MRI

mri

Thu, 2009-11-05 14:23

I had my annual abdomen MRI today at Northwest Hospital.

Since I had Hepatitis C and was treated for it with interferon and ribavirin, my liver doctor has kept a close eye on my liver: cancers of the liver are more prevalent in people who have had my history. For a while, this meant abdominal ultrasounds every six months, but a while back we switched to alternating ultrasounds and MRIs. I've had three or four MRIs so far.

Before doing the MRI, I get my eyes x-rayed to make sure that I have no metal fragments in them. The MRI's magnetic field can move metal around very strongly, and little bits of metal near your eyes could move and cause a lot damage. Since I do metal work, and use grinders and such, there is always a possibility that I have a bit in my eye that I'm not aware of.

But, the x-rays were clean, and it was on to the MRI.

At Northwest, they take you to a little changing room, where you remove all your clothes (except socks and underwear) and put on scrubs. The room has little lockers for locking up your stuff. You take the key with you, and someone takes you into the MRI room. It's a non-stop noisy machine in a big room with a big window between it and a darkened control room with lots of monitors. There is a narrow bed that you lie on, and the technician starts an IV through which contrast dye is injected during parts of the scan. For my abdomen scan, they strap some kind of plastic frame over my abdomen. All in all, I feel quite constricted. They put a rubber squeeze ball in my left hand: squeezing this will get me out of the tube if I panic, I am told, but I've never used it. They finally put headphones (covered in plastic) on me, and bed slides into the tube.

The tube is very narrow. I always close my eye for the entire procedure, though I've peeked enough to know that the surface of the tube is only a couple inches in front of me. There is light in the tube, but keeping my eyes closed allows me to, I think, eliminate my feeling claustrophobic.

Then the fun starts. The machine is always making some noise, but then the scans are happening, it is very loud, and the sounds made have a surprising variety. Sometimes humming, sometimes thumping, sometimes exactly like an all-hell-has-broken-loose warning alarm. The first time I heard that one, I really wondered whether there wasn't something seriously wrong. Often the sounds are so loud, so over-the-top, that I want to laugh, but usually through the headphones the radiologist tells me "take a deep breath and hold it", so I cannot. It is the most amusing part of the procedure.

For some reason, I felt a noticeable amount of anxiety night before this MRI, and a bit today as well. I decided to try to do a visualization during the MRI to make time go as quickly as possible. So, as soon as I was put into the tube, I imagined I was on a very long, very straight luge run, and that I could look up at the sky and see blue sky and white moving clouds. This worked pretty well, helped by the narrowness of the "sled" and the low amplitude, high frequency irregular vibrations of the machine that are transmitted to my body through the bed: I easily imagined these were the vibrations of the runners on the not-perfectly-smooth ice. There was even cool air blowing through the tube (well, mostly onto my forehead). So that was fun for a while.

It is always toward the end of the procedure that they pump the dye in. They always tell me that they are starting it, though today it was very obvious. I felt a cold stinging in my right arm where the IV was, and soon after I had a strange, hard to describe sensation of being flushed. It was odd. Around that time, the radiologist asked me if I was doing okay, and I mentioned that I felt a bit strange, a bit flushed. She said that this goes away quickly, and it did, but it was the strangest sensation I've ever had during an MRI.

Soon, after 15 or 20 minutes, it was over, and they pulled me out of the tube, undid the IV, and I got dressed and went home. I'll get a letter in a week or two from my doctor probably telling me that everything is fine, but they don't tell you anything immediately after procedure.

miscellany

Fri, 2007-10-19 17:45

This week I've been thinking about weird numbers, a number theoretic concept that, it turns out, hasn't been investigated nearly as heavily (from a computational point of view) as one might think it would have. With another editor at Wikipedia, I've been looking for better lower bounds on odd weird numbers (i.e., a value x that we can be sure that any odd weird number n must be greater than: n>x). I found a paper from 1976 that gives a method for calculating rather large weird numbers, but it says nothing about odd weird numbers. I might try some computations this weekend.

Also this week, I had an MRI on Tuesday. This was my first MRI. My liver doctor wants me to have them once a year to make sure we detect any anomalies (read: tumors) in my liver as early as possible. I've been having liver ultrasounds every siz months since my interferon treatment for hepatitis C, but now he wants to replace every other one with an MRI. I have to say, ultrasounds are more fun. The MRI required an IV, and although I'm not claustrophobic per se, it was a bit unpleasant being in the tube and subjected to quite loud noises (actually, it was kind of funny, too). On the plus side, the MRI is quite short, so it's really not that bad.