Cook Medical adheres to the system of MRI terminology developed in 2005 by the American Society for Testing and Materials (ASTM). This adoption came about in an effort to clarify the terminology and, more important, because misuse of old terminology could result in serious accidents for patients and other individuals. This new system references the MRI environment where testing took place, which includes the location inside the static magnetic field and its magnitude, spatial gradients, time-varying magnetic fields, radio frequency (RF) magnetic field pulses and specific absorption rates (SAR).

Taking these conditions into consideration, three new categories were developed: MR Safe, MR Conditional, and MR Unsafe. In this system, "safe" and "unsafe" are the two extremes. "Conditional" is in the middle and characterizes the behavior of a medical device under specific conditions in the MRI environment as determined by testing. In addition to the new terms, the ASTM International document introduced corresponding icons consistent with international standards for colors and shapes of safety signs. The icons are intended for use on items that may be brought into or near the MRI environment as well as in product labeling. The new terminology and icon structure is intended to help clarify matters related to biomedical implants and devices to ensure the safe use of MRI technology.

	MR Safe—An item that poses no known hazards in all MRI environments. MR Safe items include nonconducting, nonmetallic, nonmagnetic items such as plastic, silicone and glass. An item may be determined to be MR Safe on the basis of scientific rationale rather than test data.
	MR Conditional—An item that has been demonstrated to pose no known hazards in a specified MRI environment with specified conditions of use. Field conditions should be enumerated on the product, its packaging or in the enclosed literature. Additional conditions, including specific configurations of the item (e.g., the routing of leads used for a neurostimulation system) may be required.
	MR Unsafe—An item that is known to pose hazards in all MRI environments. MR Unsafe items include magnetic items such as a pair of ferromagnetic scissors.

Conichrome is a trademark of Carpenter Technologies.
Inconel is a registered trademark of Huntington Alloys Corporation.

Nonclinical testing has demonstrated that the Cook Celect Vena Cava Filter is MR Conditional. It can be scanned safely immediately after placement under the following conditions:

• Static magnetic field strengths of 3.0 tesla or less
• Maximum spatial gradient field of 330 gauss/cm or less
• Maximum whole-body averaged specific absorption rate (SAR) of 2.0 W/kg for 15 minutes of scanning

In nonclinical testing, the Cook Celect Vena Cava Filter produced a temperature rise of less than 0.2°C at a maximum whole-body averaged specific absorption rate (SAR) of 2.0 W/kg for 15 minutes of MR scanning in a 3.0 tesla MR system using a transmit/receive body coil MR scanner. MR image quality may be compromised if the area of interest is in the same area or relatively close to the position of the Cook Celect Vena Cava Filter. Therefore, it may be necessary to optimize MR imaging parameters for the presence of this metallic implant.

Stainless steel coils are ferrous and are affected by the MR field. Benchtop testing on stainless steel embolization coil samples showed high degrees of torque and deflection. Therefore, stainless steel embolization coils have a designation of MR Unsafe and we would not recommend scanning a patient implanted with a stainless steel embolization coil.

Nonclinical testing has demonstrated that the Formula biliary stent is MR Conditional. A patient with this stent may undergo MRI immediately after placement under the following conditions:

• Static magnetic field of 3.0 tesla or less
• Maximum spatial gradient magnetic field of 720 gauss/cm
• Maximum MR system reported whole-body averaged specific absorption rate (SAR) of 3.0 W/kg for 15 minutes of scanning

In nonclinical testing, the Formula biliary stent produced a temperature rise of less than 1°C at an MR-system-reported maximum whole-body averaged specific absorption rate (SAR) of 3 W/kg for 15 minutes of MR scanning in a 3 tesla system (Excite, Software G3.0-052B, GE Healthcare).

MR image quality may be compromised if the area of interest is in the same area or relatively close to the position of the Formula biliary stent. Therefore, it may be necessary to optimize MR imaging parameters for the presence of this metallic implant. The effect of heating in the MRI environment for overlapping stents or stents with fractured struts is unknown.

