lproven | On MRI scans

green_amber asked me if I had ever had an MRI scan.

Yes, I have, though not since about 1995. Bloody terrifying experience, especially since they were doing my head to look for whiplash injuries (of which the only significant one was buggered semi-circular canals. I still have a sense of balance, but it's visual - I have to see. In the dark, I feel my way along walls, get sick and dizzy and fall over a lot.)

I vaguely expected some marvellous 21st-Century technology like a giant tricorder or something. A big donut machine that they wheel you through like a barcoded tin of pea soup which then goes "ping!" and tells them what ails you.

Ohhhh no.

It's a motorized electromagnet the size of my kitchen. And I've got metal limbs.

They very carefully edged me into the centre of the far wall, facing the middle of the machine, then carefully wheeled me straight into the middle of the machine.

The stories rather implied that my piercings - since I do not fuck around with earlobes and nipples, preferring to go straight for major bones and 18" steel rods - would be attracted to the magnet. This thing weighing about 3 tons and being so strongly magnetized that now, even when turned off, it has a vast residual field. I envisioned myself flying manikin-like across the room and sticking to the side of the casing like an enormous, irate fridge magnet. However, since the thing can't be turned off, the only real way to remove this particular ornament would be to either:

[a] disassemble the entire machine, or
[b] cut off my left leg and right arm in situ.

Once I was correctly positioned, they turned it on. I lay inside a 3 ton toroidal electromagnet like the custard in a donut while hydraulic rams slowly twirled it around me in increments of a few degrees. As fast as possible. This means it is LOUD.

But you must stay totally still; if you move, the image blurs and they have to do it again - making it last longer.

My head was in the hole of the donut, which was acutely claustrophobia-inducing. A small fan blew air on my face and they talked to me by intercom from behind a large thick screen wall, which was most unreassuring. I could not talk back, of course, nor even breathe during the scan runs.

It took 20min for the preliminary scan and about 35-45 for the main hires one.

The point of computer-aided tomography via nuclear magnetic resonance imaging, as ani fule kno, is to make the nuclei of all your hydrogen atoms vibrate in synchrony. Atomic nuclei are very small. This vibration is, ergo, very rapid.

If a larger object – say, a few kilogrammes of surgical steel – tries to vibrate so rapidly, the net effect is to heat it up. (Heat is, of course, merely a form of vibration. It’s all vibes, man.)

So if the field spread enough to affect my prostheses, they’d get hot. Thus I would slowly be cooked from within, like a slab of meat in a very large microwave.

They kept telling me to warn them if I felt my arm was getting warmer.

This also signally failed to comfort me or help me to relax.

And it was all, essentially for naught; I was okay, the damage that was done was already known. This is the single more reassuring aspect of the experience; at least of 1995 or so, I didn’t have a brain tumour, for example, unlike my mate Alisdair “Jim” Sutherland, whose finally nailed him last year – RIP, old son - or my mates Philip Parkhouse and Gordon Hill, who both got away with it at the price of deafness in one ear. And indeed big bad Barry White.

This is just one reason why I should not, in general, fall off a motorbike again.