Stanford Study Examines Value of Imaging Technologies

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James R. Brennan

November 1, 2008

5 Min Read
Stanford Study Examines Value of Imaging Technologies

Baker: Imaging under study.

The availability and use of magnetic resonance imaging (MRI) has soared since its introduction in the 1980s and, along with other forms of imaging technology such as computed tomography units (CT), has led to major increases in costs for Medicare and other payers.

Whether society ultimately gets its money's worth for expanded imaging availability is a multifaceted question, one that researchers at Stanford University sought to answer in a study published in the November issue of Health Affairs.1 The study correlated Medicare claims data with U.S. censuses that recorded the number and location of MRI and CT facilities and units at four points in time.

The research team, led by Laurence C. Baker, PhD, professor of health research and policy at Stanford, says that there are clear relationships between the availability of imaging units and their use. The team found that each additional MRI unit is associated with 733 more MRI procedures per year among Medicare beneficiaries age 65 and older, adding $550,000 to annual Medicare costs. Each additional CT unit led to 2224 more procedures per year, resulting in $685,000 in Medicare costs.

According to Baker, the high costs associated with imaging technologies raise concern about whether widespread availability is justified. But the value of the technologies, he says, depends on whether the imaging procedures lead to improved health outcomes for patients, or reduce the need for more expensive or invasive diagnostic tests.

Studying the use of imaging technologies can help researchers determine how to evaluate costs and benefits related to many other medical technologies. “Imaging is an area where capabilities are changing rapidly and where treatments can be quite costly, which is not unlike some other areas in medicine,” says Baker. “In all areas of medicine, we need to get the evidence and develop paradigms that will help us take advantage of the tremendous potential of new approaches to diagnosis and treatment, while still being sensitive to the costs that indiscriminant use can generate.”

According to Baker, imaging use has important similarities to other types of diagnostics, where researchers have to pay attention to the potential for new technologies to be disseminated very widely and adopted very quickly. “Sometimes expanding use is beneficial—we can screen more people for significant disease, for example. But sometimes, we can also get ahead of the evidence, and then we have to be careful,” he says. “Therapeutic procedures can also see rapid expansion, but can be more constrained by the number of patients needing treatment.”

As part of the study, the Stanford team looked at how CT angiography (CTA) scans are used to diagnose abdominal aortic aneurysms—which can cause serious health problems if untreated. The study found that CTA has emerged as an effective alternative to catheter angiography, an invasive test that carries a range of complications for patients.

The report calculates significant expansion in the use of CTA, noting that “for every 100 new abdominal CTA users, about 68 are people who would not have previously received either a CTA or a catheter angiography.”

In some cases, expanded use of CTA represents a new technology replacing an older one. “For every 100 CT angiography scans of the abdomen, there are about 15 less catheter angiographies now being used,” Baker said.

In either case, the use of CTA was found to provide benefits to patients. “Because of its availability, we found that the new CTAs are being performed on patients that would not have received any diagnosis in the past,” said Baker. “The value here is the value of information and what can be ruled out.”

Baker notes that the report's calculations of cost and benefit might be different for payers and populations other than the government-served Medicare population “On the benefits side, at the level of the healthcare system, the calculations seem like they would be substantially similar,” says Baker. “We care about whether health outcomes are better and whether patients (or their families, friends, and community members) benefit in other ways.

“But these discussions could have some different nuances that would depend on the payers. On the cost side, Medicare and private payers compensate providers in different ways, so there might be differences in the monetary flows. Medicare is a public program, which can raise some of its own issues,” he adds.

The Stanford report points the way toward additional research to identify the benefits of using advanced imaging technologies. “It seems likely that key benefits of expanded imaging use will in some cases include improvements in measurable health outcomes, but will frequently include other, perhaps less tangible, types of benefits,” says the report's conclusion. “At one level, this raises a set of analytic questions about how these benefits could be measured and incorporated into analyses. At another, it may raise important questions about the extent to which the healthcare system should pay for benefits other than improvements in objective health measures.”

Baker says that many of the same basic research issues apply to both diagnostic and therapeutic technologies. “Developing new therapies has been beneficial for patients over the years, and some of these are quite expensive. Some of the benefits from new therapies accrue from better health outcomes, and some accrue from less tangible sources, like in imaging,” he says. “We need evidence and policy approaches that recognize this for therapies, too, and work to balance the sometimes large benefits with the costs they can generate.”

The Stanford team is now engaged in studies that attempt to track benefits and costs for some specific populations, such as those with suspected carotid artery disease. “We hope to have something ready to make public pretty soon, but are working with journals on getting that work accepted for publication,” says Baker.

The Stanford research was funded by the Institute for Health Technology Studies (Washington, DC), a nonprofit research and educational organization supporting independent analyses of the economic and social effects of diagnostic and therapeutic medical devices. Visit for more information.


1. LC Baker, SW Atlas, and CC Afendulis, “Expanded Use of Imaging Technology and the Challenge of Measuring Value,” Health Affairs 27, no. 6 (2008 [cited 13 November 2008]): 1467–1478; available from Internet:

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