Cook Medical adheres to the F2503-08 standard of MR (magnetic resonance) terminology adopted by the American Society for Testing and Materials (ASTM). This practice of marking medical devices came about in an effort to clarify the terminology, provide a uniform system for marking and, more important, because misuse of old terminology could result in serious injuries for patients and other individuals. This new system references the MR environment where testing took place, which includes field strength, spatial gradients, dB/dt (time rate of change of the magnetic field), radio frequency (RF) fields and specific absorption rate (SAR).

Taking these conditions into consideration, three new categories of MR marking exist: 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 MR 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 MR 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 MR 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 MR 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, may be required.
	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.

Read Zenith Endovascular Graft Frequently Asked Questions

MRI Information
Non-clinical testing has demonstrated that the Zenith AAA Endovascular Graft is MR Conditional. A patient with this endovascular graft can be scanned safely immediately after placement under the following conditions:

Static Magnetic Field

• Static magnetic field of 3.0 Tesla or less.
• Highest spatial magnetic gradient field of 720 gauss/cm

Non-clinical evaluation was conducted in a 3 Tesla MR system (General Electric Excite) with a maximum spatial magnetic gradient field of 720 gauss/cm as measured with a gaussmeter in the position of the static magnetic field pertinent to the patient (i.e., outside of scanner covering, accessible to a patient or individual).

MRI-Related Heating

1.5 Tesla Systems:

• Static magnetic field of 1.5 Tesla
• Maximum whole-body-averaged specific absorption rate (SAR) of 2 W/kg for 15 minutes of scanning (i.e., per scanning sequence)

In non-clinical testing, the Zenith AAA Endovascular Graft produced a temperature rise of less than or equal to 1.4°C at a MR system reported whole-body-averaged specific absorption rate (SAR) of 2.8 W/kg for 15 minutes of MR scanning in a 1.5 Tesla Magnetom, Siemens Medical Magnetom, Numaris/4 Software, Version Syngo MR 2002B DHHS MR Scanner. The maximum whole-body-averaged specific absorption rate (SAR) was 2.8 W/kg, which corresponds to a calorimetry measured value of 1.5 W/kg.

3.0 Tesla Systems:

• Static magnetic field of 3.0 Tesla
• Maximum whole-body-averaged specific absorption rate (SAR) of 2 W/kg for 15 minutes of scanning (i.e., per scanning sequence)

In non-clinical testing, the Zenith AAA Endovascular Graft produced a temperature rise of less than or equal to 1.9°C at a MR system reported whole-body-averaged specific absorption rate (SAR) of 3.0 W/kg for 15 minutes of MR scanning in a 3.0 Tesla Excite, GE Electric Healthcare, G3.0-052B Software, MR Scanner. The maximum whole-body-averaged specific absorption rate (SAR) was 3.0 W/kg, which corresponds to a calorimetry measured value of 2.8 W/kg.

Image Artifact

The image artifact extends throughout the anatomical region containing the device, obscuring the view of immediately adjacent anatomical structures within approximately 20 cm of the device, as well as the entire device and its lumen, when scanned in nonclinical testing using the sequence: Fast spin echo, in a 3.0 Tesla, Excite, GE Electric Healthcare, with G3.0-052B Software, MR system with body radiofrequency coil.

For all scanners, the image artifact dissipates as the distance from the device to the area of interest increases. MR scans of the head and neck and lower extremities may be obtained without image artifact. Image artifact may be present in scans of the abdominal region and upper extremities, depending on distance from the device to the area of interest.

Clinical information is available for seventeen patients who received MRI scans after stent-graft implantation. There have been no reported adverse events or device problems in any of these patients as a result of having received an MRI. Additionally, there have been well over 100,000 Zenith AAA Endovascular Grafts implanted worldwide, in which there have been no reported adverse events or device problems as a result of MRI.

Cook recommends that the patient register the MR conditions disclosed in this IFU with the MedicAlert Foundation. The MedicAlert Foundation can be contacted in the following manners:

The MRI Information of the Zenith Renu® AAA Ancillary Graft is based upon MRI Information of the Zenith® AAA Endovascular Graft, which is made from stents of the same metal.

MRI Information
Non-clinical testing has demonstrated that the Zenith AAA Endovascular Graft is MR Conditional. A patient with this endovascular graft can be scanned safely immediately after placement under the following conditions:

Static Magnetic Field

• Static magnetic field of 3.0 Tesla or less.
• Highest spatial magnetic gradient field of 720 gauss/cm

Non-clinical evaluation was conducted in a 3 Tesla MR system (General Electric Excite) with a maximum spatial magnetic gradient field of 720 gauss/cm as measured with a gaussmeter in the position of the static magnetic field pertinent to the patient (i.e., outside of scanner covering, accessible to a patient or individual).

