Recent trends in utilization rates of noncardiac thoracic imaging: an example of how imaging growth might be...

To study trends in the utilization of the various noncardiac thoracic imaging modalities in the Medicare population in recent years and to compare the roles of radiologists and nonradiologist physicians.

The Medicare Part B databases for 1996 through 2005 were reviewed. All Current Procedural Terminology, Fourth Edition, codes pertaining to noninvasive imaging of noncardiac thoracic structures were selected and grouped into 5 categories: chest radiography (CXR), chest computed tomography (CT)/computed tomographic angiography (CTA), noncardiac radionuclide scans, ultrasound, and magnetic resonance imaging/magnetic resonance angiography. Utilization rates per 1,000 Medicare beneficiaries were calculated. Medicare physician specialty codes were used to ascertain utilization by radiologists compared with nonradiologist physicians. Trends over the 9-year period were studied.

In 1996, a total of 1,044.1 noncardiac thoracic imaging examinations were performed per 1,000 Medicare beneficiaries, increasing to 1,051.6 in 2005 (+1%). In the largest category, CXR, the utilization rate dropped from 995.2 in 1996 to 941.5 in 2005 (-5%). The radionuclide scan utilization rate also dropped, from 16.9 in 1996 to 8.3 in 2005 (-51%). By contrast, the chest CT/CTA utilization rate increased from 30.9 in 1996 to 99.7 in 2005 (+223%). The use of magnetic resonance imaging/magnetic resonance angiography and ultrasound in the thorax was minimal. In 2005, radiologists performed 91% of CXR studies, 97% of chest CT/CTA studies, and 94% of noncardiac chest radionuclide scans.

The overall utilization rate of noncardiac chest imaging in recent years has increased only minimally. Within the various categories, there has been a decline in CXR utilization and a substantial decline in radionuclide scan utilization. However, there has been a considerable increase in the utilization of chest CT/CTA. Radiologists strongly predominate in all aspects of noncardiac thoracic imaging. This seems to be a pattern in which the use of a newer and better technology, CT or CTA, gradually replaces older ones and overall utilization rates remain relatively flat. One reason for this seems to be the lack of major involvement by nonradiologist physicians who might be in a position to self-refer. It is in contradistinction to cardiac imaging, in which the utilization of radionuclide scans and echocardiography has sharply increased among cardiologists. These data suggest that utilization rates in imaging might be kept under control by eliminating the opportunity for self-referral.