Environmental Sustainability and MRI: Challenges, Opportunities, and a Call for Action

The environmental impact of magnetic resonance imaging (MRI) has recently come into focus. This includes its enormous demand for electricity compared to other imaging modalities and contamination of water bodies with anthropogenic gadolinium related to contrast administration. Given the pressing threat of climate change, addressing these challenges to improve the environmental sustainability of MRI is imperative. The purpose of this review is to discuss the challenges, opportunities, and the need for action to reduce the environmental impact of MRI and prepare for the effects of climate change. The approaches outlined are categorized as strategies to reduce greenhouse gas (GHG) emissions from MRI during production and use phases, approaches to reduce the environmental impact of MRI including the preservation of finite resources, and development of adaption plans to prepare for the impact of climate change. Co-benefits of these strategies are emphasized including lower GHG emission and reduced cost along with improved heath and patient satisfaction. Although MRI is energy-intensive, there are many steps that can be taken now to improve the environmental sustainability of MRI and prepare for the effects of climate change. On-going research, technical development, and collaboration with industry partners are needed to achieve further reductions in MRI-related GHG emissions and to decrease the reliance on finite resources. LEVEL OF EVIDENCE: 5 TECHNICAL EFFICACY: Stage 6.

Environmental Sustainability and AI in Radiology: A Double-Edged Sword

According to the World Health Organization, climate change is the single biggest health threat facing humanity. The global health care system, including medical imaging, must manage the health effects of climate change while at the same time addressing the large amount of greenhouse gas (GHG) emissions generated in the delivery of care. Data centers and computational efforts are increasingly large contributors to GHG emissions in radiology. This is due to the explosive increase in big data and artificial intelligence (AI) applications that have resulted in large energy requirements for developing and deploying AI models. However, AI also has the potential to improve environmental sustainability in medical imaging. For example, use of AI can shorten MRI scan times with accelerated acquisition times, improve the scheduling efficiency of scanners, and optimize the use of decision-support tools to reduce low-value imaging. The purpose of this Radiology in Focus article is to discuss this duality at the intersection of environmental sustainability and AI in radiology. Further discussed are strategies and opportunities to decrease AI-related emissions and to leverage AI to improve sustainability in radiology, with a focus on health equity. Co-benefits of these strategies are explored, including lower cost and improved patient outcomes. Finally, knowledge gaps and areas for future research are highlighted.

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.

Radiology Environmental Impact: What Is Known and How Can We Improve?

The healthcare sector generates approximately 10% of the total carbon emissions in the United States. Radiology is thought to be a top contributor to the healthcare carbon footprint due to high energy-consuming devices and waste from interventional procedures. In this article, we provide a background on Radiology's environmental impact, describe why hospitals should add sustainability as a quality measure, and give a framework for radiologists to reduce the carbon footprint through quality improvement and collaboration.

Association Between the Frequent Use of Perineal Talcum Powder Products and Ovarian Cancer: a Systematic Review and Meta-analysis

BACKGROUND

Risk of ovarian cancer in women with frequent perineal talcum powder product is not well understood. Prior systematic reviews focused on ever use. The purpose of this study is to estimate the association between frequent (at least 2 times per week) perineal talcum powder use and ovarian cancer.

METHODS

A systematic review and meta-analysis was conducted according to meta-analysis of observational studies in epidemiology guidelines. Study protocol was prospectively registered at PROSPERO (registration number CRD42020172720). Searches were performed in PubMed, Embase, Web of Science, and Cochrane Central Register of Controlled Trials databases from their inception to August 2, 2021. Case-control and cohort studies were included if they reported frequent perineal talcum powder use and an adjusted odds ratio or hazard ratio for ovarian cancer. Review for inclusion, data extraction, and quality assessment (using the Newcastle-Ottawa Scale [NOS]) were performed independently by two reviewers. Pooled adjusted odds ratios with 95% confidence intervals were generated from the random effects model. Heterogeneity was quantified with I² statistic. Funnel plot and Eger's test were performed to assess publication bias. Subgroup and sensitivity analyses were performed for testing the robustness of the overall findings.