MRI-Related Heating

1.5 Tesla Systems:

• Static magnetic field of 1.5 Tesla
• Maximum whole-body-averaged specific absorption rate (SAR) of 2 W/kg for 15 minutes of scanning (i.e., per scanning sequence)

In non-clinical testing, the Zenith AAA Endovascular Graft produced a temperature rise of less than or equal to 1.4°C at a MR system reported whole-body-averaged specific absorption rate (SAR) of 2.8 W/kg for 15 minutes of MR scanning in a 1.5 Tesla Magnetom, Siemens Medical Magnetom, Numaris/4 Software, Version Syngo MR 2002B DHHS MR Scanner. The maximum whole-body-averaged specific absorption rate (SAR) was 2.8 W/kg, which corresponds to a calorimetry measured value of 1.5 W/kg.

3.0 Tesla Systems:

• Static magnetic field of 3.0 Tesla
• Maximum whole-body-averaged specific absorption rate (SAR) of 2 W/kg for 15 minutes of scanning (i.e., per scanning sequence)

In non-clinical testing, the Zenith AAA Endovascular Graft produced a temperature rise of less than or equal to 1.9°C at a MR system reported whole-body-averaged specific absorption rate (SAR) of 3.0 W/kg for 15 minutes of MR scanning in a 3.0 Tesla Excite, GE Electric Healthcare, G3.0-052B Software, MR Scanner. The maximum whole-body-averaged specific absorption rate (SAR) was 3.0 W/kg, which corresponds to a calorimetry measured value of 2.8 W/kg.

Image Artifact

The image artifact extends throughout the anatomical region containing the device, obscuring the view of immediately adjacent anatomical structures within approximately 20 cm of the device, as well as the entire device and its lumen, when scanned in non-clinical testing using the sequence: Fast spin echo, in a 3.0 Tesla, Excite, GE Electric Healthcare, with G3.0-052B Software, MR system with body radiofrequency coil.

For all scanners, the image artifact dissipates as the distance from the device to the area of interest increases. MR scans of the head and neck and lower extremities may be obtained without image artifact. Image artifact may be present in scans of the abdominal region and upper extremities, depending on distance from the device to the area of interest.

Clinical information is available for seventeen patients who received MRI scans after stent-graft implantation. There have been no reported adverse events or device problems in any of these patients as a result of having received an MRI. Additionally, there have been well over 100,000 Zenith AAA Endovascular Grafts implanted worldwide, in which there have been no reported adverse events or device problems as a result of MRI.

Cook recommends that the patient register the MR conditions disclosed in this IFU with the MedicAlert Foundation. The MedicAlert Foundation can be contacted in the following manners:

MRI Information
Non-clinical testing has demonstrated that the Zenith Spiral-Z AAA Iliac Leg Graft is MR Conditional. A patient with this endovascular graft can be scanned safely immediately after placement under the following conditions:

Static Magnetic Field

• Static magnetic field of 3.0 Tesla or less.
• Highest spatial magnetic gradient field of 720 Gauss/cm

Non-clinical evaluation was conducted in a 3 Tesla MR system (General Electric Excite) with a maximum spatial magnetic gradient field of 720 Gauss/cm as measured with a gaussmeter in the position of the static magnetic field pertinent to the patient (i.e., outside of scanner covering, accessible to a patient or individual).

MRI-Related Heating

1.5 Tesla Systems:

• Static magnetic field of 1.5 Tesla
• Maximum whole-body-averaged specific absorption rate (SAR) of 2 W/kg for 15 minutes of scanning (i.e., per scanning sequence)

In non-clinical testing, the Zenith Spiral-Z AAA Iliac Leg produced a temperature rise of less than or equal to 2.1 °C at a MR system reported whole-body-averaged specific absorption rate (SAR) of 2.9 W/kg, for 15 minutes of MR scanning in a 1.5 Tesla Magnetom, Siemens Medical Magnetom, Numaris/4 Software, Version Syngo MR 2002B DHHS MR Scanner. The maximum whole-body-averaged specific absorption rate (SAR) was 2.9 W/kg, which corresponds to a calorimetry measured value of 2.1 W/kg.

3.0 Tesla Systems:

• Static magnetic field of 3.0 Tesla
• Maximum whole-body-averaged specific absorption rate (SAR) of 2 W/kg for 15 minutes of scanning (i.e., per scanning sequence)

In non-clinical testing, the Zenith Spiral-Z AAA Iliac Leg produced a temperature rise of less than or equal to 2.6 °C at a MR system reported whole-body-averaged specific absorption rate (SAR) of 2.9 W/kg, for 15 minutes of MR scanning in a 3.0 Tesla Excite, GE Electric Healthcare, 14X. M5 Software, MR Scanner. The maximum whole-body-averaged specific absorption rate (SAR) was 2.9 W/kg, which corresponds to a calorimetry measured value of 2.7 W/kg.

