Marshall Brain's Blog

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A day with an MRI machine

David spent the day inside the bore of an MRI scanner today. The scanner is a huge machine -- a cube about 8 x 8 x 8 feet with a tunnel through the center big enough to hold an average-size adult.

An MRI scanner produces an immense magnetic field, so the nurses and technicians are extremely sensitive about having any metal near the magnet. There are three separate doors you have to badge through to get into the scanner room, and the last one is vault-like, with an immense yard-long handle.

This sensitivity about metal also applies to any metal you might have inside or outside your body. Therefore, they have you fill out a form and declare any internal metal. Here's the list of things they want to know about:

1. Aneurysm clip(s)
   
2. Cardiac pacemaker
   
3. Implanted cardioverter defibrillator (ICD)
   
4. Electronic implant or device
   
5. Magnetically-activated implant or device
   
6. Neurostimulation system
   
7. Spinal cord stimulator
   
8. Internal electrodes or wires
   
9. Bone growth/bone fusion stimulator
   
10. Cochlear, eye or other ear implant
    
11. Insulin or other infusion pump
    
12. Implanted drug infusion device
    
13. Any type of prostheses (eye, penile, etc.)
    
14. Heart valve prosthesis
    
15. Eyelid spring or wire Artificial or prosthetic limb
    
16. Metallic stent, filter or coil
    
17. Shunt (spinal or intraventricular)
    
18. Vascular access port and/or catheter
    
19. Radiation seeds or implants
    
20. Swan-Ganz or thermodilution catheter
    
21. Medication patch (Nicotine, Nitroglycerine)
    
22. Any metallic fragment or foreign body
    
23. Wire mesh implant
    
24. Tissue expander (e.g., breast)
    
25. Surgical staples, clips or metallic sutures
    
26. Joint replacement (hip, knee, etc.)
    
27. Bone/joint pin, screw, nail, wire, plate, etc.
    
28. IUD, diaphragm or pessary
    
29. Dentures or partial plates
    
30. Tattoo or permanent makeup
    
31. Body piercing jewelry
    
32. Hearing aid
    
33. Other implant ______________

I never really thought about how many implantable and replacement devices surgeons are now installing. It's even funnier to think about what this list will look like in 20 years. Everything from eye chips...



to brain implants...



To artificial organs...



To bionic limbs...



As all these implanted technologies become widespread, it is possible that MRI machines become useless because just about everyone has multiple implants.

The other funny thing about this MRI machine is the fact that it had a big GE logo on it. That's funny to me because my mother gave me a GE wireless indoor/outdoor thermometer for Christmas. There's a little temperature sensor outside that broadcasts the outdoor temperature to the displays inside.



It's got the same GE logo on it.

Yesterday, the outdoor sensor started malfunctioning for some reason. Right now it is telling me it is 65 degrees outside, despite the fact that there is frost forming as we speak. The thought that runs through your head is, "Damn, if they can't even get a little indoor/outdoor thermometer to last more than a month, I'm not sure I want my kid inside this machine." It's hard to believe that the same company makes the two products, and probably is a good argument for GE to brand the made-in-China consumer stuff with a different logo.