A new Harvey L. Neiman Health Policy Institute study found that radiologists interpreted 72.1% of all imaging studies for Medicare fee-for-service beneficiaries in 2022, with the remaining 27.9% performed by other types of clinicians.

Market share varied by imaging modality; radiologists interpreted 97.3% of CT, 91% of MR, 76.6% of radiology/fluoroscopy, 50.9% of nuclear medicine, and just 33.9% of ultrasound.

The research, published in the Journal of the American College of Radiology was based on 123 million Medicare Part B imaging claims in 2022.

For noncardiac imaging, the study found that radiologists interpreted nearly all imaging in the hospital outpatient, inpatient, and emergency department settings. Even in the office setting, radiologists interpreted a majority of noncardiac advanced imaging CT, MR, and nuclear medicine exams, but just 43.1% of radiology/fluoroscopy and 29.2% of ultrasound exams.

“There are economic benefits to non-radiologists that likely contribute to their majority market share of radiography/fluoroscopy and ultrasound imaging. These providers have financial incentives for self-referral of imaging,” stated Eric Christensen, research director at the Neiman Institute. “The Stark Law, which was designed in part to prohibit self-referral of imaging to facilities in which the referring physician had a financial interest, have largely been ineffective. The literature shows that even after the passage of the Stark Law, self-referring non-radiologists ordered 1.2 to 6.4 times more imaging studies than those who do not self-refer.”

“Non-radiologists have likely been more successful with capturing market share with radiography/fluoroscopy and ultrasound than with advanced modalities because imaging volume from their practice’s patients alone may be sufficient for a positive return on investment for providing these services” stated coauthor Dr. Jeffrey Newhouse, professor emeritus of Radiology, Columbia University Medical Center. “However, advanced imaging involves substantially higher capital and operational costs, making the economics impractical for most practices.”

The study found that radiologist market share also varied by the focus body region, and in particular for cardiac imaging. For noncardiac imaging, radiologists interpreted 97.6% of CT, 91.4% of MR, 95.6% of nuclear medicine, 76.6% of rad/fluoro, and 53.0% of ultrasound. In contrast, radiologists’ share of cardiac imaging was 67.6% of CT, 42.2% of MR, 11.8% of nuclear medicine, and 0.4% of ultrasound.

“Cardiologists interpret most cardiac imaging, and a greater share than radiologists for all modalities except cardiac CT” stated Christensen. “Cardiology is the only non-radiology specialty that interprets a large percentage of advanced imaging—CT, MR, and nuclear medicine — but only cardiac imaging.”

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