At 58 years old, Bill Z. worried he was running on borrowed time. His father died of early heart disease. His mother died of cancer. Although Bill felt well, he wondered if his body harbored a killer that could sprout at any time. He had read about CT scans that screen your whole body for disease and he wondered, "Does it really work?"

Like most things in medicine, the answer to Bill's question is yes and no.

What Can a CT Scan Tell You?

A CT scan uses x-rays to produce three-dimensional computer images of the bones, brain, heart, lungs, intestines, and other vital organs inside the body. From these pictures, a doctor can find a tumor or other irregularity. In fact, doctors commonly use CT scans to look for suspected problems in a sick person. However, using CT scans to screen for abnormalities in a healthy person involves a much more complicated balance of potential benefit and harm.

What About Total Body Scanning?

Questions arise among the experts when CTs are used to scan the whole body for disease rather than specific areas. While scanning specific areas of the body to look for certain conditions (such as scanning the heart to look for heart disease) may be appropriate in some people with risk factors, this is different than scanning the entire body without a clear purpose. Many of us will have small abnormalities that can be found with this whole body image that may or may not be signs of a serious condition.

Doctors have even created the term, “incidentalomas” for tumors—often benign—that are found “incidentally” by regional or whole body CT scanning. These incidentalomas may be found in the thyroid, parathyroid, kidneys, adrenals, liver, kidneys, or brain. Finding an incidentaloma can lead to further testing or even surgery, and it is more likely to lead to anxiety and cost than improved health outcome or saving of life.

What most providers worry about is whether doing CTs in normal people will generate a high number of false positives and false negatives. False positives occur when a scan of a healthy person's body finds something that looks suspicious for disease (such as an incidentaloma) but turns out on further exploration to be harmless. This outcome can generate needless worry and cause side effects from other tests now needed to "rule out" a problem.

False negatives occur when something appears normal at the time of the test, but the person actually has a disease that will manifest in the near future. In other words, the test fails to pick up the disease and the person is "falsely reassured." Experts argue that currently there is just not enough experience with total body scanning in normal people to know if the false positive and false negative rate is low enough for this to be a good test. It is therefore believed that this type of CT screening is unlikely to discover serious disease in people without symptoms. The potential harm may be greater than the presumed benefit. The FDA states that currently there is no data demonstrating that whole body CT screening of individuals without symptoms provides a greater probability of benefit than harm.

What Are the Controversies?

Other doctors argue that since we have the technology of the CT scan, why not use it to obtain information about a person's health status so it can be used to help make decisions. The answer is that medicine is driven by evidence and so far there is no evidence available for making any recommendations about total body CT scans in otherwise healthy people.

The risk of exposing yourself to unnecessary radiation concerns many people. However, the US Food and Drug Administration points out that "the radiation from a CT scan may be associated with a very small increase in the possibility of developing cancer later in a person's life." This is something to keep in mind if you are a healthy person who is trying to decide if you should have a whole-body scan. Another consideration is how often you plan to have this test. If you want it repeated on a regular basis, radiation doses, no matter how small, will add up quickly.

Screening tests should undergo several trials to make sure that all benefits outweigh all risks. In total body CT scanning, this has not been done.

What Are Other Issues to Consider?

Currently, many radiology centers offer total body CT scans. The cost varies depending on where it is done. It is not covered by health insurance, so you will bear the cost.

Total body CT scans are not recommended like other screening tests, such as a mammogram or colonoscopy. These tests are consumer-driven, meaning they are directly marketed to consumers, who ask doctors to do them.

Also, since total body scanning is relatively new, no one knows how often it should be done. For someone with risk factors, like a family history of heart disease, repeated screenings over time may be helpful. Again though, the answer is unknown. Take the time to discuss the pros and cons of total body testing with your doctor before you follow through with it on your own.