The overall weight of opinion below is that titanium should not be a
problem, especially since the person will not be IN the magnet, but only in
the fringe field. Nonetheless, I take no legal responsibility for the
accuracy of the information below!
********************
Dear AMMRL,
A graduate student here has a titanium surgical implant. Does anyone
foresee this as a problem for working near magnetic fields (i.e. placing
samples in 500/600 MHz narrow bore magnets)?
Please send responses to me and I will be glad to forward a summary to
anyone interested.
*******************************
Jeff, Titanium is so nonmagnetic that you can make a probe out of it--in
grad school, I put titanium alloy high pressure vessels in magnets, and noe
(oops, none) of them got stuck in there! So I think it's pretty safe.
*************************
I have a surgical implant (a form of stainless steel) plus braces. I have
not had any problems. My students teased me about the braces sticking to
the magnet, however I haven't kissed a magnet yet.
***************************************
Titanium is not ferro magnetic so there should not be a=20
problem any worse than someone with a stainless steel=20
implant. Of course it's not too late to suggest a career=20
change to banking and finance.
*****************************
My mom had MRI's done after she received a titanium aneurism clip last
year. I would talk to the medic's at your local MRI unit to see what
kinds of implants that would exclude patients from the MRI magnet. =20
The external fields encountered around a 500 or 600 magnet are presumably
significantly weaker than the field inside an imager. (I say that
without actually knowing what they are.)
***********************************************
I can=B4t imagine that a titanium plate would cause problems. We are
measuring NMR-spectra (400 MHz) at elevated pressures and therefore use
sapphire tubes which are closed by titanim valves. We never had problems
caused by the titanium.
************************
We use for high pressure nmr a saphire tube connected to a titanium head,
this=20
goes into the magnet and we have had no problem with the titanium head.
We have used this HP tube on 100, 300 and 600 MHz.
********************************
As many might have told you by now, Titanium is not ferromagnetic=20
and has positive susceptability. In fact, many years ago the sidewalls
of certain high resolution probes were made of Titanium. That's when=20
probes were flat to fit between pole pieces.
*****************************************
Our original high pressure NMR (200 MHz) probe bodies were fabricated
from titanium - not a problem. Assuming the student's implant is does
not contain significant quantities of other elements ...
The usual caveats apply.
***********************************
Saw this post earlier and intended to reply. I have had an artificial
knee from Johnson and Johnson which has a femur implant of a titanium
alloy and a tibial implant of a cobalt alloy, both non-ferromagnetic.
When I checked with J&J, I was told there shouldn't be a problem. I never
got the exact compositions of the alloys but was told NOT to use MRI for
several months post surgery! If such an implant can withstand MRI, the
trifling fields workers about a 300-500mHz magnet are exposed to should
have no effects.
That is the case with me; I have been working quite closely arouind our
magnet, working on temperature control feed lines, and felt nothing.
Now your graduate student may not have such an implant. I suggest you
have him/her contact the manufacturer of the insert and ask whether MRI is
a problem. They will of course have no idea about working around a
spectroscopy magnet.
********************************************
(This is a MRI person replying)
if it is an orthopedic implant, no problem. if it is a cerebral vascular
clip, or cerebral AVM occlusion coil, etc., I would think that you were
putting yourself in an indefensible liability position. After all, there
is no potential medical benefit for this individual that could outweigh the
potential risk of harm to your student.
*************************************
(This is a MRI radiologist replying)
Most likely, it is not going to be a problem. I have a fairly complete
reference book at home regarding device compatibility for MRI. Many such
devices have been explicitly tested and are listed in this reference.
Devices made of titanium generally are OK. If your student can give me the
exact name of the implant, it may be listed in this reference. That is the
only way to know for sure.
*******************(here is a detailed reply*************
To add our experience to your survey, a physician consultant of ours
searched the medical literature for information regarding potential
hazards of titanium implants in the spine (relevant to our particular
case) and concluded there is little cause for concern. There seems to be
ample evidence that MRI (which subjects the implants to a magnetic field
approximately 300 times greater that the stray field of a 600 NB magnet)
of patients with titanium implants of various types is safe, and in fact
titanium is the prefered material for successful MRI imaging. The
medical literature yielded numerous studies which support this
conclusion. The article summarized below is probably the most relevant.
We are nonetheless consulting with the attending physician to get his
opinion on the specific implant which will be used in this case.
-------------
Year Book of Diagnostic Radiology(r) 1994
Copyright (c) 1994 Mosby-Year Book, Inc.
------------
Magnetic Resonance Imaging Evaluation of the Spine With Metal Implants=20
Rupp R; Ebraheim NA; Savolaine ER; Jackson WT (Med College of Ohio,
Toledo)=20
Spine, 18:379-385, 1993 108-94-3-27
---------------------------------
Objective.--The efficacy and safety of postoperative MRI were examined
in 15 patients with spinal disorders who underwent spinal stabilization
with metal implants.
Patients.--Half of the 9 men and 6 women (age, 21-72 years) had
traumatic injuries. Four others had destructive malignant lesions. The
implants used included Alta titanium plates, Roy-Camille stainless steel
plates, H-shaped steel A-0 plates, stainless steel wire, and steel
Harrington rods.
Findings.--Magnetic resonance imaging, performed 2 days to 2.5 years
after surgery, failed to demonstrate movement or displacement of any of
the spinal implants. There was no evidence of significant heating or
other local tissue effects when the soft tissues were examined for
signal change. Steel implants other than the wire produced artifacts
that obscured the device and adjacent tissues. Titanium implants most
often permitted thorough imaging of the spine. Those implants, with 1
exception, produced local signal void but not the surrounding image
deterioration seen with the stainless steel implants.
Conclusion.--Stainless steel and titanium implants in the spine may be
safely imaged without local effects, but titanium implants permit MRI
without the significant image distortion encountered with steel
implants. The importance of MRI in evaluating the postoperative spine
suggests that titanium implants should be used whenever possible.
------------------------------------------------------------------------
Commentary
------------------------------------------------------------------------
This study reinforces the position that spinal MRI and brain MRI are
not precluded in patients with stainless steel or titanium implants. It
is our experience that there is usually local distortion of the magnetic
field, but useful information is still obtained.
***********
Jeff de Ropp
NMR Facility
UC Davis
One Shields Avenue
Davis CA 95616
jsderopp@ucdavis.edu
530-752-7677
530-752-8109 Fax
NMR Facility Web site URL is:
http://www.nmr.ucdavis.edu/
Alternate, equivalent website is:
http://trc.ucdavis.edu/faculty/jsderopp/HOMEPAGE.html