Whole body scanning (WBS) can be defined as a noncontrast CT examination that scans from the mandible to the groin and does not involve any bowel preparation. This test is being advertised to people as a way to detect preclinical evidence of coronary artery disease; colon polyps and cancer; lung cancer; chronic obstructive pulmonary disease; osteoporosis; spinal abnormalities, including disk diseases; abdominal and thoracic aneurysms; and cancer, stones, cysts, and/or other lesions of the thyroid gland, the parathyroid glands, the abdominal organs, and the reproductive organs.
Despite claims made by some scanning facilities, the FDA has not approved this procedure. In fact, the FDA has not approved any CT procedure for screening asymptomatic persons because no manufacturer has produced convincing data and/or an application to the agency for such backing.1
To date, none of the national professional medical societies nor any federal or public health agencies have endorsed WBS as a safe, effective screening tool. Organizations that make it a policy not to recommend WBS as a screening procedure include the American College of Radiology, the American College of Cardiology and the associated American Heart Association, the FDA, the Agency for Healthcare Research and Quality and its preventive services unit (the United States Preventive Services Task Force), the Health Physics Society, and the American Association of Physicists in Medicine.1
Screening tests
An effective screening test must be safe and cost-effective and must have a very high degree of sensitivity and specificity for determining the presence or absence of preclinical or early-stage disease in asymptomatic persons. Furthermore, the disease must be responsive to treatment. That is, it must be possible to reduce morbidity and/or mortality through treatment if the disease is found early for screening to be justified.
Clinical impact
No available data indicate that WBS can significantly affect the outcome of any disease state.1,2 Additionally, screening for multiple disease states simultaneously with a single test may well increase the rates of both false-positive and false-negative findings.2
Problems with WBS
Depending on the scanner, the operator, the length of the scan, the radiation level, and the patient's body mass index and sensitivity to radiation, a single WBS procedure might provide radiation exposure that is several hundred times that of a chest film.3,4 WBS performed annually for 30 years could increase a person's overall cancer mortality risk by approximately 2%.5 The data regarding cost-effectiveness are even scarcer than those on the effectiveness of WBS as a screening tool. WBS does not appear to be cost-effective for screening.2,3,6
A Harvard mathematical model calculated the false-positive rate of WBS to be approximately 90%.6 False-positive findings cause patient anxiety and can lead to additional procedures. No adequate data exist to estimate the false-negative rates of WBS. False-negative findings can be inappropriately reassuring and prevent a patient from undergoing proven age- and risk-appropriate screening examinations.
There may be more false-negative findings with WBS because small lesions are often missed if contrast media are not utilized.3 Furthermore, when many abdominal cancers are diagnosed—even when contrast is used—they are often so advanced that effective treatment is not possible.3 Finally, WBS may detect insignificant abnormalities that would cause the patient undue psychological distress and result in serial scanning procedures.7
Bottom line
Because of the risks associated with radiation exposure and the inadequacies of CT, the future of WBS, if it has one, probably lies with MRI. Until further data become available, no evidence supports recommending any type of WBS to patients.
The author is the owner of Physician Assistant Medical Services (P.A.M.S.) in Williamsburg, WV, a past president of the AAPA, and president elect of the Society for the Preservation of Physician Assistant History. She has indicated no relationships to disclose relating to the content of this article.
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REFERENCES
1. Food and Drug Administration. Whole body scanning using computed tomography (CT). 2002. Available at: http://www.fda.gov/cdrh/ct/. Accessed February 8, 2006.
2. Hunink MG, Gazzelle GS. CT screening: a trade-off of risks, benefits, and costs. J Clin Invest. 2003;111(11):1612-1619.
3. Food and Drug Administration. Whole body scanning using computed tomography (CT): whole body CT screening—should I or shouldn't I get one? 2002. Available at: http://www.fda.gov/cdrh/ct/screening.html. Accessed February 8, 2006.
4. Food and Drug Administration. Whole body scanning using computed tomography (CT): what are the radiation risks from CT? 2005. Available at: http://www.fda.gov/cdrh/ct/risks.html. Accessed February 8, 2006.
5. Brenner DJ, Elliston CD. Estimated radiation risks potentially associated with fullbody CT screening. Radiology. 2004;232(3):735-738.
6. Beinfeld MT, Wittenberg E, Gazelle GS. Cost-effectiveness of whole-body CT screening. Radiology. 2005;234(2):415-422.
7. Stanley RJ. Inherent dangers in radiologic screening. AJR Am J Roentgenol. 2001; 177(5):989-992.