Forget Size. It's All About Position

...according to a study I just read.

Well, you could have knocked me down with a feather! I always thought bigger produced better results. That was certainly my perception in my own life. I laughed at people who said things like "size isn't important. It's how you use it" because I thought they were trying to make excuses for their own inadequacies.  I mean of COURSE size is important! Bigger, faster, stronger. Give me Steve Austin over Pee-wee Herman any day of the week. Actually, you can give Pee-wee Herman Steve Austin over me any day of the week too! Not that Steve Austin would have anything to say about it. He's fictitious.

I was quite surprised to read this paper -and it was something that I had learned previously, but I guess I hadn't processed it properly- that size is not the most important thing. What matters most is position.

...when performing an MRI of a weight-bearing joint. 

"What?" I hear you say?

Why? What did you think I was talking about? Get your mind out of the gutter (...Rob)!

The spine is a weight-bearing structure. it consists of a bunch of bones separated by sproingy discs of squishy stuff. Yep. Them's technical terms. The sproingy discs stop the bones rubbing against each other, allow for movement, and act as shock-absorbers.  They can change shape and look different depending on the forces exerted on them; gravitational, as well as lateral and multi-directional forces exerted by the muscles and other bits attached thereon.

So if you photograph these sproingy discs when a person is laying flat, you see them at their sproingiest; happy and at rest, -under no pressure at all- singing little songs to themselves. Sit that person up (the position which puts most load on the spine, apparently), and things can change considerably: The weight of the head (12lbs), shoulders and everything else exerts downwards and the little discs may change their happy tune. They will squish and may even change position relative to other structures in the spine, such as ...say ...the spinal cord. This is probably especially true of the connectively challenged: I.e. people with EDS, Marfans, and other connective tissue disorders.  But of course, this hasn't been studied. <sigh>

It is also true that other weight-bearing joints -especially damaged ones- can look quite different under load than at rest. If your ankle bothers you when you put weight on it, why bother to MRI it with while laying down?  If you think about it, it's perfect common sense. ...Once someone explains it to you. It took a brain surgeon to figure it out in my case, so don't feel bad if you didn't think of it yourself.

Position is important, too. They MRIed my neck with my head straight, then with my head tilted to either side, my chin down, and finally with my head tilted back. The discs didn't move around too much until I tilted me hread back, and I tell you that picture was scary! I often used to sleep with my neck in hyperextension (don't ask me why) and since seeing that picture, I have been training myself not to do it.

Now, I had lovely pictures of myself to post at this point, where I could show side-by-side images of my spine, taken minutes apart, one laying flat and the other sitting. You can clearly see where one of the herniated discs in my neck bulges out a lot more under the  pressure of gravity. But I can't find the feckin CD! Sorry. I will throw in pictures when it shows up -probably in the oven or my underwear drawer.

OK, you've sold me on position, but what has this all to do with size? I hear you ask? Well it has to do this: They have been making MRI machines more and more powerful recently. they have been throwing Gausses and Teslas and probably some other central European geniuses around like nobody's business trying to make the Steve Austin of MRI machines. They had Functional MRIs and diffusion ones and ones which combine MRI with SPECT... and all sort of interesting things which I don't understand, but I'm sure are terribly impressive.  All of these will take fancy pictures of one while laying flat and under no gravitational pressure. This is fine for cancer, MS and probably a gazillion other things for which one might be magnetically imaged.

It is not fine for anything structural, and certainly not for anything weightbearing or subject to gravitational pressure.

And for structural abnormalities, one doesn't need all that firepower. You only need 650,000 Germans (Gauss)  or slightly less than two-thirds of a Serbo-Croat (Tesla). So you don't have to worry about the iron oxide in your haircolour being sucked out by the gigantic magnet. I don't think that is possible BTW (I don't think there is iron oxide in haircolour), I just like the idea of it for some perverse reason. The only people in the world who make positional MRIs is a company called FONAR, and their machines are less powerful.

But that's OK. Because it's position that's important.

Comments

[Keesha Turner]

Excellent post, OSM. Hopefully this technology will help bring advances in our diagnoses and treatment options.