In an old copy of a Bruker Site planning guide for 600 magnet written in
1988, one line reads....
"Lowest known field-effect on pace makers 17 gauss"
So with pacemakers of that vintage, the 5 gauss line rule, gave us all a
bit of extra safety & hence fewer lawsuits.
At 05:30 PM 5/3/2004, you wrote:
>Dear Gerd,
>
>One of the more detailed guides to implants and their safety properties is
>the following book:
>
>Pocket Guide to MR Procedures and Metallic Objects: Update 2001
>by Frank G. Shellock
>
>Generally speaking pacemakers are not allowed in MR-scanners although they
>in principle may not be harmed by a limited field strength. Most of the
>documented cases of deaths during MR-procedures (5) that I am aware of,
>are indeed related to patients with pacemakers. I suspect it was the heart
>condition of the patient that caused these deaths. Also, to say that the
>pacemaker function fine in saline outside the body may not be the same as
>to say that it will work in a patient with a heart condition. Finally the
>rather arbitrary 5 Gauss limit that we generally observe, is in my
>experience more detrimental to computers than to people. For all computers
>to be entirely happy I would set the limit to 1 Gauss. But that is another
>story.
>
>Spin up,
>
>73, Peter
>
>At 16.13 +0200 04-05-03, Dr. Gerd Gemmecker wrote:
>>Hi colleagues,
>>
>>a few weeks ago I had a discussion with our university
>>safety commissioner. Normally this is always a very delicate
>>business: one careless word can mean years of trouble.
>>
>>However, this time he surprised me with a new information
>>(at least for me! - although it is already from 2000) he
>>had found in the internet:
>>a clinical study performed on an "in vitro model" (pacemakers
>>in a vessel with salt water, plus "in vivo": 55 patients with
>>pacemakers (44 different models) in a 0.5 T MR tomograph.
>>Result: no adverse effects nor even the slightest deviation
>>in the pacemaker parameters could be detected! Admitted,
>>the pacemakers were set on "asynchronous mode" (i.e., a
>>fixed stimulation rate) to let them run more stable.
>>
>>but at least here is a number (0.5 T = 5000 Gauss)
>>with some reference (that can be quoted!)that it is safe.
>>And there is even a website discussing the results in German
>>(www.herzschrittmacherpatient.de).
>>
>>Our commissioner was very pleased with this and will put
>>it in his next report, when talking about the "safety limit"
>>of 5 Gauss that we are obeying.
>>
>>ah yes, the source is:
>>"MR imaging and cardiac pacemakers: in-vitro evaluation and in-vivo
>>studies in 51 patients at 0.5 T."
>>Sommer T, Vahlhaus C, Lauck G, von Smekal A, Reinke M, Hofer U, Block W,
>>Traber F, Schneider C, Gieseke J, Jung W, Schild H.
>>Radiology. 2000 Jun;215(3):869-79.
>>
>>hope you might find this useful,
>>
>>gg
>>
>>--
>>
>>==========================================
>>
>>PD Dr. Gerd Gemmecker
>>Department Chemie, Organische Chemie II
>>TU Muenchen
>>Lichtenbergstr. 4
>>D-85747 Garching
>>Germany
>>
>>Tel. +49 (89) 289-13308
>>Fax +49 (89) 289-13210
>>e-mail: Gerd.Gemmecker_at_ch.tum.de
>>Internet: http://www.org.chemie.tu-muenchen.de/people/gg
>
>
>--
> _at_ _at_
> ..
>==================================================ooOO==========OOoo======
>| Peter Lundberg Ph: (+46 13) 22 27 90 |
>| MR-Unit Fax: (+46 13) 22 27 92 (alt 22 47 49) |
>| Dept of Radiation Physics Email: Peter.Lundberg_at_imv.liu.se |
>| University of Linkoping |
>| S-581 85 Linkoping Efax: PeterLundberg_at_f013222792.fax.sunet.se |
>| Sweden www: http://www.imv.liu.se/radiofysik/ |
>==========================================================================
>() "To a poet nothing is useless." (SJ) ooOO OOoo
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NMR Facility ph: 319-335-1332
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http://nmr.chem.uiowa.edu/ NMR Facility
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Received on Tue May 04 2004 - 09:19:44 MST