Neuroscience 2005 Abstract
| Presentation Number: | 456.16 |
|---|---|
| Abstract Title: | The InkCap: measuring EEG at 7 tesla. |
| Authors: |
Vasios, C. E.*1
; Angelone, L. M.1
; Purdon, P.1
; Blood, A.1
; Belliveau, J. W.1
; Bonmassar, G.1
1Dept. of Radiology, Harvard Medical School, Athinoula Martinos Ctr., Charlestown, MA |
| Primary Theme and Topics |
Techniques in Neuroscience - Staining, Tracing, and Imaging Techniques |
| Secondary Theme and Topics | Techniques in Neuroscience<br />- Bioinformatics |
| Session: |
456. Imaging by MRI and PET II Poster |
| Presentation Time: | Monday, November 14, 2005 11:00 AM-12:00 PM |
| Location: | Washington Convention Center - Hall A-C, Board # VV86 |
| Keywords: | EEG/fMRI, 7 Tesla, SAR simulations, Temperature measurements |
OBJECTIVE: During EEG acquisition inside a magnet the generation of induced currents causes several technical and human safety issues. We designed an MRI compatible high resistive-lead EEG cap (InkCap) to reduce Specific Absorption Rate (SAR), improve EEG signal, preserve MRI image quality and enhance subject’s convenience.
METHODS: The InkCap consists of 3 flexible circuit boards with conductive ink microstrips of 2 kΩ/m resistivity. The sensors have half-rings shape to reduce Eddy currents. Evaluation:
1) SAR simulations were performed on a high-resolution human head model for a wide range of microstip resistivity.
2) Temperature measurements on a human head-shaped agarose gel phantom were conducted with Luxtron equipment. High power TSE sequences at 7T were used comparing the InkCap with standard electrodes.
3) EEG acquisition was performed using a custom-made MRI-compatible EEG system with piezoelectric motion sensors.
4) MR imaging was done at 7T.
RESULTS: Simulated SAR values and temperature increase near electrodes were smaller for the InkCap compared to standard electrodes. We acquired clear A-rhythm EEG signal during an eyes open/eyes closed procedure after adaptive filtering. MRI images showed minimum degradation.
CONCLUSIONS: We designed a high-resistive 32 electrode EEG cap using conductive ink technology, tested for safety at 7T. Simulations and temperature measurements confirmed enhanced performance. EEG acquisition in the magnet resulted in clear signals. The use of the InkCap seems to preserve the original MRI image quality. Results of this study show that Ink Cap may improve subject’s safety in very high magnetic field recordings.
METHODS: The InkCap consists of 3 flexible circuit boards with conductive ink microstrips of 2 kΩ/m resistivity. The sensors have half-rings shape to reduce Eddy currents. Evaluation:
1) SAR simulations were performed on a high-resolution human head model for a wide range of microstip resistivity.
2) Temperature measurements on a human head-shaped agarose gel phantom were conducted with Luxtron equipment. High power TSE sequences at 7T were used comparing the InkCap with standard electrodes.
3) EEG acquisition was performed using a custom-made MRI-compatible EEG system with piezoelectric motion sensors.
4) MR imaging was done at 7T.
RESULTS: Simulated SAR values and temperature increase near electrodes were smaller for the InkCap compared to standard electrodes. We acquired clear A-rhythm EEG signal during an eyes open/eyes closed procedure after adaptive filtering. MRI images showed minimum degradation.
CONCLUSIONS: We designed a high-resistive 32 electrode EEG cap using conductive ink technology, tested for safety at 7T. Simulations and temperature measurements confirmed enhanced performance. EEG acquisition in the magnet resulted in clear signals. The use of the InkCap seems to preserve the original MRI image quality. Results of this study show that Ink Cap may improve subject’s safety in very high magnetic field recordings.
Supported by NIH grants RO1 EB002459-01 and P41RR14075
Sample Citation:
[Authors]. [Abstract Title]. Program No. XXX.XX. 2005 Neuroscience Meeting Planner. Washington, DC: Society for Neuroscience, 2005. Online.
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