Excess Greenhouse Gas Emissions Associated With Inappropriate Medical Imaging in the US Medicare Part B Population From 2017 to 2021.

Introduction: Medical imaging is a source of greenhouse gas emissions, and inappropriate use results in low-value, excess imaging. The environmental impact of low-value imaging has not been quantified.

Objective: This study seeks to estimate excess greenhouse gas (GHG) emissions associated with inappropriate imaging in metric kilotons (kT) of carbon dioxide equivalents (CO2e) from the Medicare Part B population from 2017 to 2021.

Materials and methods: Using the Harvey L. Neiman Health Policy Institute 2017 to 2021 data on trends in imaging utilization for Medicare Fee-for-Service Beneficiaries and the 2014 RAND Corporation report on Medicare Imaging Demonstration, low-end and high-end estimates of average yearly GHG emissions from inappropriate examinations in Medicare Part B population were modeled for the four most-common imaging modalities (MRI, CT, radiography, and ultrasound) from the estimated number of inappropriate examinations per year and GHG emissions per modality.

Results: Of all imaging, 4% to 26% is estimated as inappropriate. Total inappropriate Medicare imaging examinations were estimated to have produced an average of 3.55 to 129.2 kT CO2e per year during the entire 5-year period, with MRI and CT accounting for the greatest proportion (0.621-33.8 kT and 1.24-64.8 kT, respectively); 3.55 to 129.2 kT CO2e approximates to the GHG produced by the yearly electricity of a town of 2,000 to 72,000 people, respectively.

Conclusion: Our results demonstrate that substantial excess GHG emissions arise from inappropriate imaging, particularly MRI and CT. These data support the need to reduce low-value imaging and adherence to appropriate use criteria.