It’s a wonderful, Star-Trek kind of fantasy: have a machine scan your body and turn up any abnormalities in minutes, with no pain, no inconvenience and little fuss. Some patients actually do it: with whole-body CT scans, or more targeted CT scans aimed at the colon (often called virtual colonoscopy — President Obama had one) or the heart.
The problem is there’s no good evidence yet that these scans are worth the expense or the huge dose of X-ray radiation that a patient receives: typically the equivalent of 400 chest X-rays with a single CT scan.
General Electric, a manufacturer of CT scan machines, is trying to get the Food and Drug Administration to give its official approval to the use of CT scans as a substitute for traditional colonoscopy. The application is still pending. At a hearing this week, FDA scientists are expected to complain about the pressure they felt from agency superiors to approve the application despite their concerns about the radiation risks. Read more on this in an article by Gardiner Harris in the New York Times.
Whole body screening with CT scans is something that few sober doctors recommend, unless they own one of the machines. The FDA has a good discussion here explaining why an apparent “abnormality” found with a whole-body scan can mean nothing, while the scan can also miss true disease.
The bottom line is that the images produced by these machines are good, but not good enough to start cutting out the abnormalities they seem to show. With colon, heart and other body parts, no surgeon will operate based solely on a CT scan. They want a closer look with a scope that shows the actual organ — as a colonoscope does.
The other important fact to know about whole-body screening is that if you feel good and have no disease symptoms, the odds are very high that nothing is wrong with you. No screening device yet beats the human brain at picking up signals of abnormality (with a few exceptions like the silent disease of high blood pressure).