Managing Patients With Unlabeled Passive Implants on MR Systems Operating Below 1.5 T

Journal of Magnetic Resonance Imaging, vol. 59, pp. 1514–1522

Abstract

The standard of care for managing a patient with an implant is to identify the item and to assess the relative safety of scanning the patient. Because the 1.5 T MR system is the most prevalent scanner in the world and 3 T is the highest field strength in widespread use, implants typically have "MR Conditional" (i.e., an item with demonstrated safety in the MR environment within defined conditions) labeling at 1.5 and/or 3 T only. This presents challenges for a facility that has a scanner operating at a field strength below 1.5 T when encountering a patient with an implant, because scanning the patient is considered "off-label." In this case, the supervising physician is responsible for deciding whether to scan the patient based on the risks associated with the implant and the benefit of magnetic resonance imaging (MRI). For a passive implant, the MRI safety-related concerns are static magnetic field interactions (i.e., force and torque) and radiofrequency (RF) field-induced heating. The worldwide utilization of scanners operating below 1.5 T combined with the increasing incidence of patients with implants that need MRI creates circumstances that include patients potentially being subjected to unsafe imaging conditions or being denied access to MRI because physicians often lack the knowledge to perform an assessment of risk vs. benefit. Thus, physicians must have a complete understanding of the MRI-related safety issues that impact passive implants when managing patients with these products on scanners operating below 1.5 T. This monograph provides an overview of the various clinical MR systems operating below 1.5 T and discusses the MRI-related factors that influence safety for passive implants. Suggestions are provided for the management of patients with passive implants labeled MR Conditional at 1.5 and/or 3 T, referred to scanners operating below 1.5 T. The purpose of this information is to empower supervising physicians with the essential knowledge to perform MRI exams confidently and safely in patients with passive implants. LEVEL OF EVIDENCE: 1 TECHNICAL EFFICACY: Stage 3.

Authors 7

1. Frank G. Shellock corresponding

   University of Southern California

   Affiliation as printed

   Keck School of Medicine University of Southern California Los Angeles California USA

   Keck School of Medicine, University of Southern California, Los Angeles, California, USA

2. Matthew Scott Rosen

   Massachusetts General Hospital · Athinoula A. Martinos Center for Biomedical Imaging

   Affiliation as printed

   Department of Radiology A. A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital Boston Massachusetts USA

   Department of Radiology, A. A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Boston, Massachusetts, USA

3. ANDREW G. WEBB Aachen Department of Radiology Leiden University Medical Center Leiden Netherlands Department of Radiology, Leiden University Medical Center

   Leiden University Medical Center

   Affiliation as printed

   Department of Radiology Leiden University Medical Center Leiden Netherlands

   Department of Radiology, Leiden University Medical Center, Leiden, Netherlands

4. William Taylor Kimberly

   Massachusetts General Hospital

   Affiliation as printed

   Division of Neurocritical Care, Department of Neurology Massachusetts General Hospital Boston Massachusetts USA

   Division of Neurocritical Care, Department of Neurology, Massachusetts General Hospital, Boston, Massachusetts, USA

5. Sunder S. Rajan
   Affiliation as printed

   Warrenton Virginia USA

   Warrenton, Virginia, USA

6. Aleksandar N. Nacev
   Affiliation as printed

   Promaxo Oakland California USA

   Promaxo, Oakland, California, USA

7. John V. Crues
   Affiliation as printed

   ProNet Imaging Medical Group and RadNet Management Los Angeles California USA

   ProNet Imaging Medical Group and RadNet Management, Los Angeles, California, USA