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 for 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 were summarized using descriptive statistics and 95% CIs. Results: Projected annual energy consumption per scanner ranged from 82.7 to 171.1 MW-hours, with 72%-91% defined as nonproductive. Power draws for each mode were measured as 6.4 kW & PLUSMN; 0.1 (SD; power-save mode), 7.3 kW & PLUSMN; 0.6 to 9.7 kW & PLUSMN; 0.2 (off), 9.5 kW & PLUSMN; 0.9 to 14.5 kW & PLUSMN; 0.5 (idle), 17.3 kW & PLUSMN; 0.5 to 25.6 kW & PLUSMN; 0.6 (prepared-to-scan mode), and 28.6 kW & PLUSMN; 8.6 to 48.3 kW & PLUSMN; 11.8 (scan mode). Switching MRI units from idle to off mode for 12 hours overnight reduced power consumption by 25%-33%, translating to a potential annual savings of 12.3-21.0 MW-hours, $1717-$2943, and 8.7-14.9 metric tons of carbon dioxide (CO2) equivalent (MTCO2eq). The power-save mode further reduced consumption by 22%-28% compared with off mode, potentially saving an additional 8.8-11.4 MW-hours, $1226-$1594, and 6.2-8.1 MTCO2eq per year for 12 hours overnight. Implementation of a power-save mode for 12 hours overnight in all outpatient MRI units in the United States could save U.S. health care 58 863.2-76 288.2 MW-hours, $8.2-$10.7 million, and 41 606.4-54 088.3 MTCO2eq. Conclusion: Powering down MRI units made radiology departments more energy efficient and showed substantial sustainability and cost benefits.& COPY; RSNA, 2023
