Magnetic resonance imaging

My adventures, Kaiser Medical, Hayward, CA - July 11, 2007

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Wikipedia discussion of MRI,
techie stuff,

An sonogram of my kidneys had revealed a 9 mm something - So an MRI was ordered to resolve the situation further.

The MRI folks wanted to assure that there was no stray iron (magnetic material) in my body - especially eyes. They asked if I had ever done machine shop work or welding - in response to a "yes" answer they wanted special x-rays of my eye region to help assure against disaster.

Wednesday July 11th 2007 was the day. I arrived at Kaiser Medical at Hayward, CA as requested 1.5 hours ahead of MRI schedule for the eye x-ray - three views - OK, no metal found :-))

The MRI machine is in a separate little fenced building on the north side of the regular hospital. The fence has big signs about no magnets or magnetic material allowed.

I had previous experience with big magnets in dealing with magnetrons in the military. A magnet is basically a square law device - get twice as close and the magnetic field (and attraction of magnetic material such as a screw driver) is *four* times as strong. Folks are not used to this non-linearity, being more familiar with our gravity which is rather linear on our small scale. The military issued brass fasteners (nuts & bolts), wrenches and work devices to reduce the risk of serious damage/injury as a magnetic material is sucked harder and harder into the magnetic field.

I had brought along a camera and tape recorder, as I had heard that an operating MRI machine is noisy indeed. The staff did not want any magnetic material in the MRI room! - not at all !!.
They did not even want me briefly in the MRI room with my camera. In my haste, I did not even get the model number of the GE MRI machine.


Even the clothes locker key, kept near by me at all times, but *not* in the bore of the machine, was non-magnetic, looked and felt like hard aluminum alloy.

The follow is probably a too detailed recounting of the events:

  1. After filling out a green colored form (with a wooden "lead" pencil) that I did not have magnetic surgical implants, pacemakers, dentures,... I was told to strip to underwear and stockings and put the clothes, camera, recorder, etc in the locker with the aluminum key. I was provided with the classical tie in the back hospital gown, but didn't tie it and they did not offer. There was a sign in the locker room that they wanted only good or excellent reports about their service. As instructed, I locked the locker, and brought the key, with me.
  2. From the locker room, I walked about 15 feet through the administration/control room, into the MRI room.
  3. I placed the aluminum key on a toweled area in the MRI room, and was offered newly unwrapped yellow foam earplugs. I chewed them briefly in my wet mouth to make them even quieter (a trick I learned in the Army where there are REALLY loud noises) and inserted the cool, wet things into my ears - and quickly found that I could no longer understand the questions/instructions given to me. If I wanted to hear I had to remove one.
  4. I laid, feet towards the machine, on the movable bench going into the core of the MRI machine.
  5. I was advised that I would be asked to hold my breath at various times - try to take the same amount of air, the same way each time - as the pictures would come out more clearly that way.
  6. On the bench I was told that I could have my arms over my head (sounds uncomfortable and risky) or along my body, definitely not crossed on my chest! I chose the along the body route, and stick my thumbs under my butt to stabilize the whole bundle.
  7. Then, after laying on the bench and being gently tied down, I was asked if I was claustrophobic or afraid of small places. I answered that I had cleaned boilers, and that would kill or cure any such feelings.
  8. The timing of the question seemed odd - but maybe it is asked so late in the process as to encourage a short answer and compliance?
  9. The bench, with me laying on it, thumbs under butt, started sliding into the core of the MRI machine, the green numbers on the face of the machine increasing rapidly. I decided the numbers might be in millimeters as they increased so rapidly. Soon the numbers were out of sight and I was in the tube of the machine. There were two light strips, one over each nipple, which seemed friendly and a good customer orientation aid.
  10. Soon the machine was making strange clicks which increased to strange old time auto horn sounds. At no time did the machine sound like a drum in a band. But the variety of sounds, often repeated, was interesting.
  11. I am told that to make the protons in the hydrogen in out bodies precess to emit the radio waves the indicate where they are, that "they" set up a basic magnetic field with a big coil, then dither that basic field with smaller coils. Now, with all these various currents and varying fields, other coils are trying to pick up the magnetic fields of the precessing protons, and computers try to localize the positions of the precessing protons - giving a density of hydrogen in each cubic millimeter or less in your body. I have exactly no clue how this is done :-((
  12. I notice a gentle wafting breeze of fresh air in the tube, a nice touch - I am not going to suffocate :-)) just the right temperature, it must be fresh :-)) There is an opening in this cave/tube ;-))
  13. Soon I am told by a voice (from a female god? inside the machine?) to take a deep breath and hold it for 19 seconds. I try to reply that I am ready and am interrupted by some more strange sound from the machine. I guess no reply or acknowledgement is expected. Just do as ordered and be quiet. OK, I've been in the Army ;-))
  14. Soon the voice says to breath normally. I almost acknowledge, but suppress the urge - see, I learn :-)) More noises and clicks
  15. After maybe 30 seconds of clicking and complex sounds and normal breathing, we do the 19 second thing again, the 19 second routine being recycled maybe four times. Then there is a 23 second routine, I wonder if the times will continue to increase, but thankfully this is not a breath holding school.
  16. Then a pause, the voice says that the radiologist is looking at the results. A long pause, I am so relaxed I could nap.
  17. Soon we are at the noises and a few breath holds again - and another long pause.
  18. My thumbs under my butt feel the loss of circulation, a little numb? Hope this does not last too long.
  19. Suddenly there are voices and movement from the end of the tube, and the bench slides smoothly, head first out to where I started, I can see the green numbers changing rapidly. I am untied.

I get off the machine, grab the aluminum clothes locker key, and charge out into the control room, hoping to see the radiologist. No cool bored professional in sight, just a confused looking obvious sub trainee.

I look and the big screen and there is a postcard sized window of what appears to be the anatomy of the muscles of a back. My name is in another window - that is likely the muscles of my back, with no skin, just like in an anatomy book. :-|

Off to get into civilian clothes, and dash back out with camera.

Some new patient it there with signing the green magnetic form with a "lead" pencil just as I had done about 50 minutes before - I head for the screen with camera but am warned off as data for new patient is already there.

  1. I ask about getting the pictures. See the prescribing doctor. What kind of slices did you shoot? transverse, ??? Medical view orientation words failed me, I start hand waving - but the staff member keeps referring to viewing with the doctor - I guess the new customer is there and needing attention :-((
  2. I ask about computing different views. After we understand each other, I am told there is no post processing, what they scan is what you get. (I had been wondering about how to retain great detail while computing different views - the "pixels" optimum for one view would be "averaged" at different angles and there *must* be some loss of detail.)
  3. I felt that I have pumped the well (staff) dry, thanked the staff (now busy with new customer) and left for the parking structure, taking the fresh air route outside the hospital rather than face the maze and claustrophobia inside.

I have since ordered a CD-ROM from Kaiser of the images - we will see what happens. Kaiser seem better at medicine than Records Release.


Ed Thelen

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