Ask  Dr. Lauro

Whole Body CT (“CAT”) Scans as a Preventative Tool:  Should You Do It?
by Dr. L. William Lauro

When I was a kid I watched the TV show Star Trek off and on.  I was never a real “treky,” but I did enjoy watching the show.  One thing that particularly fascinated me was the way Dr. McCoy would take this hand held device and scan it over a person and immediately know what was wrong with his body. I thought how cool that would be to be able to scan someone to determine if there was anything wrong with them well in advance of physical symptoms developing.

Later, after I had become a doctor, I realized just how wonderful it would be if we had such a device. Then in the early 1980’s the CT scanner became reality and I thought it was a God-send. We could finally look deep into the body and see things that might be abnormal long before they got out of hand.

Then with the advent of the MRI scanner the resolution became even greater and we could see even more.  We physicians truly live in an exciting time!  Now medical technologists have taken the CT scanner one step farther: they have written software so that the machine can scan the entire body in just a matter of minutes, thus allowing the radiologist to see abnormalities in multiple areas of the body long before they manifest themselves.

The question then is this: If this is so great, so easy, so wonderful, and so accurate, why aren’t we all rushing out to have these whole body CT scans, and not only that, but why aren’t we having them on a regular basis?

Whole Body CT Scanning:  the Cost

One reason we don’t all run out and do this is that it is expensive and our health insurance usually does not cover it. The cost of the whole body CAT scan is generally around a thousand dollars.

Procedural Concerns: 

So let’s say you find the $1000 cost acceptable.  The next problem is a procedural one: Who is responsible for the findings that might be discovered from the CT scan itself?  You do not have to have a referral from a physician to have the whole body CT scan.  So if something abnormal is found, who is responsible for following this up and taking care of it?

You might answer that you would simply take the results to your family doctor and he would handle it from there.  But your doctor didn’t order the test.  He or she may not be familiar with the particular type of scanner used, the facility that did the test, and how accurate the results are.  Your physician may therefore be very reluctant to get involved without first doing his own history, exam, and even other lab tests so that he is comfortable that the patient is not unnecessarily getting pushed into getting diagnostic procedures that are not indicated. So simply walking in off the street and getting a whole body CT scan is not as straightforward as one would imagine.

What do the experts think and suggest?

The American College of Radiology has recently reiterated its recommendation against full body CT scanning, sighting a lack of evidence that it is effective in prolonging life in patients who have no symptoms and no family history suggesting any disease. The radiology group also expressed concern that widespread screening would uncover numerous small abnormalities that might not necessarily affect a person’s health, but would then put someone on the hook for doing further diagnostic tests and procedures and some sort of follow-up. These further diagnostic procedures and tests can have complications and risks in and of themselves (more about that later).

Additionally, the FDA, at this time, does not recommend whole body CAT scanning either.  This is because the whole body scanners that are available without an order from a doctor do not perform “contrast scanning”.  Contrast scanning is much more specific and sensitive for picking up disease. This type of scanning involves the injection of a contrast material into the body, which then accumulates in certain organs and highlights very small lesions or tumors much better than non-contrast scanning. Unfortunately some patients (and this is very rare) will have a serious allergic reaction to the contrast material, and so the whole body scanners that are located in the mall or down the street from you don’t permit contrast scanning because of the risks of adverse reactions, which most places are not prepared to handle. This non-contrast scanning significantly reduces one’s ability to pick up the smallest and earliest lesions.

We just don’t have the medical studies to answer whether non-contrast whole body screening is really that effective in picking up early disease, especially in individuals who do not have any symptoms or any risk factors for specific disease

What if you have a family history of a particular disease, or are in a high-risk group?

Now we are getting somewhere. For example, CT scanning of a smoker's lung might be quite reasonable.  Scanning a person’s heart that has risk factors for coronary artery disease might be very reasonable. Doing a screening CT scan on a person’s intestines who has a family history of colon cancer might be very valuable. You will notice that the CT scans I am suggesting are organ specific. They are directed specifically at one organ system.  But the advantage of doing whole body scans, as we discussed above, may not be as clear cut.

Whole body scans:  What about radiation exposure?

CT scans work on the basis of serial x-ray images that a computer puts together into a picture for the doctor. Thus, when one has a CT scan of a certain organ, one gets a certain radiation dose. Now, when you start scanning the entire body, the radiation exposure goes up significantly. Does that cause any problems? We don’t know yet. Studies need to be done to determine this. Wouldn’t it be a terrible irony if one underwent this type of scan, found no problem at this time, but then years later developed cancer because they were exposed to too much radiation?

What about false positives?

A false positive occurs when the machine sees something that in actuality is not there. The problem is that we don’t know that it is a false reading at this point and won’t know until we go in biopsy the lesion. So if you go to your local CT scan establishment and order a whole body scan for yourself and they tell you that you have a small lesion in your lung or in your kidney or wherever, what do you do next?  Do you go off to a surgeon and have a biopsy?  And if you, do what are the risks of that?  As I said in a prior article regarding general anesthesia, a small number of people every year will die from anesthetic accidents. It just can’t be avoided because some people are allergic to anesthesia and can’t tolerate its effect. So now we are exposing people to invasive tests that they might not really need because the whole body CT scanner had a false positive result. Once again we need more studies in this area. 

What about false negatives?

False negative means the CT scan has missed the abnormality (therefore implying that the patient is fine) when in reality there is a very early tumor brewing inside. By missing the lesion on the whole body scan one has a false sense of security.  So even if you start developing symptoms of an early cancer, you may have the tendency to dismiss these and not and seek treatment because you have been told that everything is fine.

In addition to this, a negative whole body scan might give the patient the impression that he or she doesn’t have to have any kind of further periodic screening exams such as mammograms, breast exams, Pap smears, colonoscopy, etc., which is not true at all.

My view:

I believe there is a place for organ specific screening CT scans in patients who have certain risk factors, but I am not sure I would advocate whole body screening at this point.  I believe that whole body CT screening should only be advocated after proper research has been done which tells us which patients to screen and how often, just like other screening tests.  Therefore, my recommendation for now is to use CT scan screening only in patients who have certain risk factors or certain symptoms, and only after visiting your physician, who is best qualified to help guide you with this decision.  The other benefit of going to the physician first is that he can order contrast CT scans, which are much more accurate.