5 ms·
Tldr: he had an MRI twice a week. Cross referenced with other data about mood, diet, blood. Didn't find much out because sample size = 1.
by codeulike 11y ago
Tldr: he had an MRI twice a week. Cross referenced with other data about mood, diet, blood. Didn't find much out because sample size = 1.
- paulddraper 11y agoWell, there was more than one day. But yeah, results limited to himself.
- jackreichert 11y agoIt's just a matter of time before there's a kickstarter for a limited functionality MRI-esk device that will allow the multitudes to scan 24/7.
- kaybe 11y agoWaiting for room-temperature super conduction and enough computation power to even out the effects of an uneven magnetic field (so you do not need to rotate the full device at high speed to average the field).
- russpoldrack 11y agoThere is a lot of ongoing work looking at very-low-field MRI using SQUIDs, but it's doubtful that it will work for functional imaging at any point in the near future.
- agumonkey 11y agoAlso interesting to know that someone can go through 104 MRI per year safely.
- tricky 11y agoThe physics behind MRI is great. All it does is line up the magnetic moments of all the hydrogen atoms in your body, flips their spin with a burst of energy then watches for electrons as they flip back to a lower energy state. Totally safe!
- agumonkey 11y agoAnd spin don't affect biochemistry ? naively I'd say everything have a limit..
- rbinv 11y agoYou might be thinking of CT scans? MRI scans should be harmless.
- agumonkey 11y agoNo, but it was the source of my question. I was curious if MRI had negative side effects that would show when done as often.
- russpoldrack 11y agoThere has been a lot of work looking at bioeffects of MRI in nonhuman animal models. We looked at this work before we started the study, and were convinced that there was no reason to be concerned about bioeffects at the levels of exposure that I was going to undergo. See http://www.mrisafety.com http://www.mrisafety.com for a lot more info about MRI safety
- zitterbewegung 11y agoYou are more likely to get injured from someone misplacing a metallic object and it injuring you. As other people have stated high tesla magnetic fields don't have an inherent detrimental effect .
- dsugarman 11y agoWhy is it so limited in the US? In other countries, they can go well above 10 tesla leading to a dramatic increase in resolution. I assumed it was because there were some inherent danger from more powerful magnets.
- ska 11y agoThat's not really correct. There are high field research magnets, but most of the stuff over 7T are small animal magnets anyway (it is very much easier to maintain homogeneity in the main field over a smaller bore. So you're well into "research only" territory here. There are other trade offs with field strength also, so it really isn't a matter of just "bigger is better".
- dsugarman 11y agoI am talking about research, I almost worked on a project about 5 years ago using >10T MRI datasets from South Korea. The resolution was not on the same playing field as the US datasets available.
- ska 11y agoSuch research scanners exist in the US as well. None of this is clinically relevant, and none of it is US specific. To be fair, the SAR problems become bigger at bigger fields too, which is related to what you are talking about. It's not really sensible to talk about this as a "problem of bigger fields" because it is there for all systems, and furthermore is also pulse-sequence dependent. By which I mean you may have a pulse sequence that is fine at 3T but woudl be dangerous at 7T, or 7T -> 10T or whatever.
- irremediable 11y agoThat isn't actually surprising. There's no reason to think any of the effects are cumulative in any way.
- cvarjas 11y agoMRI magnets primarily interact with the nuclear spin of protons, which can align with or against the field. Adjusting the orientation of the spin should not change any reaction chemistry, so there is no significant hazard. The nuclear spin orientations shift back into their normal equilibrium once the magnetic field is removed. The radio waves generated for the technique can cause heating when the energy is absorbed. This should be limited by how the MRI is designed, however I am not familiar with the detailed design of MRI instruments. More research could be done in this area for very long term effects, but I haven't seen any convincing evidence for concern.
- agumonkey 11y agoHa, thanks for that nice explanation.
- FreeFull 11y agoWon't the strong magnetic field squish the electron orbitals somewhat, causing a minor effect on chemistry? (an even stronger magnetic field would be toxic, in a way)
- refurb 11y agoThere has been a lot of work in the past in terms of doing chemistry in a strong magnetic field. As far as I know, no one has actually seen any difference.
- cvarjas 11y agoThis might be possible but I don't think the effect is significant. Nuclear magnetic resonance spectroscopy is used extensively to analyze molecular structure and monitor reactions. NMR instruments commonly have about 7-14 tesla magnets.
- FreeFull 11y agoYeah, we might not be capable of producing magnetic fields strong enough to noticeably alter the chemistry of anything. I'm not sure at what intensity the effects would begin to be noticeable.
- ozborn 11y agoTrue, but I was pretty surprised to see how large the differences were between his breakfast/caffeine state versus fasting state. That's a substantial difference and pretty interesting. I also think just tracking MRI variation (even for n=1) is useful - this kind of detailed longitudinal tracking simply hasn't been published before.