Abbreviations

ACR

American College of Radiology

ASA

American Society of Anesthesiologists

ASTM

American Society for Testing and Materials

MRI

Magnetic resonance imaging

NHMRC

National Health and Medical Research Council

PICO

Patient, interventions, comparators, outcomes

SMRI

Society for Magnetic Resonance Imaging

RCT

randomized controlled trial

Context and Policy Issues

Magnetic resonance imaging (MRI) is a commonly used procedure in the diagnosis and evaluation of diseases. MRI uses a strong magnetic field and radio waves to produce a detailed cross-sectional 3-dimensional image of the patient’s internal organs and structures.¹ While the relative safety and advantages of MRI over other imaging technologies resulted in its ever increasing use, there are a number of safety issues resulting from patient-related and equipment-related factors. Equipment with ferromagnetic property may pose a serious projectile hazard due to magnetic attraction, and should be permanently fixed or tethered to the floor or the wall.² Patients may also suffer from thermal injury resulting from excessive heating of equipment during MRI, particularly with electrical conductive materials.² Electromagnetic interference is another major concern that can cause device malfunction or lead to distortions or artefacts in the MRI image, therefore special protective cables or enclosures are used.²

MRI “safe” equipment is identified as having no ferromagnetic parts or radiofrequency interference.³ MRI “unsafe” equipment is comprised of ferromagnetic materials or those that cause radiofrequency interference.³ MRI “conditional” equipment may contain ferromagnetic parts but can operate properly at a safe distance from the MRI system.³ Equipment with MRI compatibility is necessary to operate in the MRI environment, which conventional accessories are not designed for.³ MRI scanners have magnets with different strengths, and compatibility should always be assessed from reliable sources. In addition, proper labeling of all equipment with specifications to operational conditions is mandatory.¹

The American College of Radiology (ACR) published a guidance document on MR safety practices¹ in which four zones of increasing magnetic sensitivity and barriers to access were described. Zone 1 and 2 constitute the freely accessible area outside the MRI environment and the interface separating the more restricted areas, respectively. Zone III is a restricted area within the MRI suite with strict control on ferromagnetic objects or equipment and should be under supervision of authorized personnel. Zone IV contains the MRI scanner; therefore the highest degree of restriction should be imposed to prevent any magnet-associated hazard.¹

Monitoring of physiological parameters during an MRI examination is necessary for patients who are sedated or anesthetized, critically ill, or have underlying health issues.² The Society for Magnetic Resonance Imaging (SMRI) recommends monitoring of patients at least visually or verbally, and using appropriate physiological monitors for high-risk patients or those unable to respond during MRI.⁵ In addition, some patients may require mechanical ventilation, which require the same safety considerations as monitoring.⁵ A number of guidelines are available to ensure the safety of patients and healthcare professionals working in an MRI unit.^1,4,6–9 However, evidence for clinical effectiveness of equipment used in MRI settings is limited, particularly for ventilators and physiological monitors.

The objective of this report is to summarize the available evidence regarding the clinical effectiveness and evidence-based guidelines for MRI-compatible ventilators and physiological monitoring equipment for use during MRI in adult patients requiring ventilation.

Research Questions

1. What is the clinical effectiveness of magnetic resonance imaging (MRI)-compatible ventilators in adult patients requiring ventilation during an MRI exam?
2. What is the clinical effectiveness of physiological monitoring equipment used during a MRI exam in adult patients on a ventilator?
3. What are the evidence-based guidelines associated with the use of MRI-compatible ventilators for adult patients undergoing a MRI exam?
4. What are the evidence-based guidelines associated with the use of physiological monitoring equipment used for ventilated adult patients during an MRI exam?

Key Findings

No evidence regarding the clinical effectiveness of MRI-compatible ventilators and physiological monitors for ventilated patients during MRI was identified.

No evidence-based guidelines associated with the use of MRI-compatible ventilators and physiological monitoring for ventilated adult patients during MRI exams were found.

Methods

Selection Criteria and Methods

One reviewer screened citations and selected studies. In the first level of screening, titles and abstracts were reviewed and potentially relevant articles were retrieved and assessed for inclusion. The final selection of full-text articles was based on the inclusion criteria presented in Table 1.

Table 1

Selection Criteria.