RESULTS

Initial database searches returned 761 unique citations and after review, eleven studies describing 66,876 patients, and 6542 cancers were included (Cohen's κ = 0.88). Publication quality was high (median NOS = 8, range: 4 to 9). Frequent talcum powder use was associated with an elevated risk of ovarian cancer (adjusted pooled summary odds ratio 1.47 (95% CI 1.31, 1.65, P<0.0001). There was no evidence of bias and low heterogeneity (I²= 24%, P=0.22). There was no meaningful difference limiting analysis to publications with a NOS quality score of 8 or 9 or limiting studies based on study design.

CONCLUSIONS

This review suggests an increased risk of ovarian cancer associated with frequent perineal powder exposure of 31-65%.

Patient Preferences for Hepatocellular Carcinoma Surveillance Parameters

BACKGROUND AND AIMS

Professional societies recommend abdominal ultrasound (US) with or without alpha fetoprotein (AFP) for hepatocellular cancer (HCC) surveillance; however, there are several emerging surveillance modalities, including abbreviated MRI and blood-based biomarker panels. Most studies have focused on provider perspectives for surveillance logistics, but few have assessed patient preferences. We aimed to measure preferences among patients with cirrhosis regarding HCC surveillance modalities.

METHODS

We conducted a choice-based conjoint survey to patients with cirrhosis at four institutions. Participants were provided 15 scenarios in which they were asked to choose surveillance modalities based on five test attributes: benefits, i.e. sensitivity for early HCC (range: 35-95%), physical harm, i.e. false positives requiring additional testing (range: 10-40%), financial harm, i.e. out-of-pocket costs (range: $10-100), test logistics and convenience, i.e. duration of testing (range: 10-60 min). Hierarchical Bayes discrete choice conjoint analysis was used to derive attribute importance, and preference shares were determined by simulation.

RESULTS

In total 91% (182/199) of approached patients consented to participate in the study and 98% (n=179) successfully completed the survey. Surveillance benefits (importance: 51.3%, 95%CI: 49.0-53.4%) were valued more than risk of physical harm (importance: 7.6%, 95%CI 7.0-8.2%), financial harm (importance: 15.2%, 95%CI 14.0-16.3%), convenience (importance: 9.3%, 95%CI 8.5-10.1%) and test logistics (importance: 16.7%, 95%CI 15.4-18.1%). Based on simulations including all possible tests, patients preferred abbreviated MRI (29.0%), MRI (23.3%), or novel blood-based biomarkers (20.9%) to ultrasound alone (3.4%) or with AFP (8.8%).

CONCLUSIONS

Patients with cirrhosis prioritize early HCC detection over potential surveillance-related harms or inconvenience.

Intraobserver Variability in Bladder Cancer Treatment Response Assessment With and Without Computerized Decision Support

We evaluated the intraobserver variability of physicians aided by a computerized decision-support system for treatment response assessment (CDSS-T) to identify patients who show complete response to neoadjuvant chemotherapy for bladder cancer, and the effects of the intraobserver variability on physicians' assessment accuracy. A CDSS-T tool was developed that uses a combination of deep learning neural network and radiomic features from computed tomography (CT) scans to detect bladder cancers that have fully responded to neoadjuvant treatment. Pre- and postchemotherapy CT scans of 157 bladder cancers from 123 patients were collected. In a multireader, multicase observer study, physician-observers estimated the likelihood of pathologic T0 disease by viewing paired pre/posttreatment CT scans placed side by side on an in-house-developed graphical user interface. Five abdominal radiologists, 4 diagnostic radiology residents, 2 oncologists, and 1 urologist participated as observers. They first provided an estimate without CDSS-T and then with CDSS-T. A subset of cases was evaluated twice to study the intraobserver variability and its effects on observer consistency. The mean areas under the curves for assessment of pathologic T0 disease were 0.85 for CDSS-T alone, 0.76 for physicians without CDSS-T and improved to 0.80 for physicians with CDSS-T (P = .001) in the original evaluation, and 0.78 for physicians without CDSS-T and improved to 0.81 for physicians with CDSS-T (P = .010) in the repeated evaluation. The intraobserver variability was significantly reduced with CDSS-T (P < .0001). The CDSS-T can significantly reduce physicians' variability and improve their accuracy for identifying complete response of muscle-invasive bladder cancer to neoadjuvant chemotherapy.