Nonclinical testing has demonstrated that the Günther Tulip Vena Cava Filter is MR Conditional. It can be scanned safely immediately after placement under the following conditions:

• Static magnetic field strengths of 3.0 tesla or less
• Maximum spatial gradient field of 525 gauss/cm or less
• Maximum whole-body averaged specific absorption rate (SAR) of 3.0 W/kg for 15 minutes of scanning

In nonclinical testing, the Günther Tulip Vena Cava Filter produced a temperature rise of less than 0.6°C at a maximum whole-body averaged specific absorption rate (SAR) of 3.0 W/kg for 15 minutes of MR scanning in a 3.0 tesla MR system using a transmit/receive body coil (Excite, Software G3.0-052B, GE Healthcare, Milwaukee, WI).

MR image quality may be compromised if the area of interest is in the same area or relatively close to the position of the Günther Tulip Vena Cava Filter. Therefore, it may be necessary to optimize MR imaging parameters for the presence of this metallic implant.

Nonclinical testing has demonstrated that the Gianturco-Roehm Bird's Nest Vena Cava Filter is MR Conditional. According to the article “MR Imaging of the Bird's Nest Filter” by Alyssa T. Watanabe, “No complication or symptomatic filter displacement was encountered as a result of MR imaging performed at 1.5 T.” The article also states that the filters created significant local artifact distortion on MR images; however, diagnostic images of the pelvis, spine and brain may still be obtained.

MRI diagnostic procedures should be postponed for six weeks following filter implantation to ensure device incorporation into the vessel wall.

Hilal Embolization Microcoils are manufactured from a platinum composition that has been shown to have no ferromagnetic response. Through nonclinical testing, embolization coils manufactured of this material have been shown to be MR Conditional. A patient with one of these implants can be safely scanned immediately after placement under the following conditions:

• Static magnetic field strengths of 3.0 tesla or less
• Maximum spatial gradient field of 330 gauss/cm
• Maximum MR system whole-body averaged specific absorption rate (SAR) of 3 W/kg for 15 minutes of scanning

In this testing, platinum embolization coils produced a temperature rise of greater than 0.5°C at a maximum whole-body averaged specific absorption rate (SAR) of 2.0 W/kg for 20 minutes of MRI. The effect of heating for other conditions, multiple coils or overlapping coils is unknown.

MR image quality may be compromised if the area of interest is in the same area or relatively close to the position of platinum embolization coils.

Through nonclinical testing, the MReye Embolization Coil has been shown to be MR Conditional. It can be scanned safely immediately after placement under the following conditions:

• Static magnetic field strengths of 3.0 tesla or less
• Maximum spatial gradient of 330 gauss/cm
• Maximum whole-body averaged specific absorption rate (SAR) of 2.0 W/kg for 20 minutes of MRI

The MReye Embolization Coil will not migrate in this MRI environment. Nonclinical testing has not been performed to rule out the possibility of device migration at static magnetic field strengths higher than 3.0 tesla and a maximum spatial gradient higher than 330 gauss/cm.

In this testing, the MReye Embolization Coil produced a temperature rise of greater than or equal to 0.6°C at a maximum whole-body averaged specific absorption rate (SAR) of 2.0 W/kg for 20 minutes of MRI. The effect of heating in the MRI environment for other conditions, multiple coils or overlapping coils is unknown.

MRI image quality may be compromised if the area of interest is in the exact same area or relatively close to the position of the MReye Embolization Coil.

Through nonclinical testing, the MReye Flipper Detachable Embolization Coil Delivery System has been shown to be MR Conditional. It can be scanned safely immediately after placement under the following conditions:

• Static magnetic field strengths of 3.0 tesla or less
• Maximum spatial gradient of 330 gauss/cm
• Maximum whole-body averaged specific absorption rate (SAR) of 2.0 W/kg for 20 minutes of MRI

Embolization coils manufactured of Inconel will not migrate in this MRI environment. Nonclinical testing has not been performed to rule out the possibility of device migration at static magnetic field strengths higher than 3.0 tesla and a maximum spatial gradient higher than 330 gauss/cm.