Image Artifact

The image artifact extends throughout the anatomical region containing the device, obscuring the view of immediately adjacent anatomical structures within approximately 5 cm of the device, as well as the entire device and its lumen, when scanned in nonclinical testing using the sequence: Fast spin echo, in a 3.0 Tesla, Excite, GE Electric Healthcare, with G3.0-052B Software, MR system with body radiofrequency coil.

For all scanners, the image artifact dissipates as the distance from the device to the area of interest increases. MR scans of the head and neck and lower extremities may be obtained without image artifact. Image artifact may be present in scans of the abdominal region, depending on distance from the device to the area of interest.

Clinical information is available for seventeen patients who received MRI scans after stent-graft implantation. There have been no reported adverse events or device problems in any of these patients as a result of having received an MRI. Additionally, there have been well over 100,000 Zenith AAA Endovascular Grafts implanted worldwide, in which there have been no reported adverse events or device problems as a result of MRI.

Cook recommends that the patient register the MR conditions disclosed in this IFU with the MedicAlert Foundation. The MedicAlert Foundation can be contacted in the following manners:

MRI Information
Non-clinical testing has demonstrated that the Zenith TX2 TAA Endovascular Graft with Pro-Form is MR Conditional. It can be scanned safely under the following conditions:

1.5 Tesla Systems:

• Static magnetic field of 1.5 Tesla
• Spatial gradient field of 450 Gauss/cm
• Maximum whole-body-averaged specific absorption rate (SAR) of 2 W/kg for 15 minutes of scanning.

In non-clinical testing, the Zenith TX2 TAA Endovascular Graft with Pro-Form produced a temperature rise of less than 1.4 °C at a maximum whole-body-averaged specific absorption rate (SAR) of 2.8 W/kg for 15 minutes of MR scanning in a 1.5 Tesla Magnetom, Siemens Medical Magnetom MR scanner. The maximum whole-body-averaged specific absorption rate (SAR) was 2.8 W/kg, which corresponds to a calorimetry measured value of 1.5 W/kg.

3.0 Tesla Systems:

• Static magnetic field of 3.0 Tesla
• Spatial gradient field of 720 Gauss/cm
• Maximum whole-body-averaged specific absorption rate (SAR) of 2 W/kg for 15 minutes of scanning

In non-clinical testing, the Zenith TX2 TAA Endovascular Graft with Pro-Form produced a temperature rise of less than 1.9 °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, Excite, GE Electric Healthcare MR scanner. The maximum whole-body-averaged specific absorption rate (SAR) was 3.0 W/kg, which corresponds to a calorimetry measured value of 2.8 W/kg.

The image artifact extends throughout the anatomical region containing the device, obscuring the view of immediately adjacent anatomical structures within approximately 20 cm of the device, as well as the entire device and its lumen, when scanned in non-clinical testing using the sequence: Fast spin echo in a 3.0 Tesla, Excite, GE Electric Healthcare, with G3.0-052B software, MR system with body radiofrequency coil.

For all scanners, the image artifact dissipates as the distance from the device to the area of interest increases. MR scans of the lower extremities may be obtained without image artifact. Image artifact may be present in scans of the abdominal, upper extremity, and head and neck region, depending on distance from the device to the area of interest.

Clinical information is available on six patients who received MRI scans during the course of the clinical trial. There have been no reported adverse events or device problems in any of these patients as a result of having received an MRI. Additionally, there have been approximately 3,000 patients implanted with Zenith TAA Endovascular Grafts worldwide, in which there have been no reported adverse events or device problems as a result of MRI.

Cook recommends that the patient register the MR conditions disclosed in this IFU with the MedicAlert Foundation. The MedicAlert Foundation can be contacted in the following manners:

The following is a list of frequently asked questions and answers regarding Cook Medical's MR marking statement for Zenith® endovascular grafts.

1. Which Zenith devices are covered in this statement?
All Zenith grafts that have been or currently are commercially available in the U.S. are covered by the new Zenith MR Conditional statement, including:

• Zenith AAA Endovascular Grafts (main body and iliac legs)
• Zenith Flex® AAA Endovascular Grafts (main body, iliac legs and main body extensions)
• Zenith AAA Endovascular Graft Ancillary Components (main body extensions, iliac leg extensions, converters, occluders and iliac plugs)
• Zenith Renu® AAA Ancillary Grafts (main body extension and converter configurations). Refer to question #16.
• Zenith TX2® TAA Endovascular Grafts (proximal components, proximal tapered components, distal components, proximal extensions and distal extensions)

2. Is the new Zenith MR Conditional statement retroactive and applicable to all Zenith products?
The new Zenith MR Conditional statement covers all Zenith grafts that have been or currently are commercially available in the U.S. See the answer to question #1 for a complete list of Zenith products.

