Upper left bar graph showing numbers of services during the study period. All imaging services are depicted in light blue bars and subdivided into "heart imaging" (red bars) and "non-heart imaging" services (imaging services not involving evaluation of the heart [yellow bars]). Heart imaging services are further subdivided into echocardiography services (dark blue bars) and "other heart imaging" (including nuclear, computed tomography, and magnetic resonance imaging of the heart but excluding echocardiography services [green bars]). The same format is used in the 2 lower panels. Upper right line graph demonstrating total number of Medicare enrollees during each year of the study period. Lower left bar graph showing the total number of professional service relative value units (RVUs) during the years of the study, expressed in constant 2005 RVU values and calculated by applying professional service RVUs (Current Procedural Terminology modifier –26) to every service except technical-component-only services; this excludes all technical components and costs of supplies such as imaging agents and isotopes. Lower right bar graph showing total Medicare allowed charges during the years of the study.

The frequencies with which these services were provided in various sites of service are shown for the years 1999 and 2004. IDTF = independent diagnostic testing facility; Inpatient = hospital inpatient; Office = physician's office; OPD = hospital outpatient department.

Scatter graph of per capita use of echocardiography imaging services in 2004, by state (vertical axis), against the prevalence per capita of congestive heart failure (CHF) in each state (horizontal axis). Use data were taken from the Medicare Part B Physician/Supplier Procedure Summary Master File (see Methods section), total Medicare fee-for-service enrollment was taken from Medicare's state/county managed care market penetration report, and CHF prevalence was taken from the Centers for Medicare and Medicaid Services Hierarchical Coexistent Conditions risk adjustment model. Enrollment was adjusted to match carrier service areas.