MONDAY, Nov. 10 (HealthDay News) -- The use of MRI and CT scanners in the United States has more than doubled since 1995. But that hasn't necessarily resulted in better health care or fewer deaths, according to a study by researchers at Stanford and Harvard universities.

The researchers analyzed Medicare claims data and found that the number of MRI procedures per 1,000 beneficiaries was 0.3 in 1985, 50 in 1995 and 173 in 2003. The number of CT procedures increased from 235 per 1,000 beneficiaries in 1995 to 547 per 1,000 in 2005.

Each new CT scanner led to an additional 2,224 CT procedures per year, adding $685,000 to the nation's yearly Medicare bill. Each new MRI unit led to an additional 733 MRI procedures per year, adding $550,000 to annual Medicare costs.

Increased use of scanning technology can improve health results for some patients and can also produce less tangible benefits, such as providing patients with more information about a disease or condition. But the researchers said it's unclear whether these less tangible benefits justify the costs of more machines and tests.

As an example, the researchers said they looked at the use of CT scans to diagnose conditions affecting the abdominal aorta, particularly abdominal aortic aneurysms. While increased use of CT scans resulted in a few more patients being treated, the change was small. This example highlights the challenges of measuring costs and benefits from increased use of imaging technologies, said the researchers, who added that further study is needed.

The study was published in the November-December edition of the journal Health Affairs, a special issue that examines the costs and benefits of increased use of new medical technologies.

"We pay for a lot of things that make us happier, but don't necessarily make us healthier. We need to improve our ability to measure the costs and benefits of the dramatic rise in diagnostic imaging we've seen in the past decade," study author Laurence Baker, of Stanford University, said in a journal news release.

Another study in the same issue of Health Affairs found that from 1997 to 2006, the use of almost every type of imaging technology increased, including CT, MRI, ultrasound, nuclear medicine, X-rays and arteriography.

The analysis of patients enrolled in a large, nonprofit health-care system in Washington state also found that annual imaging costs more than doubled from $229 per enrollee in 1997 to $463 per enrollee in 2006.

When they studied specific technologies, Rebecca Smith-Bindman of the University of California, San Francisco, and colleagues found that:

• Use of CT, MRI and ultrasound combined rose from 260 examinations per 1,000 enrollees in 1997 to 478 per 1,000 in 2006.
• CT imaging more than doubled from 81 to 181 exams per 1,000 enrollees.
• MRI imaging more than tripled from 22 to 72 exams per 1,000 enrollees.

Increases in medical imaging occurred across all patient groups, meaning that efforts to reduce the use of medical imaging can't focus on a single group according to age, sex or disease, the researchers said.

They wrote that it's "difficult to identify which imaging tests are most beneficial, and strategies that rely on financial disincentives tend to decrease imaging across the board, instead of selectively reducing unnecessary imaging."

More focus should be put on studying the cost-effectiveness of imaging tests and the effect on patient care so that policy makers, payers and providers can better determine how best to use these tests, the researchers recommended.

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