Wednesday, June 17, 2009

Will Physics Ever Leave Me Alone?

I did magnetic resonance imaging as part of my advanced lab course twenty years ago. I remember having a terrible time with the math, but everything else about the experiment I had forgotten. So I’ve had to check on Wikipedia to remind myself of the basics.

Protons are little electric charges, and they are spinning. This spinning is like electric current moving in a loop of wire. We probably all played with electromagnets in elementary school and saw that an electric current in a wire produces a magnetic field around the wire. So, like a loop of wire, a proton is a tiny electromagnet.

In an MRI machine, a magnetic field is applied to a person’s body. As we know from playing with magnets, when one magnet comes near another, it can cause the other magnet to move and align itself a certain way. So, the protons in the body align themselves with the constant magnetic field. Think of them as lining up like soldiers in perfect formation.

Then, additional magnetic fields are applied to the body. This changes the orientation of the protons (or makes some of the soldiers move out of place a little bit). When these additional magnetic fields are switched off, the protons realign themselves according to the constant magnetic field (like soldiers scrambling to get back into proper place again). As they realign themselves, they release electromagnetic radiation that can be measured by the machine. Protons of different tissues take different amounts of time to realign, so by measuring how long the realignment takes in different places, a picture of varying types of tissue can be formed.

I had only a vague idea of how this would work when the doctor sent me for an MRI as a last ditch effort to find the cause of my symptoms. A distant softly shifting curtain had hung in the background of my head all my life. Sometimes it would be closer, but never was bothersome. But recently I’ve become surrounded by a field of insects. At worst, it’s high summer activity; at best, it’s warm mid-September when there’s just one or two left in the grass, the last holdouts for mating before winter.

My Dad had an MRI recently. He talked about it like it was a landmark for old age. The machine broke on his first time in, and he joked that his brainscans had broken it. When good scans were made at a later date, they told him he had the brain of a young person. Who knew someone that irascible could have such a young brain? Seriously, we think it’s all the balance exercising he gets from bike riding and skiing, but who knows. We in our family are lucky in that we preserve pretty well.

The MRI people called to tell me my insurance would not cover it because of my high deductible. I would have to pay the whole $1023. I canceled the appointment and called the doctor back to see if this was really worth it. His nurse said it was his recommendation, but it was up to me. I paced and thought about it. Really, it had been my choice to have a high deductible. It has saved, in the long run, on premiums over the years. I didn’t want to afford this, but I could. I called the MRI people and set up the appointment again.

I had found one first-hand description of an MRI online that said that the machine was loud, so I took earplugs. At the desk, the receptionist asked how much I would like to pay now. I hate spending money -- I’ve joked that I’m no good at making it, but I’m a fiend at saving it. But when I’ve made a decision and it seems there’s no turning back, I feel rather carefree. “The whole snert,” I said. Really, it was less than half of a new wireless system.

Backstage, one nurse stood by while I put my things in a locker. “All I’ve got now is the metal zipper,” I said. The writer of the online description had said that she had disrobed completely, but this nurse said my metal zipper would be fine. I imagined it catching fire, as if in a microwave oven, spontaneous combustion from the crotch.

I moved on wearing still my T-shirt and shorts and Birkenstocks.

There was to be an IV. Uh oh, I had not been prepared for this. Jangle my nuclei all you want, but I’m not cool with needles that stick and then stay there.

The nurse giving the IV said I had good veins and asked if I drink a lot of water.

I thanked her for the compliment and said I needed to keep hearing those right now.

I averted my gaze as the needle went in. But this time, unlike the yearly blood test I get to check TSH levels, the needle stayed. She put in some saline solution, and the point of entry felt eerily cool on the inside, black ink ejected into already murky water by a fleeing octopus. I waited anxiously for the feeling to go away, and it did after a few seconds, but still, something foreign was inside me now.

She said she would leave the IV connector in my arm, and they would use it to add contrast later.

My non IV-ed right hand got my right earplug in fine, but it could hardly get the left one in. I feared my left ear would be unprotected. There I would be, stuck in the machine, making worse the symptoms that got me here. The nurse said I could use my left hand, and the IV did not hurt when bent my arm. I squeezed and rolled the earplug and tried to stick it in correctly before it swelled again, but I kept hitting the wrong angle. I have this problem before going to clubs too. I felt like I was holding things up. Finally the nurse got me a fresh earplug and put it in herself, and it felt pretty good.

I set the locker key on the windowsill and kicked off my Birkenstocks and sat on the table. The nurse who had given me the IV and helped with the earplug now said that I smelled good. “What is that?” she asked.

”Regular Speed Stick,” I said.

“I thought it was cologne,” she said.

“I like those compliments. Keep ‘em coming,” I said.

I lay back and my head fit into a soft wedge in the table. They added some pads on the sides to help keep my head still. Then, from somewhere, a little cage was swung into position over my head, and with a loss of perspective like happened in La Femme Nikita when Nikita jumped down the garbage shoot to escape the rocket and up became sideways, and I saw the nurse’s glasses and smile where there should have been just the tube interior. It was a mirror now positioned over my eyes, so that I could see out of the machine once I was slid in.

A little squeeze bulb went into one hand. I would squeeze this when I couldn’t stand it anymore, as when Christopher Hitchens dropped the metal rods, or Mancow his cow.

They put a pillow under my legs and a blanket over them and slid me in. People talk about the claustrophobia, but the mirror, which gave me sight of the opening and the room beyond, helped greatly. I could see the nurses in the control room.

Then the noises started. I was grateful for the earplugs. There were brief spurts of fierce vibrations of the sort that, if made by your lawn mower, would convince you that something horrible was wrong. There were a few softer squirting sounds. A nurse, speaking through an intercom, announced the length of each test, which was typically 5 to 10 minutes. When the test proper started, the sound would be a constant


with no variation, for the duration. I imagined my protons snapping to attention and going at-ease, alternately. I wondered when they would start turning into adamantium.

The earplugs kept the noise at bay. I was a little tired because I had not slept well the night before, so lying still was not a problem. And I was no drain on the medical system, for I had paid the old-fashioned way -- with a debit card. Why not enjoy it? I let my mind wander. The symptoms that had lead me there swam around me. Urges to move developed like cumulus clouds in my bones but I let them pass through me. I seemed to lose connection with my limbs. I imagined Svetx beside me as if in a double-MRI-sleeping bag, and it was easy to lie there.

I noticed that the edge of the mirror closer to my forehead was farther from me than the edge closer to my chin. This meant that it was not a mirror, but a prism. I studied its image of the windowsill across the room where I had put my locker key. The position of the box of sanitary wipes on the sill was not reversed, so indeed, this was not a mirror. A mirror would have sufficed, right? So why a prism, which is probably more expensive?

About 2/3 through, they slid me out and put the contrast into my vein. Now, I imagined, I would stand out more clearly in poor light. Take my picture, before it wears off! Or would I appear only in black and white?

I was really very comfortable the whole time. Life outside the MRI machine . . . that was hard. When I was done, I would have to go back to my own freedom of underemployment, which is a molasses of indecision in which I must constantly wade.

The nurses were pleased. I had not moved at all for the whole half hour. They helped me upright and, thinking of my Grandpa who used to say of nurses “Always leave them laughing,” I asked, “Do I have mutant powers now?”

Afterwards, I treated myself to the full buffet at Golden Corrall. If the MRI doesn’t give me mutant powers, surely Golden Corral will.

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