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Title: hey stroh Post by: birdymaker on November 22, 2007, 08:22:57 AM since we are on the subject, i'm having an mri on my knee next week. the question i have is, how is this possible with all the metal in my leg?
Title: Re: hey stroh Post by: gleek on November 22, 2007, 08:29:49 AM Mmmmm...leg-kebab.
Title: Re: hey stroh Post by: stroh on November 22, 2007, 08:33:26 AM since we are on the subject, i'm having an mri on my knee next week. the question i have is, how is this possible with all the metal in my leg? Good question. It is possible, and we do it all the time. There are many myths, and misconceptions about metal in MRI. The "medical metal" is always fine. Stuff like your's, implants, joint replacements, dental work, etc. Typically that stuff is titanium,(non ferro-magnetic) and while some stuff is stainless steel(ferris) it isn't a problem from a safety stand point. Contrary to shows like House. [sm_cussing] [sm_pain] (I paid for that episode for about a month) The magnet isn't strong enough to pull metal out of a body. The issue is if the metal is close to the area of anatomy we are attempting to image. Your metal is plenty far away from your knee. You pic.s will come out just fine. Even if we are looking at your ankle, we can still get some useful information, though a lot of the area will be obscured by the metal. Nothing we can do about it, can't take it out. Same as dental work. The big things we worry about are loose non medical metal. Car keys, can fly through the air. Office chairs, like dystopia showed, etc. The next is electronics. The magnet will kill them. Cell phones, and of course the biggie....pacemakers. The last two are the most dangerous. In a magnetic field, the field itself has the ability to induce electric current. If that current finds it's way to a "circuit" i.e. pacemaker wires, it cna shock the heart into a bad rhythm. Again, bad. Typically when the current finds a metal object, it is not in a circuit, and thus has resistance. current+resistance = heat. very bad. You however, are good to go. Good luck. 8) Title: Re: hey stroh Post by: birdymaker on November 22, 2007, 08:39:11 AM thank you sir. :)
Title: Re: hey stroh Post by: Spanky on November 22, 2007, 08:43:25 AM Interesting. Basic electrical generation. A conductor, a magnetic field, and reletive motion between the two. So any metal in the body will generate an electric current, for that matter the body itself will. But because the the metal has no resistance there is no heat.
This is a topic I would love to ponder over some other day, my brain doesn't want to work that hard today. Title: Re: hey stroh Post by: stroh on November 22, 2007, 09:01:15 AM Interesting. Basic electrical generation. A conductor, a magnetic field, and reletive motion between the two. So any metal in the body will generate an electric current, for that matter the body itself will. But because the the metal has no resistance there is no heat. This is a topic I would love to ponder over some other day, my brain doesn't want to work that hard today. Relative to "the field". And my brain is the same state as yours right now. :P Title: Re: hey stroh Post by: stroh on November 22, 2007, 09:03:19 AM Coming up on 5SST, Holiday edition. ;)
Title: Re: hey stroh Post by: gleek on November 22, 2007, 09:13:08 AM http://www.healthsystem.virginia.edu/UVAHealth/adult_radiology/mri.cfm
Quote Due to the use of the strong magnet, MRI cannot be performed on patients with implanted pacemakers, intracranial aneurysm clips, cochlear implants, certain prosthetic devices, implanted drug infusion pumps, neurostimulators, bone-growth stimulators, certain intrauterine contraceptive devices, or any other type of iron-based metal implants. MRI is also contraindicated in the presence of internal metallic objects such as bullets* or shrapnel, as well as surgical clips, pins, plates, screws, metal sutures, or wire mesh. *You do live in/near the most dangerous city in America after all. ;) Title: Re: hey stroh Post by: stroh on November 22, 2007, 09:19:39 AM http://www.healthsystem.virginia.edu/UVAHealth/adult_radiology/mri.cfm Quote Due to the use of the strong magnet, MRI cannot be performed on patients with implanted pacemakers, intracranial aneurysm clips, cochlear implants, certain prosthetic devices, implanted drug infusion pumps, neurostimulators, bone-growth stimulators, certain intrauterine contraceptive devices, or any other type of iron-based metal implants. Troo Dat! Very dangerous. Quote MRI is also contraindicated in the presence of internal metallic objects such as bullets* or shrapnel, as well as surgical clips, pins, plates, screws, metal sutures, or wire mesh. [sm_bs] See: Shellock, Frank MD et al MRI saftey *You do live in/near the most dangerous city in America after all. ;) LOL True. In reality, we take precautions when dealing with bullets, or shrapnel type fragments, depending on their anatomical location. We have turned away patients with those objects lying to near critical neurological structures, for fear of heating and injuring those structures. Bullets near the spinal cord, brain, eyes, etc. [/quote] Title: Re: hey stroh Post by: Clive on November 22, 2007, 03:00:16 PM There are many myths, and misconceptions about metal in MRI. The "medical metal" is always fine. Stuff like This correction has been brought to you by the fine folks at Twoiron Speling and Grammer Nahtzees, Lmtd. |