Ecodesign and Operational Strategies to Reduce the Carbon Footprint of MRI for Energy Cost Savings.

Background Radiology is a major contributor to health care's climate footprint due to energy-intensive devices, particularly MRI which uses the most energy. Purpose To determine the energy, cost, and carbon savings that could be achieved through different scanner power management strategies. Materials and Methods In this retrospective evaluation, four outpatient MRI scanners from three vendors were individually equipped with power meters (1-Hz sampling rate). Power measurement logs were extracted over 39 days. Data were segmented into off, idle, prepared-to-scan, scan, or power-save modes for each scanner. Energy, cost (assuming a mean cost of $0.14 per kilowatt hour), and carbon savings were calculated for the lowest scanner activity modes. Data was summarized using descriptive statistics and 95% confidence intervals. Results Projected annual energy consumption per scanner ranged from 82.7-171.1 megawatt-hours (MWh), with 72-91% defined as nonproductive. Power draws for each mode were measured as 6.4 ± 0.1 kW (power-save), 7.3 ± 0.6 kW to 9.7 ± 0.2 kW (off), 9.5 ± 0.9 to 14.5 ± 0.5 kW (idle), 17.3 ± 0.5 to 25.6 ± 0.6 kW (prepared-to-scan), and 28.6 ± 8.6 to 48.3 ± 11.8 kW (scan). Switching MRIs from idle to off mode for 12 overnight hours reduced power consumption by 25-33%, translating to a potential annual savings of 12.3-21.0 MWh, $1717-$2943 U.S. dollars, and 8.7-14.9 metric tons of CO2-equivalent (MTCO2eq). The power-save mode further reduced consumption by 22-28% compared to off mode, potentially saving an additional 8.8-11.4 MWh, $1,226-$1,594 U.S. dollars, and 6.2-8.1 MTCO2eq per year for 12 hours overnight. Implementation of a power-save mode for 12 hours overnight on all U.S. outpatient MRI in the U.S. could save U.S. health care 58,863.2-76,288.2 MWh, $8.2-$10.7 million U.S. dollars, and 41,606.4-54,088.3 MTCO2eq. Conclusion Powering down MRIs can make radiology departments more energy-efficient and gain substantial sustainability and cost benefits. See also the editorial by Vosshenrich and Heye.