Neuroscience 2004 Abstract
| Presentation Number: | 240.8 |
|---|---|
| Abstract Title: | Detection of implantable silicon microelectrodes using MRI at low and high magnetic fields. |
| Authors: |
Martinez Santiesteban, F. M.*1
; Noll, D. C.1
; Bledsoe Jr, S. C.2
; Anderson, D. J.1,2,3
1Biomed. Engin., Univ. of Michigan, Ann Arbor, MI 2Kresge Hearing Res. Inst., Univ. of Michigan, Ann Arbor, MI 3Electrical Engin. and Computer Sci., Univ. of Michigan, Ann Arbor, MI |
| Primary Theme and Topics |
Techniques in Neuroscience - Staining, tracing and imaging techniques |
| Session: |
240. Imaging Techniques: fMRI, BOLD, and Other Poster |
| Presentation Time: | Sunday, October 24, 2004 11:00 AM-12:00 PM |
| Location: | San Diego Convention Center - Hall A-H, Board # GGG19 |
| Keywords: | ANIMAL MODEL, IMPLANT, IN VIVO, LOCALIZATION |
This investigation demonstrates that Magnetic Resonance Imaging (MRI) can be used to determine the localization of implanted multichannel silicon microelectrodes with good spatial resolution, unnoticeable image distortions, and imaging times within acceptable ranges for in vivo studies.
Four-shank 16-channel MRI-compatible silicon microelectrodes, used for neural recording and stimulation of the Central Nervous System (CNS) in animal models, were tested on 9.4 and 2 Tesla (T) animal research magnets.
At high magnetic fields (9.4T), Spin Echo images with in plane resolution of 30μm x 30μm, showed a detectable volume void caused by the individual shanks of the microelectrode, precisely showing its location. At low magnetic fields (2T), Gradient Echo (GE) phase images, with in plane resolution of 100μm x 100μm and after phase unwrapping and image differentiation, showed enough signal dephasing to outline the overall shape of the electrode although individual shanks were not distinguished.
For users or applications where high magnetic fields or high resolutions are not available or required, this study also presents a novel approach that can be used at low magnetic fields and low image resolutions. The method is based on the controlled use of a ferromagnetic material as a contrast agent. Our results showed that a tight control of electroplated nickel in one or two sites of the microelectrode and carefully selected imaging acquisition parameters are required to avoid significant distortions on the images. For GE acquisitions with in plane resolution of 200μm x 200μm, average thickness coating around 0.5μm on site areas of 400μm², and echo time less than or equal to 30ms provided a good tradeoff between electrode localization and acceptable image distortions.
Four-shank 16-channel MRI-compatible silicon microelectrodes, used for neural recording and stimulation of the Central Nervous System (CNS) in animal models, were tested on 9.4 and 2 Tesla (T) animal research magnets.
At high magnetic fields (9.4T), Spin Echo images with in plane resolution of 30μm x 30μm, showed a detectable volume void caused by the individual shanks of the microelectrode, precisely showing its location. At low magnetic fields (2T), Gradient Echo (GE) phase images, with in plane resolution of 100μm x 100μm and after phase unwrapping and image differentiation, showed enough signal dephasing to outline the overall shape of the electrode although individual shanks were not distinguished.
For users or applications where high magnetic fields or high resolutions are not available or required, this study also presents a novel approach that can be used at low magnetic fields and low image resolutions. The method is based on the controlled use of a ferromagnetic material as a contrast agent. Our results showed that a tight control of electroplated nickel in one or two sites of the microelectrode and carefully selected imaging acquisition parameters are required to avoid significant distortions on the images. For GE acquisitions with in plane resolution of 200μm x 200μm, average thickness coating around 0.5μm on site areas of 400μm², and echo time less than or equal to 30ms provided a good tradeoff between electrode localization and acceptable image distortions.
Supported by NIH/NIBIB Grant # P41 EB2030
Sample Citation:
[Authors]. [Abstract Title]. Program No. XXX.XX. 2004 Neuroscience Meeting Planner. San Diego, CA: Society for Neuroscience, 2004. Online.
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