3. Is there a limit to how many components of the Zenith graft can be in a patient undergoing an MRI procedure (e.g., multiple iliac leg extensions, main body extensions, etc.)?
No limit to the number of components that can be scanned has been established.

4. The patient's current Zenith patient ID card says the patient should not undergo an MRI procedure. Do we follow the card or follow the current website information?
You should follow the current website information. The information shown on the website reflects updated testing and information for Zenith devices and replaces the information that was current at the time that the patient's device and device ID card were produced.

5. On the patient ID card is the statement, “Because of potential risks, the MRI facility should allow for prompt intervention, if necessary.” Does Cook advise free-standing MRI centers not scan this patient, as they are not prepared for prompt intervention?
As long as the MR Conditional parameters are followed, patients with Zenith grafts may be safely scanned.

6. Can patients with a Zenith graft safely undergo an MRI procedure?
The Zenith grafts are considered MR conditional according to the terms specified in the American Society for Testing and Materials (ASTM) International, Designation: F2503-08, Standard Practice for Marking Medical Devices and Other Items for Safety in the Magnetic Resonance Environment. MR Conditional means the Zenith graft products have been demonstrated to pose no known hazards in a specified MR environment with specified conditions of use. The specified MR environment and specified conditions of use for the Zenith grafts are listed in the Zenith MR Conditional statement that can be found at http://www.cookmedical.com/ai/productMri.do.

7. What changed in the Zenith graft so that it is now labeled as “MR Conditional”?
Nothing has changed with the Zenith graft. Additional MR testing and analyses were performed that confirm the grafts fall within the FDA guidelines of the term MR Conditional.

8. Under what conditions were the grafts tested?
The test conditions associated with MR testing are stated in the Instructions for Use. These Instructions for Use can be found on the Cook Medical website at https://ifu.cookmedical.com/ifuPub/searchIfu.jsf.

9. When may a patient with a Zenith graft safely undergo an MRI procedure?
A patient with a Zenith graft may be scanned safely anytime after placement under the conditions stated in the Instructions for Use.

10. What is the specific absorption rate (SAR)?
Specific absorption rate, or SAR, is a measure of the absorption of radio frequency energy deposited in biological tissue. SAR is typically measured in watts per kilogram (W/kg).The SAR value is estimated by the MR system, based on the patient's body weight and imaging parameters selected for the MRI examination.

11. May a patient with a Zenith endovascular graft undergo MR imaging for more than 15 minutes?
In the labeling of the Zenith products, the maximum whole-body-averaged SAR is reported as a function of watts per kilogram over a continuous 15 minute period of scanning, per pulse sequence (i.e., not for the entire MRI examination). A patient may undergo multiple scan sequences where no single pulse sequence is longer than 15 minutes.

12. Do the stainless steel stents of the Zenith devices produce unsafe levels of magnetic field interactions during exposure to the MR system? 
The magnetic field interactions associated with the Zenith products have been established to be acceptable for patients under the MR conditions (3 tesla or less; highest spatial gradient of 720 gauss/cm) and based on non-clinical testing as well as clinical data.

13. What does the highest spatial magnetic field gradient of 720 gauss/cm mean? How is this identified for a specific MR system?
The spatial magnetic field gradient is defined as the rate of change in the magnetic field as a function of position. Nonclinical evaluation was conducted in a 3 tesla MR system with a maximum spatial magnetic field gradient of 720 gauss/cm as measured with a gaussmeter in the position of the static magnetic field pertinent to the patient (i.e., outside of scanner covering, accessible to a patient or individual). The maximum spatial magnetic field gradient reported by the MR system manufacturer is often within the scanner covering (i.e., not accessible to the patient), thus it is important to accurately determine the maximum spatial magnetic field gradient of a particular MR system.

14. What is the maximum whole-body-averaged SAR reported by the MR system?
This SAR value as reported by the MR system is an estimation of the RF power deposition in the patient based on the body weight of the patient and the imaging parameters selected for use in the MRI procedure.

15. What is the maximum whole-body-averaged SAR as measured by calorimetry?
This is the actual, measured SAR of the gelled saline phantom used in non-clinical testing to assess MRI-related heating.

16. Is it acceptable to perform an MRI examination in a patient with a Zenith Renu AAA Ancillary Graft used in conjunction with a preexisting graft?
If the preexisting graft is “MR Unsafe,” the MRI should not be performed. If the preexisting graft is “MR Safe” or “MR Conditional,” the MRI can be performed under the conditions stated in the Zenith MRI labeling statement and by the manufacturer of the preexisting graft, with the following exception: The feasibility of scanning the Zenith Renu AAA Ancillary Graft inside a preexisting graft that contains metallic stents on the inner diameter of the graft for a significant length (> 50 mm) has not been established and may pose a risk associated with MRI-related heating.