Prospective multicenter assessment of patient preferences for properties of gadolinium-based contrast media and their potential socioeconomic impact in a screening breast MRI setting

Objective

It is unknown how patients prioritize gadolinium-based contrast media (GBCM) benefits (detection sensitivity) and risks (reactions, gadolinium retention, cost). The purpose of this study is to measure preferences for properties of GBCM in women at intermediate or high risk of breast cancer undergoing annual screening MRI.

Methods

An institutional reviewed board-approved prospective discrete choice conjoint survey was administered to patients at intermediate or high risk for breast cancer undergoing screening MRI at 4 institutions (July 2018–March 2020). Participants were given 15 tasks and asked to choose which of two hypothetical GBCM they would prefer. GBCMs varied by the following attributes: sensitivity for cancer detection (80–95%), intracranial gadolinium retention (1–100 molecules per 100 million administered), severe allergic-like reaction rate (1–19 per 100,000 administrations), mild allergic-like reaction rate (10–1000 per 100,000 administrations), out-of-pocket cost ($25–$100). Attribute levels were based on published values of existing GBCMs. Hierarchical Bayesian analysis was used to derive attribute “importance.” Preference shares were determined by simulation.

Results

Response (87% [247/284]) and completion (96% [236/247]) rates were excellent. Sensitivity (importance = 44.3%, 95% confidence interval = 42.0–46.7%) was valued more than GBCM-related risks (mild allergic-like reaction risk (19.5%, 17.9–21.1%), severe allergic-like reaction risk (17.0%, 15.8–18.1%), intracranial gadolinium retention (11.6%, 10.5–12.7%), out-of-pocket expense (7.5%, 6.8–8.3%)). Lower income participants placed more importance on cost and less on sensitivity (p < 0.01). A simulator is provided that models GBCM preference shares by GBCM attributes and competition.

Conclusions

Patients at intermediate or high risk for breast cancer undergoing MRI screening prioritize cancer detection over GBCM-related risks, and prioritize reaction risks over gadolinium retention.

Key Points

• Among women undergoing annual breast MRI screening, cancer detection sensitivity (attribute “importance,” 44.3%) was valued more than GBCM-related risks (mild allergic reaction risk 19.5%, severe allergic reaction risk 17.0%, intracranial gadolinium retention 11.6%, out-of-pocket expense 7.5%).

• Prospective four-center patient preference data have been incorporated into a GBCM choice simulator that allows users to input GBCM properties and calculate patient preference shares for competitor GBCMs.

• Lower-income women placed more importance on out-of-pocket cost and less importance on cancer detection (p < 0.01) when prioritizing GBCM properties.

Supplementary Information

The online version contains supplementary material available at 10.1007/s00330-021-07982-y.

Risk of Nephrogenic Systemic Fibrosis in Patients With Stage 4 or 5 Chronic Kidney Disease Receiving a Group II Gadolinium-Based Contrast Agent: A Systematic Review and Meta-analysis

IMPORTANCE

Risk of nephrogenic systemic fibrosis (NSF) to individual patients with stage 4 or 5 chronic kidney disease (CKD; defined as estimated glomerular filtration rate of <30 mL/min/1.73 m2) who receive a group II gadolinium-based contrast agent (GBCA) is not well understood or summarized in the literature.

OBJECTIVE

To assess the pooled risk of NSF in patients with stage 4 or 5 CKD receiving a group II GBCA.

DATA SOURCES

A health sciences informationist searched the Ovid (MEDLINE and MEDLINE Epub Ahead of Print, In-Process & Other Non-Indexed Citation, and Daily and Versions), Embase, Cochrane Central Register of Controlled Trials, Web of Science, and Open Grey databases from inception to January 29, 2019, yielding 2700 citations.

