Ankle Configuration
• A maximum temperature increase of 2.1 °C has been measured at the tip of the indicated screw (Maximum Whole Body averaged SAR
of 2W/kg for 6 minutes of scanning)
• At the indicated clamp a temperature increase of 12.2 °C (with reference to room temperature) has been measured
Code Description
1x92125 Rod 125mm long
1x92175 Rod 175mm long
1x92275 Rod 275mm long
2x911540 Self-Drilling XCaliber Screw, L. 150mm, thread length 40mm
1x92080 Transfixing Pin, thread length 80mm, thread Ø 5mm, shaft Ø 4mm
2x92016 Blue Screw Clip Clamp
2x92012 Blue Rod Clip Clamp
2x92026 Blue Transfixing Pin Clamp
These tests have been performed in areas where the greatest temperature increase is expected with commonly used frames: at the tip and
surrounding the tip of the most external screw. Due to the versatility of the system, an unlimited number of frames can be built which makes
it impossible to test every construct.
There are factors that can influence these results (e.g. the number of screws used). Therefore, it is recommended that each frame be evaluated
by a radiologist or MR scientist before the MRI procedure is undertaken to ensure patient safety. Since different frame configurations and
frame sizes might lead to higher temperature increases, Orthofix recommends that the SAR settings are minimised as much as possible.
None of the components should move or migrate in the 1.5 Tesla MRI environments. Non-clinical testing has not been performed to rule out the possibility
of component movement or migration at static magnetic field strengths higher than 1.5 Tesla or maximum spatial gradients higher than 9.37mT/m.
IMAGE ARTIFACTS
MR image quality may be compromised if the area of interest is in the same vicinity or relatively close to the position of the device. Therefore,
it may be necessary to optimize MR imaging parameters for the presence of this implant. Representative components used to assemble Prefix
2
have been evaluated in MRI chamber. Typical values of artifacts sizes are reported below.
4
Code Description
1x92275 Rod 275mm long
1x92012 Blue Rod Clip Clamp
1x92016 Blue Screw Clip Clamp
1x911560 Self-Drilling XCaliber Screw, L. 150mm, thread length 60mm
Pulse Sequence Spin-echo Gradient-echo
TR (ms) 500 334
TE (ms) 4,8 4,6
Slice Thickness (mm) 5 5
Matrix size 230x288 230x288
Flip Angle 90° 30°
Imaging Plane perpendicular to static field perpendicular to static field
Artifact Size (mm) 16 34
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