Subject: On-X Prosthetic Heart Valve MRI Information
Date: March 2010
MR Conditional 
The On-X Prosthetic Heart Valve, Conform-X Mitral Heart Valve Prosthesis; Size 25-33* was determined to be MR-conditional according to the terminology 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. ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, Pennsylvania.
Non-clinical testing demonstrated that the On-X Conform-X Mitral Heart Valve Prosthesis; Size 25-33 is MR Conditional. A patient with this device can be scanned safely immediately after placement under the following conditions:
Static Magnetic Field
-Static magnetic field of 3-Tesla or less
-Maximum spatial gradient magnetic field of 720-Gauss/cm or less
MRI-Related Heating
In non-clinical testing, the On-X Prosthetic Heart Valve, Conform-X Mitral Heart Valve Prosthesis; Size 25-33 produced the following temperature rise during MRI performed for 15-min of scanning (i.e., per pulse sequence) in the 3-Tesla (3-Tesla/128-MHz, Excite, HDx, Software 14X.M5, General Electric Healthcare, Milwaukee, WI) MR system:
Highest temperature change +1.6°C
Therefore, the MRI-related heating experiments for the On-X Conform-X Mitral Heart Valve Prosthesis; Size 25-33 at 3-Tesla using a transmit/receive RF body coil at an MR system reported whole body averaged SAR of 2.9 -W/kg (i.e., associated with a calorimetry measured whole body averaged value of 2.7-W/kg) indicated that the greatest amount of heating that occurred in association with these specific conditions was equal to or less than +1.6°C.
Artifact Information
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 On-X Conform-X Mitral Heart Valve Prosthesis; Size 25-33. Therefore, optimization of MR imaging parameters to compensate for the presence of this device may be necessary.
| Pulse Sequence | T1-SE | T1-SE | GRE | GRE |
| Signal Void Size | 1,090-mm2 | 686-mm2 | 1,478-mm2 | 1,014-mm2 |
| Plane Orientation | Parallel | Perpendicular | Parallel | Perpendicular |
*The MRI findings apply to this specific largest heart valve prosthesis and all other smaller sizes
which are made from similar materials.
For further information: www.MRIsafety.com, Shellock On-X Life Valve 2010 Report
