MR Labeling and Implant Safety

Amanda Golsch B.S. R.T.(R)(MR)

IRC Magnet Safety

MRI terms used in labeling implants

• The MR imaging community becomes confused by the conditions that are specified in “MR conditional” labeling.

• This confusion can result in potentially harmful MR imaging conditions, or it can prevent subjects/patients from undergoing MR imaging.

IRC Magnet Safety

Previously used terminology

• MR safe: This term indicates that the device, when used in the MR environment, has been demonstrated to present no additional risk to the patient but may affect the quality of the diagnostic information.

• MR compatible: This term indicates that the device, when used in the MR environment, is MR safe and has been demonstrated to neither significantly affect the quality of the diagnostic information nor have its operations affected by the MR device.

http://10.1148/radiol.2531091030

One should avoid…

• Statements that use the terms MR compatible and MR safe without specification of the MR environment in which the device was tested.

• This allows too much interpretation.

One should…

• Use statements such as “intended for use in the MR environment” or similar claims along with appropriate qualifying information.

Updated Terminology

• MR Safe: An item that poses no known hazards in ALL MR imaging environments. MR safe items are nonconducting, nonmetallic, and nonmagnetic items. An example is an item that is made of plastic.

• MR Conditional: An item that has been demonstrated to pose no known hazards in a SPECIFIED MR environment with specified conditions of use.

http://10.1148/radiol.2531091030

Updated terms continued…

• MR Unsafe: An item that is known to pose hazards in ALL MR environments. MR unsafe items include magnetic items such as a pair of ferromagnetic scissors.

http://10.1148/radiol.2531091030

MR Icons

• MR Safe • MR Conditional • MR Unsafe

Images obtained from www.cookmedical.com

Example of MR labeling information for a medical implant or device.

Shellock F G et al. Radiology 2009;253:26-30

©2009 by Radiological Society of North America

What is Angioplasty?

• Angioplasty is a procedure performed by an Interventional Cardiologist.

• It aids in restoring blood flow to the coronary arteries that are blocked or narrowed due to plaque (athrosclerosis).

http://www.nhlbi.nih.gov/health/dci/Diseases/Angioplasty/Angioplasty_WhatIs.html

Stents

• A stent is placed in the artery during angioplasty. The stent is wrapped around a deflated balloon catheter before the catheter is inserted in the artery.

• When the balloon is inflated to compress the plaque, the stent expands and attaches to the artery wall. The stent supports the inner artery wall.

• Some stents are coated with medicines that are slowly and continuously released into the artery. These are called drug-eluting stents. Drug-eluting stents aid in the prevention of restenosis.

http://www.nhlbi.nih.gov/health/dci/Diseases/Angioplasty/Angioplasty_howdone.html

Image of Angioplasty

http://www.nhlbi.nih.gov/health/dci/Diseases/Angioplasty/Angioplasty_howdone.html

Stents continued…

• Multilink Stents: The term multilink refers the the construction of the stent. It is the manner in which the stent is designed.

• There are many manufacturers who make multilink stents.

Multi-Link Zeta by Abbott Vascular

The Multilink Penta by Boston Scientific aka Guidant

Example of what can be found on a stent manufacturer’s website regarding MRFor magnetic field interactions, a static magnetic field strength of 3 tesla with a maximum spatial gradient magnetic field of 3.3 tesla/meter; for MRI-related heating, a maximum whole body averaged specific absorption rate (SAR) of 2.0 W/kg for 15 minutes of MR imaging. While a single stent produced a temperature rise of less than 0.6°C and should not migrate under these conditions, the response of overlapping stents or stents with fractured struts is unknown. Non-clinical testing has not been performed to rule out the possibility of stent migration at field strengths higher than 3 tesla. MR image quality may be compromised if the area of interest is in the exact same area or relatively close to the position of the stent.

http://www.abbottvascular.com/av_dotcom/url/content/en_US/10.10.360.10:10/general_content/Abtdiv_General_Content_0000155.htm

Example of RCA Stenosis and a normal RCA

Pre Angioplasty Post Angioplasty