MRIs and headlights

Sun, 2010-10-31 14:08

This week I had my annual abdominal MRI. It went well, despite some anxiety that I was feeling leading up to it. You see, the way it works is I lie down on a narrow table. Technicians strap me to it, and start an IV in my arm (sometimes in my hand). They put large headphones on my ears, which muffles a lot of sound, and then the table slides into a tube with me on it. The tube is narrow, so there is only a few inches of space in front of my face. I close my eyes and keep them closed the whole time I am in the tube. Through the headphones, the technicians speak to me. The only thing I ever have to do is hold my breath. Periodically, I hear them say things like, "For the next one, you will hold your breath for 15 seconds. Hold your breath!" and I inhale and hold my breath. Then there is a repeating series of loud sounds, often like an alarm. The sound is the most surprising thing about MRIs: they are quite varied, and quite loud. From wikipedia:

Switching of field gradients causes a change in the Lorentz force experienced by the gradient coils, producing minute expansions and contractions of the coil itself. As the switching is typically in the audible frequency range, the resulting vibration produces loud noises (clicking or beeping). This is most marked with high-field machines[42] and rapid-imaging techniques in which sound intensity can reach 120 dB(A) (equivalent to a jet engine at take-off),[43] and therefore appropriate ear protection is essential for anyone inside the MRI scanner room during the examination.

I don't think the MRIs I get are quite that loud, but still they always make me laugh: it all seems like a test to see if they can make me stop holding my breath via noises.

In between the breath holding bits, there are long pauses when I don't have to do anything. In these bits, I sometimes get a little claustrophobic, but never badly. I can feel that my feet are outside of the tube, and that always helps. Last year, I did a visualization in which I imagined I was on a luge run on a sunny day (there is always a fair amount of light in the tube). It was hard to imagine the turns, but still it gave me something to do. This time, I found I didn't need to do any visualizations: I felt quite comfortable the whole time.

At the end of the time in the tube, they use the IV to inject a dye. I can feel it moving into my arm, and sometimes feel it in my arm, or my hand. Last year, when I held my breath after the dye went in, I got a very strange sensation in my chest. This freaked me out a bit, but it only lasted a few seconds. I mentioned it to the technician (there is a microphone in the tube) and they said that was normal. This time I didn't feel anything like that at all.

Overall, a pleasant and interesting experience.

In other news, I bought myself a headlight for my bike. I already had two full-blown headlights, plus a little backup one, but they are old or bulky or don't work well with the larger diameter of my modern handlebars. So, I got a Light and Motion Stella 300. I wanted a single headlight, with a battery I could mount under my stem, all slick-like. So far, on one 90 minute ride last week, it has proven itself to be awesome!


Fri, 2009-11-13 00:57

I had another echocardiogram (i.e., an ultrasound on my heart (I don't know why it gets a special name)). I've had one once a year for the last several years. They are my favorite medical diagnostic thingee: they are painless, only take about 45 minutes, and give all sorts of useful data, and there are cool colors and sounds. The worst part is either that your torso gets covered in goo (the microphone-like device they rub around on your chest needs to have this special goo on it to make better contact with your body, basically you don't want any air between the mic and your skin), or the slightly painful part where you have to bend your chin up, and the technician tries to shove the mini-mic into the "jugular notch of your sternum" (I think there is a more romantic term for this, but it escapes me) to try and see behind the sternum.

I get these once a year to keep an eye on my heart because I have a bicuspid aortic valve. It's not really causing any problems now, but it could, so we must be vigilant. My cardiologist seems like he'd be happy doing the echos only once every two years, but doing it every year makes me feel better.


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.

a bit o' the old a-fib

Sun, 2008-01-27 17:47

Well, I had a touch o' the old a-fib on Wednesday, so I had to go to Northwest Hospital on Thursday and get cardioverted. Here's the strip showing the actual conversion:

One 150 Joule shock, and I was back in business. Note the irregular beats on the left, the big flat-top shock, and then the regular beats on the right. Presto!

This was my first one of these in just over three years, my longest afib-free stretch since I started having this particular problem. Can't really complain about that.