Summary of Evidence

Conclusions and Implications for Decision or Policy Making

No relevant clinical studies or guidelines were identified from a five-year review of the literature that provided information on the clinical effectiveness, safety and practice guidelines for MRI-compatible ventilators and physiological monitoring among adult patients requiring ventilation during MRI. The paucity in evidence warrants further research in this area. One practice advisory, which did not meet in the inclusion criteria of this review, was primarily targeted towards anesthesiologists to ensure safe practices within an MRI environment and provided information on the safety of physiological monitors.¹⁰ The authors of the advisory indicated that the practice advisory report was not intended as standards or guidelines; instead a set of systematically developed recommendations that may be adopted, modified, or rejected according to the clinical needs and constraints of the local institution. Evidence from several non-comparative observational studies and case reports included in the advisory suggest that monitoring equipment are not associated with serious harms involving the MRI scanner or the individual, other than occasionally evoking a burning sensation or interference with the MRI scan. However, the evidence is not specific to patients on ventilation, and there is significant uncertainty in the quality of the included studies due to a lack of study quality assessment and adequate details. The authors recommended that MRI-compatible ventilators should be available in the unit; however, this appears to be applicable to any equipment used during MRI without any supporting evidence for clinical benefits. The advisory also recommends that anesthesiologists should ensure safety for all personnel within the MRI location, and responsible for inspecting and labeling all equipment for MRI compatibility, communicating with other healthcare professionals in case patients require ventilation, monitoring or other steps, providing anesthetic care, and management of any emergencies. With no recently published comparative data or guidelines on the safety and clinical effectiveness of MRI-compatible ventilators and physiological monitors for ventilated patients, there is a significant dearth in the evidence to inform policy decisions.

References

1.

Expert Panel on MR Safety, Kanal E, Barkovich J, Bell C, Borgstede JP, Bradley WG Jr., et al. ACR guidance document on MR safe practices: 2013. J Magn Reson Imaging. 2013;37:501–530. 10.1002/jmri.24011 Accessed 2018 Jun 19. [PubMed: 23345200] [CrossRef]

2.

Shellock FG. Monitoring patients in the MR environment. MRISafety.com. Shellock R and D Services; 2018. http://www​.mrisafety.com Accessed 2018 Jun 19.

3.

ASTM International. ASTM F2503-05: Standard practice for marking medical devices and other items for safety in the magnetic resonance environment. West Conshohocken (PA): ASTM International; 2013 https://www​.astm.org/Standards/F2503.htm Accessed 2018 Jun 19. [PubMed: 30033971]

4.

Healthcare Human Factors Group. Magnetic resonance imaging environment safety in Ontario. Toronto (ON): University Health Network; 2006 Apr. http://www​.ontla.on.ca​/library/repository/mon/14000/264026​.pdf Accessed 2018 Jun 19.

5.

Shellock FG KE. Policies, guidelines, and recommendations for MR imaging safety and patient management. SMRI Safety Committee. J Magn Reson Imaging. 1991 Jan-Feb;1(1):97–101. https://www​.ncbi.nlm​.nih.gov/pubmed/1802138 Accessed 2018 Jun 19. [PubMed: 1802138]

6.

Chakraborty S, Johnson MA, Miller W, Noseworthy MD, Seely J, Dennie C, et al. CAR Standard for magnetic resonance imaging. Ottawa (ON): Canadian Association of Radiologists (CAR); 2011 Apr. https://car​.ca/wp-content​/uploads/Magnetic-Resonance-Imaging-2011.pdf Accessed 2018 Jun 19.

7.

MHRA. Safety guidelines for magnetic resonance imaging equipment in clinical use. London, England: Medicines and Healthcare Products Regulatory Agency (MHRA); 2015 Mar. https://assets​.publishing​.service.gov.uk​/government/uploads/system​/uploads/attachment_data​/file/476931​/MRI_guidance_2015_-_4-02d1.pdf Accessed 2018 Jun 19.

8.

Health Quality Ontario. Patient monitoring system for MRI: an evidence-based analysis. Ont Health Technol Assess Ser. 2003; 3(7): 1–16. https://www​.ncbi.nlm​.nih.gov/pmc/articles/PMC3387746/ Accessed 2018 Jun 19. [PMC free article: PMC3387746] [PubMed: 23074447]

9.

The Ontario Health Technology Advisory Committee (OHTAC) Report of the diagnostic imaging safety committee for magnetic resonance imaging (MRI). Toronto (ON): OHTAC; 2007 Feb. http://www​.health.gov​.on.ca/en/common/ministry​/publications/reports​/disc_ct_mri/mri_report.pdf Accessed 2018 Jun 19.

10.

Practice advisory on anesthetic care for magnetic resonance imaging: an updated report by the American Society of Anesthesiologists Task Force on Anesthetic Care for Magnetic Resonance Imaging. Anesthesiol. 2015;122(3):495–520. [PubMed: 25383571]

Appendix 1. Selection of Included Studies

Appendix 1. Additional References of Potential Interest

Version: 1.0

Suggested citation:

MRI-compatible ventilators and physiological equipment for patients undergoing MRI exams: a review of clinical effectiveness and guidelines. Ottawa: CADTH; 2018 Jun. (CADTH rapid response report: summary with critical appraisal).

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