermeasures developed as a result of this study will benefit patients with
bone diseases, such as osteoporosis, and those confined to extended bed rest.
A paper reporting the muscle results is in preparation.
Adrian L. LeBlanc, Ph.D.
Baylor College of Medicine
Institute of Biomedical Problems
Valentine Sinitsyn, M.D.
Victor Oganov, M.D.
Oleg Belichenko, M.D.
Daniel L. Feeback, Ph.D.
Linda Shackelford, M.D.
Harlan Evans, Ph.D.
Thomas Hedrick, M.D., Ph.D.
Chen Lin, Ph.D.
 |
Curator:
Julie Oliveaux
Responsible NASA Official: John Uri |
Page last updated: 07/16/1999
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