Coronary Artery Stents: Bare Metal and Drug Eluting

MRI Issues at 3-Tesla and Coronary Artery Stents
Patients with coronary artery disease are often treated by percutaneous transluminal coronary angioplasty (PTCA). Re-narrowing at the angioplasty site, or restenosis, occurs in as many as 50% of patients following PTCA.

Therefore, after coronary artery intervention, either a bare metal or drug eluting stent is placed in an effort to prevent restenosis. There is considerable attention focused on the use of drug eluting stents to prevent coronary artery restenosis that tends to occur in a substantial number of patients following stenting with "bare" devices. Studies have reported that drug eluting stents reduce the incidence of target vessel failure compared to uncoated metallic stents. As such, drug eluting stents are now used on a widespread basis (upwards of 80%) in patients with coronary artery disease.

MRI safety information has been obtained for several bare wire and drug eluting coronary stents, which have been reported to be safe for patients undergoing MR procedures at 3-Tesla or less (i.e., based on assessments of magnetic field interactions and MRI-related heating).

Important Note: In addition to the coronary artery stents shown below, it should be noted that there currently many others that exist and there may be MRI information for these. Therefore, please use The List to find specific MRI information for other coronary artery stents.

Endeavor Drug Eluting Coronary Artery Stent (Medtronic Vascular) - Through non-clinical testing, the Endeavor stent has been shown to be MRI safe at field strengths of 3 Tesla or less, and a maximum whole body averaged specific absorption rate (SAR) of 2.0 W/kg for 15 minutes of MRI. The Endeavor stent should not migrate in this MRI environment. MRI at 3-T or less may be performed immediately following the implantation of the Endeavor stent. Non-clinical testing has not been performed to rule out the possibility of stent migration at field strengths higher than 3-Tesla.

In this testing, the stent produced a maximum temperature rise of 0.5 degrees C at a maximum whole body averaged SAR of 2.0 W/kg for 15 minutes of MRI.

MR imaging quality may be compromised if the area of interest is in the exact same area or relatively close to the position of the stent.

TAXUS Express Paclitaxel-Eluting Coronary Stent (Boston Scientific Corporation) - Through non-clinical testing, the TAXUS Express stent has been shown to be MRI safe at field strengths of 3 Tesla or less, and a maximum whole body averaged specific absorption rate (SAR) of 2.0 W/kg for 15 minutes of MRI. The TAXUS Express stent should not migrate in this MRI environment. MRI at 3-T or less may be performed immediately following the implantation of the TAXUS Express stent. Non-clinical testing has not been performed to rule out the possibility of stent migration at field strengths higher than 3-Tesla.

In this testing, the stent produced a maximum temperature rise of 0.65 degrees C at a maximum whole body averaged SAR of 2.0 W/kg for 15 minutes of MRI. The effect of heating in the MRI environment was similar for overlapping bare metal stents (2 to 5-mm overlap at the ends), made of the same stainless steel material and having the same stent design. The effect of heating in the MRI environment on stents with fractured struts is not known. The temperature rise of 0.65 degrees C for 15 minutes is calculated to result in an increase in cumulative drug release of 0.001% of the total dose.

MR imaging quality may be compromised if the area of interest is in the exact same area or relatively close to the position of the stent.

Liberte Coronary Artery Stent (bare metal coronary artery stent, Boston Scientific Corporation) - The Liberte Stent has been shown to be MR safe at field strengths of 3 Tesla (T) or less, and a maximum whole body averaged specific absorption rate (SAR) of 2.0 W/kg for 15 minutes of MR imaging. The Liberte Stent should not migrate in this MR environment. MR imaging at 3-T or less may be performed immediately following the implantation of the Liberte Stent.

In this testing, the stent experienced a maximum temperature rise of 0.65 degrees C at a maximum whole body averaged SAR of 2 W/kg for 15 minutes of MR imaging. The temperature rise was observed to be similar for comparable bare metal overlapping stents (2 to 5-mm overlap at the ends). Heating has not been determined for fractured struts.

MR imaging quality may be compromised if the area of interest is in the exact same area or relatively close to the position of the stent.

This stent has not been evaluated to determine if it is safe in MRI systems with field strengths greater than 3 T.

TAXUS Liberte Paclitaxel-Eluting Coronary Stent (Boston Scientific Corporation) - Through non-clinical testing, the TAXUS Liberte stent has been shown to be MRI safe at field strengths of 3 Tesla or less, and a maximum whole body averaged specific absorption rate (SAR) of 2.0 W/kg for 15 minutes of MRI. The TAXUS Liberte stent should not migrate in this MRI environment. MRI at 3T or less may be performed immediately following the implantation of the TAXUS Liberte stent. Non-clinical testing has not been performed to rule out the possibility of stent migration at field strengths higher than 3 Tesla.

In this testing, the stent produced a maximum temperature rise of 0.65 degrees C at a maximum whole body averaged SAR of 2.0 W/kg for 15 minutes of MRI. The effect of heating in the MRI environment was similar for overlapping bare metal stents (2 to 5-mm overlap at the ends), made of the same stainless steel material and having the same stent design. The effect of heating in the MRI environment on stents with fractured struts is not known. The temperature rise of 0.65 degrees C for 15 minutes is calculated to result in an increase in cumulative drug release of 0.001% of the total dose.

MR imaging quality may be compromised if the area of interest is in the exact same area or relatively close to the position of the stent.

(Note: "TAXUS" is the trademark name on the drug coating, and refers to the drug eluting coating addition to the bare metal stent. As such, when there is the addition of the drug eluting coating, it will be referred to as the TAXUS and then the specific name of the stent. For example, TAXUS Express stent. The bare metal stent does not contain the TAXUS prefix.)

CYPHER Sirolimus-eluting Coronary Stent (Cordis Corporation/Johnson and Johnson) - Through non-clinical testing, single and two overlapping CYPHER Stents have been shown to be MRI safe at field strengths of 3 Tesla or less, and a maximum whole body averaged specific absorption rate (SAR) of 4.0 W/kg for 15 minutes of MRI. Single and two overlapping CYPHER Stents should not migrate in this MRI environment. Non-clinical testing has not been performed to rule out the possibility of stent migration at field strengths higher than 3-Tesla.

In this testing, single CYPHER Stents up to 33-mm in length produced a temperature rise of less than 1 degree C, and two overlapped 33-mm length CYPHER Stents produced a temperature rise of less than 2 degrees C at a maximum whole body averaged specific absorption rate (SAR) of 4.0 W/kg for 15 minutes of MRI. The effect of heating in the MRI environment for stents with fractured struts is not known. The effect of heating in the MRI environment on the drug or polymer coating is not known.

MR imaging quality may be compromised if the area of interest is in the exact same area or relatively close to the position of the stent.

(Note: This statement applies to all currently marketed CYPHER Stents in the United States.)


MULTI-LINK VISION Coronary Stent
The Guidant MULTI-LINK VISION Coronary Stent has been shown in non-clinical testing to be MRI safe immediately following implantation. MRI test conditions used to evaluate this stent were: for 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.

Contact the respective manufacturer to obtain the latest information for drug eluting stents.