STUDY SELECTION

Citations were screened for inclusion in a multistep process. Agreement for final cohort inclusion was determined by 2 blinded screeners using Cohen κ. Inclusion criteria consisted of stage 4 or 5 CKD with or without dialysis, administration of an unconfounded American College of Radiology classification group II GBCA (gadobenate dimeglumine, gadobutrol, gadoterate meglumine, or gadoteridol), and incident NSF as an outcome. Conference abstracts, retracted manuscripts, narrative reviews, editorials, case reports, and manuscripts not reporting total group II GBCA administrations were excluded.

DATA EXTRACTION AND SYNTHESIS

Data extraction was performed for all studies by a single investigator, including publication details, study design and time frame, patient characteristics, group II GBCA(s) administered, total exposures for patients with stage 4 or stage 5 CKD, total cases of unconfounded NSF, reason for GBCA administration, follow-up duration, loss to follow-up, basis for NSF screening, and diagnosis.

MAIN OUTCOMES AND MEASURES

Pooled incidence of NSF and the associated upper bound of a 2-sided 95% CI (risk estimate) for the pooled data and each of the 4 group II GBCAs.

RESULTS

Sixteen unique studies with 4931 patients were included (κ = 0.68) in this systematic review and meta-analysis. The pooled incidence of NSF was 0 of 4931 (0%; upper bound of 95% CI, 0.07%). The upper bound varied owing to different sample sizes for gadobenate dimeglumine (0 of 3167; upper bound of 95% CI, 0.12%), gadoterate meglumine (0 of 1204; upper bound of 95% CI, 0.31%), gadobutrol (0 of 330; upper bound of 95% CI, 1.11%), and gadoteridol (0 of 230; upper bound of 95% CI, 1.59%).

CONCLUSIONS AND RELEVANCE

This study's findings suggest that the risk of NSF from group II GBCA administration in stage 4 or 5 CKD is likely less than 0.07%. The potential diagnostic harms of withholding group II GBCA for indicated examinations may outweigh the risk of NSF in this population.

TRIAL REGISTRATION

PROSPERO identifier: CRD42019123284.

Optimizing Electronic Release of Imaging Results through an Online Patient Portal

Purpose To determine an optimal embargo period preceding release of radiologic test results to an online patient portal. Materials and Methods This prospective discrete choice conjoint survey with modified orthogonal design was administered to patients by trained interviewers at four outpatient sites and two institutions from December 2016 to February 2018. Three preferences for receiving imaging results associated with a possible or known cancer diagnosis were evaluated: delay in receipt of results (1, 3, or 14 days), method of receipt (online portal, physician's office, or phone), and condition of receipt (before, at the same time as, or after health care provider). Preferences (hereafter, referred to as utilities) were derived from parameter estimates (β) of multinomial regression stratified according to study participant and choice set. Results Among 464 screened participants, the response and completion rates were 90.5% (420 of 464) and 99.5% (418 of 420), respectively. Participants preferred faster receipt of results (P < .001) from their physician (P < .001) over the telephone (P < .001). Each day of delay decreased preference by 13 percentage points. Participants preferred immediate receipt of results through an online portal (utility, -.57) if made to wait more than 6 days to get results in the office and more than 11 days to get results by telephone. Compared with receiving results in their physician's office on day 7 (utility, -.60), participants preferred immediate release through the online portal without physician involvement if followed by a telephone call within 6 days (utility, -0.49) or an office visit within 2 days (utility, -.53). Older participants preferred physician-directed communication (P < .001). Conclusion The optimal embargo period preceding release of results through an online portal depends on the timing of traditional telephone- and office-based styles of communication. © RSNA, 2018 Online supplemental material is available for this article. See also the editorial by Arenson et al in this issue.

Survey Research: A Primer for the Academic Radiologist

Survey research is appealing to many clinical researchers, including radiologists. Emerging interest in patient preferences and patient-centered outcomes related to imaging likely will stimulate additional use of questionnaires in our field. However, like other quantitative methods, survey-based research requires meticulous planning, execution, and analysis to generate reliable results and support meaningful conclusions. The purpose of this review is to provide a guideline for radiologists embarking on this type of research, with attention to questionnaire design, sampling, survey administration, and analysis.