In this testing, the MReye Flipper Embolization Coil produced a temperature rise of greater than or equal to 0.6°C at a maximum whole-body averaged specific absorption rate (SAR) of 2.0 W/kg for 20 minutes of MRI. The effect of heating in the MRI environment for other conditions, multiple coils or overlapping coils is unknown.

MRI image quality may be compromised if the area of interest is in the same area or relatively close to the position of the MReye Flipper Embolization Coil.

Nester Embolization Coils are manufactured from a platinum composition that has been shown to have no ferromagnetic response. Through nonclinical testing, embolization coils manufactured of this material have been shown to be MR Conditional. A patient with one of these implants can be scanned safely immediately after placement under the following conditions:

• Static magnetic field strengths of 3.0 tesla or less
• Maximum spatial gradient field of 330 gauss/cm
• Maximum MR system whole-body averaged specific absorption rate (SAR) of 3 W/kg for 15 minutes of scanning

In this testing, platinum embolization coils produced a temperature rise of greater than 0.5°C at a maximum whole-body averaged specific absorption rate (SAR) of 2.0 W/kg for 20 minutes of MRI. The effect of heating for other conditions, multiple coils or overlapping coils is unknown.

MR image quality may be compromised if the area of interest is in the same area or relatively close to the position of platinum embolization coils.

Tornado Embolization Coils are manufactured from a platinum composition that has been shown to have no ferromagnetic response. Through nonclinical testing, embolization coils manufactured of this material have been shown to be MR Conditional. A patient with one of these implants can be scanned safely immediately after placement under the following conditions:

• Static magnetic field strengths of 3.0 tesla or less
• Maximum spatial gradient field of 330 gauss/cm
• Maximum MR system whole-body averaged specific absorption rate (SAR) of 3 W/kg for 15 minutes of scanning

In this testing, platinum embolization coils produced a temperature rise of greater than 0.5°C at a maximum whole-body averaged specific absorption rate (SAR) of 2.0 W/kg for 20 minutes of MRI. The effect of heating for other conditions, multiple coils or overlapping coils is unknown.

MR image quality may be compromised if the area of interest is in the same area or relatively close to the position of platinum embolization coils.

Nonclinical testing has demonstrated that the Zilver Self-Expanding Stent is MR Conditional. It can be scanned safely under the following conditions:

• Static magnetic field of 3 tesla or less
• Spatial gradient field of 720 gauss/cm or less
• Whole-body averaged specific absorption rate (SAR) of 1.5 W/kg (for a single stent at 1.5 tesla) and 3 W/kg (for a single stent at 3 tesla and a pair of overlapping stents at 1.5 and 3 tesla) for 20 minutes (for a single stent at 1.5 tesla) and 15 minutes of scanning (for a single stent at 3 tesla and a pair of overlapping stents at 1.5 and 3 tesla), respectively.

In nonclinical testing, the Zilver Self-Expanding Stent produced maximum temperature rises of 0.1, 3.8, 0.8, and 0.1 degrees C (for a single stent at 1.5 tesla, a pair of overlapping stents at 1.5 tesla, a single stent at 3 tesla, and a pair of overlapping stents at 3 tesla, respectively) at whole-body averaged specific absorption rates (SAR) of 1.5 W/kg (for a single stent at 1.5 tesla) and 3 W/kg (for a single stent at 3 tesla and a pair of overlapping stents at 1.5 and 3 tesla) for 20 minutes (for a single stent at 1.5 tesla) and 15 minutes (for a single stent at 3 tesla and a pair of overlapping stents at 1.5 and 3 tesla) of MR scanning in a 1.5 tesla/64 MHz GE Healthcare MR scanner, a 1.5 tesla Magnetom Siemens Medical Solutions MR Scanner (to evaluate a pair of overlapping stents), and a 3 tesla Excite GE Healthcare MR scanner.

MR image quality may be compromised if the area of interest is in the same area or relatively close to the position of the Zilver Self-Expanding Stent. Therefore, it may be necessary to optimize MR imaging parameters for the presence of this metallic implant.

Heating in the MRI environment for stents with fractured struts is not known.