User's Manual

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Communication is maintained with the patient so that the scan can be promptly
terminated in the event of painful nerve stimulation or other adverse event.
Information regarding the position of the lead is necessary for routine MRI procedures. Review
of the patient’s Medical Device Identification Card, direct communication with the implanting
physician or obtaining an x-ray is recommended to determine the location of the implanted lead.
Patients must be screened for previously implanted (active or abandoned) medical devices,
leads, lead extenders or lead adapters.
MRI-Related Heating: Supplemental Information
1.5 T/64 MHz
Temperature changes of the electrodes of the StimRouter lead were measured at 1.5 T/64 MHz
according to ASTM F2182 (GE Signa, 46- 258170G1, whole body transmit radio frequency
(RF) coil). With the lead in an orientation and a position in the phantom to produce worst-case
heating, the greatest measured temperature rise scaled to a background local SAR of 1 W/kg
was 3.9°C after six minutes of RF power application. This temperature change was with the lead
in an elongated, “straight” configuration (i.e., no curves), which produced the highest temperature
change. With the lead in curved or looped configurations, temperature changes were less.
A computer simulation that incorporated the worst-case measured rise and a whole-body-averaged
SAR of 2 W/kg predicts a worst case in the patient during MRI of less than 2°C provided that
the entire StimRouter lead is at least 50 cm from the center of the bore of the MR system and at
least 16 cm outside of the MR coil measured from the edge of the MR coil.
3 T/128 MHz
Temperature changes of the electrodes of the StimRouter lead were measured at 3 T/128 MHz
according to ASTM F2182 (GE Signa, 3T HDx, Software Version 15/LX/MR, 15.0.M4.0910a).
With the lead in an orientation and a position in the phantom to produce worst-case heating, the
greatest measured temperature rise scaled to a local background SAR of 2 W/kg was 2.9°C after
six minutes of RF power application. This temperature change was with the lead in an elongated,
“straight” configuration (i.e., no curves), which produced the highest temperature change. With
the lead in curved or looped configurations, temperature changes were less.
A computer simulation that incorporated the worst-case measured rise and a whole-body-averaged
SAR of 2 W/kg predicts a worst case in the patient during MRI of less than 1°C provided that
the entire StimRouter lead is at least 50 cm from the center of the bore of the MR system and at
least 16 cm outside of the MR coil measured from the edge of the MR coil.
Chapter 2 - Warnings and Cautions
7