The advent of the CT scanner in the early 1970s removed much, if not all, of the morbidity and discomfort previously associated with diagnostic imaging studies. Throughout the 1970s and 1980s, advances in CT technology allowed radiologists to scan "better and faster." The professional fee for reading a CT study was higher than for reading a radiograph, an uncontroversial policy. But estimating the technical fee for using CT (and later MR) raised problems that would persist for at least 30 years. Consistently generous technical fees created potential incentives to create and fill advanced imaging capacity and contributed to the emerging problem of health care inflation.

During the first decade of the 21st century, the imaging bubble began to burst. The combination of digitized images, the DICOM standard, and affordable PACS sharply increased radiologists' productivity but also allowed an imaging study to be read from anywhere, creating the field of teleradiology and increased competition for radiologists. Increasing numbers of insurers contracted with radiology benefits managers to help control radiology utilization, and the Deficit Reduction Act of 2005 mandated spending cuts across the government. Consolidation of multiple Current Procedural Terminology codes and the reassessment of calculations used to estimate the utilization of a CT or an MRI scanner exerted additional downward pressure on radiology reimbursements. All of these factors, combined with more radiologists' completing residency and the delayed retirement of older radiologists after the 2008 financial crisis, brought the imaging bubble to an end.

In this four-part work, the authors review the economic history of how radiologists are paid, from the fight for independent billing in the 1960s to the impact of advanced imaging technologies on radiologists' incomes in the 1980s to the "bubble years" of the 1990s and to the end of the bubble in the first decade of the 21 century. The authors begin in this first part with the connections among a radiologist from Arkansas, a congressman, and the passage of Medicare, the program that gave radiologists the right to bill independently and gave the federal government a big role in health care spending.

With the collapse of the Clinton health care reforms, advanced imaging entered an economic bubble. Between 1995 and 2006, the number of CT and MRI studies almost tripled, from 21 million to 62 million and from 9.1 to 26.6 million, respectively. The increase reflected increases in both the number of scanners and the number of scans generated per CT or MRI scanner. Without restrictions, the profits generated by CT and MR ownership inevitably spread from hospitals first to imaging centers and later to individual physicians' offices and led to potential for conflict of interest and self-referral. During this time, the increase in radiologists' efficiency was fueled by the conversion from "film" to digitized images and PACS. In conjunction with increased volume and efficiency, radiologists' compensation increased throughout the 1990s.

PURPOSE: Medical imaging is a large and growing component of health care expenditures. To better understand some of the determinants of imaging ordering behavior, the authors analyzed the effect of differential capacity on the imaging workup of patients with acute nonhemorrhagic stroke. METHODS: All patients at a US teaching hospital and a two-campus Canadian teaching hospital between 2001 and 2005 discharged with diagnoses of acute nonhemorrhagic stroke were identified. Billing data were linked with clinical information systems to identify all imaging studies performed, comorbidities, and patient disposition. RESULTS: Nine hundred eighteen patients at the US hospital and 1,759 patients at the Canadian hospital were included. Patients were similar in age and distribution of comorbid illnesses. The rate of MRI scans at the US hospital was more than twice that at either of the Canadian hospitals (95.75 scans per 100 patients vs 41.39 scans per 100 patients). The length of stay was significantly shorter and the inpatient mortality rate significantly lower at the US hospital compared with the Canadian hospital. A multivariate regression analysis demonstrated that only patient age and site (US vs Canada) were significant predictors of MRI use, controlling for patient gender, comorbidities, and use of anticoagulants. CONCLUSIONS: Scanning utilization varied at hospitals with differential access to scanning technologies. There was less frequent use of MRI scanning at hospitals with limited access to this modality. Patient and health system factors are important considerations when interpreting the mechanisms for this variation, its importance, and the potential relationship of imaging use with patient outcomes. rights reserved.