Utilization of radiology services in the United States: levels and trends in modalities, regions, and populations.

PURPOSE: To assess the most recent available data for levels and trends in utilization of radiology procedures across populations, modalities, and geographic areas.
MATERIALS AND METHODS: Aggregated claims data from Medicare enrollees for all radiology procedures and from the Medical Expenditure Panel Survey (MEPS), a nationally representative survey of almost 25 000 Americans, for some radiology procedures, were used to calculate population-based utilization for the relevant age groups. Limited private insurer data also were obtained. All radiology utilization was measured and reported, irrespective of provider specialty. Average levels and percentiles of utilization were measured according to modality, and average annual rates of increase in utilization were compared across modalities, data sources, and regions. Rates of increase in utilization according to modality and state were compared for correlation with state characteristics and initial utilization levels.
RESULTS: In 2001, 4176 diagnostic and 274 therapeutic radiology procedures were performed per 1000 Medicare non-managed care enrollees. Nearly one-half of diagnostic procedures (n=2057) involved radiography. The other half involved computed tomography (CT) (n=391), magnetic resonance (MR) imaging (n=114), ultrasonography (US) (n=921), interventional radiology (n=215), mammography (n=221), and nuclear medicine (n=249). On average, between 1998 and 2001, utilization per Medicare enrollee increased 16% per year for MR imaging and 7%-15% per year for CT, US, interventional radiology, and nuclear medicine, while that for radiography increased 1% per year. The proportion of diagnostic radiology procedures performed in ambulatory settings increased from 62% in 1992 to 68% in 2001. There was wide variation across states in utilization by Medicare enrollees. State totals for diagnostic radiology were 3038 in the 10th percentile and 4573 in the 90th percentile. In 1999, MEPS reported average utilization in ambulatory settings as follows: 64 MR imaging, 102 US, 73 mammographic, 326 radiographic, and 43 radiation therapy procedures per 1000 persons (all ages) in the U.S. population.
CONCLUSION: Utilization of high-technology modalities increased rapidly, while that of radiography was relatively stagnant. Variation in utilization among states and census regions was substantial.