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we're here at the university of texas

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medical branch specialty care center

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which is in league city just south of

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johnson space center and we're joining

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today dr roy viaskos who is one of the

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many doctors looking at the changes that

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astronauts experience in their eyesight

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when they're in space he in particular

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has been looking to using mri to track

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those changes and he's going to tell us

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a little bit about that today thanks so

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much for joining us thank you so much

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for having me here all right well why

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don't we start with why would you use an

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mri to look at eyes

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well so mri is modern technology

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that allows us to look at the anatomy of

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the body

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using

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magnetism

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the eyes are

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structures that have a lot of fluid in

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them and mri is really good to look at

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structures that have fluid

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since the astronauts have had problems

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with their visual fields mri now allows

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us using modern technology to have very

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high resolution imaging of the orbits

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and of the eyes we are actually using

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doing scans that go through the eyes of

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the astronauts that

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are less than 0.6 millimeters in size

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each of the dots that make up for the

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image

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and this will allow us to actually

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follow and check out things that would

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happen macroscopically inside of an eye

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so and in the optic nerve that goes

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behind it for those of us who don't know

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what exactly is an orbit okay so

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basically the face has two big cavities

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uh that are to just hold the eyes in

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right so we call those the orbits so

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you've been doing this for a while now i

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think you started with the the last

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three of the shuttle missions have you

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been able to get some good data from

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them yes so we have been doing using mri

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on the astronauts

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for around

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eight years

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um here um the new experiment that we

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started with the veip started five years

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ago okay and uh

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we did

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the last three shuttle missions here and

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then all the soyuz project so i guess

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you've gathered a lot of data is it

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helpful data well the the main thing

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that we do with the data is we do

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a clinical

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read of the mri just like we would for

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the brain of any subject that came into

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the magnet

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the additional information that we get

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out of the study

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is being analyzed right now and it's

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part of research what exactly are you

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looking for in the data

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so the data that we get from the

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astronauts

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we have we scan the brains

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so we get to see how the brain looks we

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also get to scan the orbits just like we

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discussed and the orbits will find how

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the eye looks and how the optic nerve is

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the optic nerve connects the eye with

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the brain and then there's a sheath

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around the optic nerve that we also look

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at because we have seen changes in

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astronauts before and after they come

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from space

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and not only the optic globe but also in

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the optic nerve and in the optic nerve

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sheath you're looking at the optic nerve

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sheath thin is it getting smaller or

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bigger some of the astronauts

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have shown to have a distended optic

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nerve sheath

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and also the optic nerve becomes a

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little bit more torturous okay at the

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same time there's some flattening of the

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back of the eye

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and that especially true in the ones

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that have had visual changes what

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exactly does the sheath control

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we we really do not know that that is a

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great question we know that that all of

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these are a result of changes possibly

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of pressures of the whole system one of

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the important things to understand is

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that the eyes are actually actually not

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nerves they're really extensions of the

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brain okay so when the optic nerve

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sheath distends it could be also that

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the pressure inside of the membranes

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that

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cover the brain is increasing

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so that could be one of the causes of

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the changes that we are seeing and we're

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actually exploring that all right so

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what exactly is this behind us this is

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the mri right so this is an mri machine

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the mri machine is a what where you're

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seeing here is a huge magnet so right

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now this magnet produces 60 000 times

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the magnetism of the earth

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so we use that to actually align the

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atoms of in the body as the body goes in

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there and once we have aligned all the

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atoms we choose the atom that is the

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most frequent one

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in the whole body which is hydrogen

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right we then

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are we're able to make all the hydrogen

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atoms kind of dance

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to the same magnetic vector because of

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the huge magnetism and we kind of tilt

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those mag those that magnetic vector

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using radio frequencies we transfer

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energy to those atoms and they tilt and

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once we take the radio frequency out

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they want

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to stand up again to the same magnetic

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field and they'll liberate that energy

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okay and then we use basically antennas

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to detect that energy that's liberated

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and tweak it a little bit to get an

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image so you get images of the

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astronauts uh once before flight and

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once after right yes so we

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usually

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do an mri just before they go into the

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mission

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and we try to put them into the magnet

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in the first three days after they come

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back to earth

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and the reason to that is we really want

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to be able to detect changes as soon as

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they happen before

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the gravity of earth changes or reverts

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any of the changes that could have

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happened in space have you been able to

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draw any conclusions from all this so

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far what we have seen is that

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some of the

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changes that we have identified in the

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orbits

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are similar to changes that we see in

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terrestrials that have increased

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intracranial pressure

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and that is one of the things that we

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really want to concentrate our efforts

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right now is to make sure

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or we want to know what is the cause of

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all these changes that we have seen in

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the orbits and our goal is to identify

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countermeasures and

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hopefully this could be yes this could

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be related then to because we

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transferred to counter measures that we

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can take to avoid this from happening

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again okay so so what do you do with the

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mri okay so with the mri

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what we do is

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we

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scan the brain

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we look

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at the big picture of the brain of the

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astronauts that's called the macroscopic

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brain

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at the same time we are going to scan

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the orbits

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use a much higher resolution to look at

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the orbits and we can really see very

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small details and i was explaining to

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you last time those details can be

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up to 0.6 millimeters

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in in small changes that we can detect

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with the mri but the interesting thing

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is that with the mri we don't only see

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macroscopic changes

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we can also detect microscopic changes

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of the hydrogen within the brain

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so one of the things that we do is we do

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we actually diffuse the water molecules

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within the astronauts brain by using

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what we call gradients

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and that type of imaging is called

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diffusion tensor imaging

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and it will give us information

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about the microstructure of the brain

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and the the water within the brain

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things that we cannot see with our naked

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eye but it will actually give us

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function and we can map all the fiber

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tracks within the white matter

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and we can see if there make microscopic

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changes within it

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a third great thing that we do is that

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we're able to also see flows

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and by seeing flows we expect to

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quantify those flows and possibly be

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able to have an indirect way of

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measuring intracranial pressure okay so

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if increased intracranial pressure could

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be one of the causes

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of the findings that we're seeing

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then through mri we expect to be able to

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have a relaxed correlation between the

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imaging findings through flows and

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intracranial pressure changes so you've

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seen a lot of astronaut eyes you want to

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take a look at mine now sure why don't

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you take a seat all right and keith will

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help us out okay

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okay

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i'll put the head coil on now

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okay what is this this here is a uh it's

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a coil this is basically a fancy antenna

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that takes the pictures of the inside of

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all right

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so any instructions

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ah the only instructions at this point

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are just try your best not to move

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okay so what we're looking for when

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we're looking at an a patient in a

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magnet like brandy especially when it is

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an astronaut

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is at the brain

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here you can see the head and in the

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middle you have the brain

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and we can scroll

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and see all the structures inside of the

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brain

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you can see the white matter

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and the cortex

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we can also see the eyes and this is

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especially something very important for

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this project and in the eyes we can look

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at the eye globes you can see here

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the eye globe and this is the lens

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as we scroll down you can see that the

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eye is connected posteriorly with

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the optic nerve and this structure that

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we have right surrounding the optic

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nerve is the optic nerve sheath that we

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okay