MRI (thing)

Many people get claustrophobia because they are in a narrow, vibrating, noisy tube, sandwiched under a 1 ton magnet and a table. I was a bit nervous looking at the mammoth machine. It doesn't hurt, but until I realized that the thing was properly bolted and wouldn't fall under the magnetism, I was fine. Plus, they gave me nice music to listen to, in what looks like a stethoscope with thick ear buds to block out the Hmmmmmm. The reason is so that there is no metal, the speakers are outside the machine, piping sound in through tubes. I got to pick the radio station.

During the 1990's, advances in technology created the Open MRI. No, not open source, open enclosure. More advanced RF antennas meant you could move the magnets further apart, and you could pick up weaker signals. Aside from clearer films, you now had a good six feet between magnets. From photos of the new enclosure, you sit on a table. There's half of a hula hoop ring going above you and joining to the sides of the table, to be the antenna. Above you is a large metal circular plate, the magnet. Beneath you is another magnet. It's much roomier, and less noisy. I'm not a radiologist, so I don't know if there's a difference in quality of the films though. Also, now they now use a rare element called Niobium in their superconducting magnets, which comes from South America.

I've had some fun with MRIs too. After I got a head scan with a closed MRI, the tech picked up a screwdriver and gave it to me. Tightly clenching it, I walked in to the machine, and felt an invisible hand begin to tug and tug on the screwdriver. Waving it in the tunnel, it almost latched onto the ceiling. Luckily the machine was turned off, and the outside had some shielding, or I would have been dragged accross the room.

There are two types of closed MRIs, permanent magnets and electromagnets. The reason closed MRIs vibrate so much and are so noisy, is the magnetism. With permanent magnets, one magnet is moved into position relative to the other magnet. There is such attraction generated that the magnet begins to shake. It's perfectly safe, and bolted and wielded into place, but creates a vibration. Electromagnets turn on and off, when it's on, you feel the vibrations. It feels rather like a massage bed set to low. Other causes for the noises and vibration is the moving internal machinery, the antennas moving into place once the magnet is switched off.

The MRI technology was developed at the State University of New York at Stony Brook, where it went by the name NMR, Nuclear Magnetic Resonance. The first machine was built with permanent magnets, dozens of them in metal brick form stacked to form the plates. The lab was situated right above the parking garage, which was unlucky for the cars below. People began to notice that all the cars parked in a certain corner wouldn't start if they were left there for a while. It turns out the machine wasn't shielded enough, and the magnetism was somehow draining all the car batteries below. The floor, as well as the walls, soon got lead or copper shielding after that.

Another interesting story there: One day, the custodian, not The Custodian somehow ignored the red "In Progress" signs and entered while using the floor buffing machine. Immediately the machine was yanked off the ground, and dragged into the tunnel, where I imagine a patient was lying. The patient was OK, just had to crawl out the other side. The custodian was fired, and the radiologists were left with the task of getting a heavy twisted hunk of metal out from in between two permanent magnets. In the end, a tow truck had to use a winch to slowly pull the tangled floor buffer out.

Aside from the clearer resolution and the Open MRI, there haven't been any new advances, except the fMRI which can help determine which parts of the brain are functioning at one time.