Currently
some medical imaging facilities are promoting a new use of computed tomography
(CT), also called computerized axial tomography (CAT) scanning. This use
is referred to as whole-body CT scanning or whole-body CT screening, and
it is marketed as a preventive or proactive healthcare measure to healthy
individuals who have no symptoms or suspicion of disease. At this time
the FDA knows of no data demonstrating that whole-body CT screening is effective
in detecting any particular disease early enough for the disease to be managed,
treated, or cured and advantageously spare a person at least some of the
detriment associated with serious illness or premature death. Any such
presumed benefit of whole-body CT screening is currently uncertain, and such
benefit may not be great enough to offset the potential harms such screening
could cause.
Public health agencies and national
medical and professional societies-the American
College of Radiology, the American
College of Cardiology / American Heart Association, the American
Association of Physicists in Medicine, and the Health
Physics Society -do not recommend CT screening.
CT is
a diagnostic imaging procedure that uses x rays to obtain cross-sectional
images of the body. Since its introduction and rapid adoption into medicine
in the mid-1970s, CT has become recognized as a valuable medical tool for
the diagnosis of disease, trauma, or abnormality and for planning, guiding,
and monitoring therapy.
Important information regarding
whole-body CT screening:
- Such
screening provides uncertain benefit with potential for some risk -
The most likely outcomes of CT screening of a healthy person with no
symptoms of illness are:
- Normal findings or
- Suspicious
findings requiring follow-up tests
Normal findings carry the possibility of inaccuracy and false reassurance.
For suspicious findings, follow-up may involve simple, non-invasive
testing. It may also involve invasive procedures associated with
surgical risks of anesthesia, bleeding, infection, scarring,
or it may entail
additional radiological exams, associated with radiation risk and
the potential risk of allergic reaction to injected contrast
material.
In any case, it is unlikely that CT screening will benefit an individual
lacking signs or symptoms of disease by detecting a serious disease
early enough to treat it and alter the outcome significantly.
- Radiation
Dose - CT screening subjects the individual screened to radiation
exposure from x rays. The
dose a patient receives during a typical CT procedure is generally
much larger than the radiation doses associated with most conventional
x-ray imaging procedures. The principal risk associated with the radiation
dose resulting to a person from a CT procedure is the small possibility
of developing a radiation-induced cancer some time later in that person's
life. For a patient with a medical need, the benefit of a diagnostic
or therapeutic CT procedure recommended by a physician normally far
exceeds the small cancer risk associated with a CT procedure. For a
person without symptoms, CT screening is unlikely to discover serious
disease, and the potential harm to the individual may be greater than
the presumed benefit.
- Scientific Studies - There
are no data demonstrating that whole-body CT screening of individuals
without symptoms provides a greater probability of benefit than harm. Nor
is there any scientific study known to be underway to develop such data.
Although there are several
ongoing investigational studies of the effectiveness of using CT to
screen people, the studies are focused on high-risk groups for specific
diseases (e.g., cigarette smokers for lung cancer). In such studies only
a limited portion of the body is irradiated, not the whole body, and only
screening for a specific type of disease is being evaluated, rather than
screening for just anything that might be found anywhere in the body.
- No
Food and Drug Administration (FDA) Approval of CT for Screening -
Statements by CT imaging facilities that imply FDA "approval," "clearance," or "certification" of
CT for screening procedures misrepresent the actual situation. FDA
has never approved or cleared or certified any CT system specifically
for use in screening (i.e., of individuals without symptoms), because
no manufacturer has ever demonstrated to the FDA that their CT scanner
is effective for screening for any disease or condition.