Imaging utilization rises where radiology presence drops

Rates of diagnostic imaging utilization varied by more than 56% across the 10 Medicare regions of the U.S., according to a study presented Wednesday. The regions with the highest utilization had the lowest percentage of imaging services provided by radiologists.

The study looked at trends in noninvasive imaging services provided to Medicare patients using the Medicare Part B fee-for-service database. The survey also analyzed trends over a five-year period ending in 2006.

In 2006, utilization rates per 1000 Medicare beneficiaries ranged from a high of 4532 in the Atlanta region to a low of 2901 in the Seattle region. Radiologists' share of the imaging services provided ranged from 69% in the Boston region to a low of 58% in the Atlanta region.

Plotting the radiologist share against the overall utilization rates showed generally that the higher the utilization rate, the lower the percentage of radiologists providing the services, said Dr. Vijay Rao, chair of radiology at Thomas Jefferson University, who presented the data. The Seattle region, for example, had the lowest utilization rate and lowest percentage of imaging provided by nonradiologists.

Rates of growth in diagnostic imaging ranged from 20% in the New York region to 8% in the Seattle region, Rao said. In all regions of the country, utilization growth is higher among cardiologists than among radiologists or other imaging providers.

During a question and answer session, Rao said more analysis is needed before drawing firm conclusions about the causes of imaging utilization variation and growth.

"One could argue it's all self-referral," she said. "On the other hand, it could be related to density of population, the adoption of technology, or that the radiologists can't meet the demand for imaging and the nonradiologists are filling in."