Benefits Questioned as Imaging Test Use Soars; New CT, MRI Research Points to Radiation Risks, Costs to Health Care System

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Byline: Jon Bardin

LOS ANGELES | The use of CTs, MRIs and other advanced medical imaging tests has soared over the last 15 years, according to new research that raises questions about whether the benefits of all these scans outweigh the potential risks from radiation exposure and costs to the health care system.

An examination of data from patients enrolled in six large health maintenance organizations found that doctors ordered CT scans at a rate of 149 tests per 1,000 patients in 2010, nearly triple the rate of 52 scans per 1,000 patients in 1996. MRI use nearly quadrupled during the period, jumping from 17 to 65 tests per 1,000 patients, according to results published in Wednesday's edition of the Journal of the American Medical Association.

These and other tests have meant that more patients have absorbed more ionizing radiation as part of their medical care. The proportion of patients in the study who had any amount of radiation exposure - driven by the use of CTs - rose from 28.5 percent in 1996 to 36.2 percent in 2010; among them, their average exposure jumped from 4.8 millisieverts to 7.8 millisieverts. At the top end of the spectrum, the proportion of patients in the study who got radiation at high or very high levels rose from 1.8 percent to 3.9 percent.

"We've become victims of our own technology," said George Bisset, chief of pediatric radiology at Texas Children's Hospital in Houston and president of the Radiological Society of North America.

Advances in imaging technology have allowed doctors to peer inside the body with striking resolution. Computed tomography, or CT, scans combine a series of X-rays into a detailed three-dimensional image. Magnetic resonance imaging machines detect energy emitted by hydrogen atoms in the body and convert that into pictures. Both tests can reveal blockages in arteries, bleeding in the brain, tumors and other life-threatening conditions.

Although MRIs do not use ionizing radiation, CTs do, and that can damage the DNA in cells and lead to mutations that cause cancer. A number of recent studies have linked increases in medical imaging to higher rates of radiation-induced cancers, including a report last week in Lancet that showed a correlation between CT scans in children and their subsequent risk of developing brain tumors or leukemia.

And both kinds of tests are expensive. Advanced imaging adds about $100 billion to U.S. medical bills each year, said study leader Rebecca Smith-Bindman, a radiologist and epidemiologist at the University of California, San Francisco.

There is widespread agreement in the medical community that imaging tests are overused, particularly CT scans. In April, the American Board of Internal Medicine released a report that asked doctors from numerous medical specialties to list five procedures they felt were used too much. …