Abstracts

RATIONALE: The objective of this study is to determine the safety of magnetic resonance imaging (MRI) spine imaging in patients implanted with a vagus nerve stimulator (VNS) by using a cold-pack placed over the patient[ssquote]s neck.
METHODS: Three children with medically refractory epilepsy aged 5, 8, and 14 years who had previously been implanted with VNS, underwent MRI spine imaging for evaluation of gait disturbances. Informed consent was obtained in each case. Cervical and thoracic MRI[ssquote]s were performed with a Signa 1.5 Tesla MRI Unit (General Electric; Waukesha, Wisconsin) scanner using standard pulse sequences with a 256x192 Matrix and 2 Nex: 1) Axial T1-weighted Spin Echo (SE) sequence; TR (relaxation time) [ndash] 600, TE (echo time) [ndash] 9; 2) Coronal T1-weighted Fast Spoiled Gras (FSPGR) sequence with a 60-degree flip angle; TR [ndash] 115, TE [ndash] 3.2; 3) Sagittal T1-weighted SE sequence; TR [ndash] 400; TE [ndash] 8. Before scanning, the VNS was programmed to 0 milliampere output for the duty and magnetic activation cycles and a large water and ammonium nitrate cold pack (Allegiance; McGaw Park, Illinois) was placed over the left side of the patient[ssquote]s neck.
RESULTS: High quality spine MRI images were obtained in each case without interference from the VNS generator or stimulation lead. The patients tolerated the procedure without incident.
CONCLUSIONS: The physician[ssquote]s manual for the VNS allows MRI to be performed, but recommends MRI only with use of a transmit and receive head coil. However, some patients implanted with a VNS will inevitably require an MRI scan of the spine using a body coil. In the three patients described here, placing a cold pack over the left side of the neck seemed to protect the vagus nerve from heat that could have theoretically been generated by the body coil MRI. Additional studies can provide greater insight into the safety and feasibility of this method.
(Disclosure: Grant - Cyberonics, Inc., Honoraria - Cyberonics, Inc.)