In our lab, we do about 1000 MRI's a year for research. We don't do nuttin less
than a 7 Tesla magnet. And there are no open 7 Tesla systems that I am aware
of. When you are doing functional imaging of activity in the brain, 1.5 Tesla
just does not give the resolution necessary. We are currently working with a
bunch of kids from 8 - 21, we have a set up that allows them to "practice" in a
tube with all the noise. If they get jittery, we get the next kid on the list.
As I understand it, the noise comes from the reversing of the polarity of the
magnet. It is not really any physical movement, just a sudden reversal of the
polarity causes a rapid displacement of the air inside, causing a shock wave,
also known as sound. I may be off in that analysis, but it is pretty close.
Larry
On Jan 4, 2011, at 7:50 PM, corvallis at peoplepc.com wrote:
> From: http://en.wikipedia.org/wiki/MRI
> " Claustrophobia and discomfort:
> Due to the construction of some MRI scanners, they can be potentially
> unpleasant to lie in. Older models of closed bore MRI systems feature a
> fairly long tube or tunnel. The part of the body being imaged must lie at
> the center of the magnet, which is at the absolute center of the tunnel.
> Because scan times on these older scanners may be long (occasionally up to
> 40 minutes for the entire procedure), people with even mild claustrophobia
> are sometimes unable to tolerate an MRI scan without management. Modern
> scanners may have larger bores (up to 70 cm) and scan times are shorter.
> This means that claustrophobia is less of an issue, and many patients now
> find MRI an innocuous and easily tolerated procedure.
>
> Alternative scanner designs, such as open or upright systems, can also be
> helpful where these are available. Though open scanners have increased in
> popularity, they produce inferior scan quality because they operate at lower
> magnetic fields than closed scanners. However, commercial 1.5 tesla open
> systems have recently become available, providing much better image quality
> than previous lower field strength open models."
>
> ...bill in corvallis
>
> ===================================================
> -----Original Message-----
> From: spridgets-bounces at autox.team.net
> [mailto:spridgets-bounces at autox.team.net] On Behalf Of Shop at " Just Brits
> "
> Sent: Tuesday, January 04, 2011 4:05 PM
> To: spridgets at autox.team.net
> Subject: Re: [Spridgets] 7 MRI's
>
> Good grief, Bill <G> !!
>
> << The wave of the future. >>
>
> They are OLD <G> !!
>
> I would have to look-up WAY past the 8 or 9 [9, I really think is
> correct] I've had in the past two [2] years but I think the first
> "open" one I've had was a tad over 10 years ago !!
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--
Larry Macy
78 Midget
Keep your top down and your chin up.
Larry B. Macy, Ph.D.
macy at upenn.edu
Senior IT Program Director
Neuropsychiatry Section
Department of Psychiatry
University of Pennsylvania
3400 Spruce St. - 10 Gates
Philadelphia, PA 19104
Ask a question and you're a fool for three minutes; do not ask a question and
you're a fool for the rest of your life.
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