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@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@autox.team.net
> [mailto:spridgets-bounces@autox.team.net] On Behalf Of Shop at " Just Brits
> "
> Sent: Tuesday, January 04, 2011 4:05 PM
> To: spridgets@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@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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