Naked Science Forum
Life Sciences => Physiology & Medicine => Topic started by: Tyson Vaughan on 19/08/2005 16:35:05
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Here's a question for Chris.
Full-body CT and MRI scans have apparently become de rigeur in the States, where it seems that anyone who can afford it is asking for one as a part of his or her regular physical.
My question is, basically, what do you as a doctor think about this popular trend of asymptomatic people clamoring for full-body scans?
I suppose that if these scans were cheap and plentiful, it would be unwise not to get them, but given their steep cost, is it worth it to invest in such a scan every year or five years or ten? Is this scan craze also occuring in the U.K. or is it just an example of the collective insanity of my native country?
Thanks for your time.
In theory, there is no difference between theory and practice, but in practice, there is.
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Well, I´m not Chris, but maybe I could answer part of your question. Here in the Netherlands, it´s standard not to provide those kinds of tests if the examination outcome doesn´t indicate the need for them. Most of the physicians over here are reluctant to write a request for it, because mostly this kind of conduct would upset the patient more than that it would help the patient. Most of the tests are inconclusive if there isn´t a high suspicion for a certain disease that requires such a test.
The trend of requesting full-body scans is rising, mainly because the media gives us the idea that this is possible. The doctors are confronted with the issue of providing the patient of what she/he asks for and the diagnostic value of the test. Until now, giving advice about the test being necessary or unnecessary helps a lot, most of the patients are content with this information, but the decision is still theirs to make.
[:P]
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Here in the US we have one extra medical incumberance. It is called a Lawyer. He earns his money by suing on your behave, any doctor because the doctor didn't find something that was there. So in the tradition of CYA, Doctors here prescribe everthing they think they can get away with, and the medical profession goes along with it to protect from themselves from the lawyers. Besides they get part of the Bill.
So, in order for this to become common practice in Japan, the Neiderlande and England, you will need to order 20 lawyers for each CT and MRI machine you buy. It is not a problem, we have a good stock of lawyers eager for new opertunities.
David
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Screening CT is very much en-vogue in the US where people sue first, then ask questions later. But CT scanning as a screening tool is a poison chalice because it delivers huge doses of radiation to the body, potentially needlessly.
In fact, whilst a chest X-ray delivers a radiation dose equivalent to about 5 days worth of cosmic radiation (i.e. the amount of radiation you would naturally be exposed to just through living your life), a CT scan bastes you in 5 years worth of radiation.
The result is that you could well be triggering the very thing you seek to prevent by screening - cancer.
Therefore, for the majority of people this is probably not a justifiable approach to screening. But for some patient groups, with a much higher risk of cancer, it is worthwhile because the pick up rate will outweigh the risk.
Chris
"I never forget a face, but in your case I'll make an exception"
- Groucho Marx
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Thanks for the replies, all.
David, you're right, of course, about the litigious nature of the U.S. But as I understand it the upswing in the use of full-body scans is not because doctors are prescribing them more often, but because patients are seeking them out and requesting them on their own.
Chris, what about MRI scans? That's just a magnetic field, right? No harm done?
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We in the US are growing more concerned about living long and prospering (Spock). Some of this full body scan and specialized heart scans may be a part selling people a promise of good health. Here in the states about 70,000 people die of heart diease every year while 80,000 die from medical error. So these scans are seen as a way to find some of the problems that doctors are missing.
If the cost goes down and the quality of data interpertation goes up, this may eventually become a common practice for a health checkup. I guess the measure is how much of our income goes to health. It is the fastest growing industry in the U.S.
David
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I am curious about the MRI also.. I just had one done on Friday! Several weeks ago I had a ct scan on my brain.. And ex-rays etc. So I would be grateful to hear some more currant information on this subject as this subject is now about two years old! Could some of you please update this.. I did read the podcast information on these but would like to know a bit more.
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just a question... if i had back x rays done one week and then a ct scan on my back the next week... um... should i not have any x rays for a long time for anything? because they just did one on my mouth too... and this has all been since january... is that unsafe then?
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Thats why I was asking too! LOL Had several ex rays of my heart then ct scan on brain then MRI Friday not full body but MRI none the less!
At one point during the MRI i thought he reached over and was going to pull me out as I felt what I thought was his hand brush down my arm very slowly when I looked over he was not there but it was a sensation of something moving down my arm like someone very lightly rubbing downward on my arm just after the pounding began for about the 3rd time.. It was weird it had to be the movement happening under my skin from the magnetic whatever .. It was very weird. I understand that it displaces your molecules or something and when it stops they all come back together to form an almost perfect picture of what is happening inside etc. It is very odd. Can that hurt you having all those molecules separate like that?
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MRI will not expose you to radiation. It is a uniform 1.5 Tesla magnetic field (which is very strong). Therefore if you have certain prosthetics or ferromagnetic material in your body or with you, you put yourself at risk by taking this scan. Otherwise the MRI scan itself is considered relatively harmless. People have had hundreds of MRI scans with no problems.
Note that sometimes a contrast agent is injected when conducting MRI scans. One may have an allergic or otherwise negative reaction to this. Also note the difference between MRI and fMRI. These full body scans would be MRI scans.
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Most recommendations ended up coming out against full-body CT screening due to the radiation risk.
Here's a recent reference:
Hall EJ, Brenner DJ. Cancer risks from diagnostic radiology. British Journal of Radiology 2008; 81(965): 362-378.
Full-body MRI, aside from being very expensive, as others have pointed out, runs the risk of picking up a lot of 'incidentalomas' - you see a unusual lymph node here, a hypodensity in the liver there, and you end up working each up simply because they were seen and now your physicians may feel they 'need' to... And working things up have associated risks...e.g. biopsy, etc.
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Thanks for all the information regaurding both ct and MRI .