Artifact properties of carbon nanotube yarn electrode in magnetic resonance imaging.

OBJECTIVE: Deep brain stimulating (DBS) is a rapidly developing therapy that can treat many refractory neurological diseases. However, the traditional DBS electrodes which are made of Pt-Ir alloy may induce severe field distortions in magnetic resonance imaging (MRI) which leads to artifacts that will lower the local image quality and cause inconvenience or interference. A novel DBS electrode made from carbon nanotube yarns (CNTYs) is brought up to reduce the artifacts. This study is therefore to evaluate the artifact properties of the novel electrode. APPROACH: We compared its MR artifact characteristics with the Pt-Ir electrode in water phantom, including its artifact behaviors at different orientations as well as at various off-center positions, using both spin echo (SE) and gradient echo (GE) sequences, and confirmed its performance in vivo. MAIN RESULTS: The results in phantom showed that the CNTY electrode artifacts reduced as much as 62% and 74% on GE and SE images, respectively, compared to the Pt-Ir one. And consistent behaviors were confirmed in vivo. The susceptibility difference was identified as the dominant cause in producing artifacts. SIGNIFICANCE: Employing the CNTY electrode may generate much less field distortion in the vicinity, improve local MR image quality and possibly be beneficial in various aspects.

A new method of radio frequency links by coplanar coils for implantable medical devices.

A new method based on coplanar coils for the design of radio frequency links has been developed, to realize the communication between the programming wand and the implantable medical devices with shielding container simply and reliably. With the analysis of electronic and magnetic field theory, the communication model has been established and simulated, and the circuit has been designed and tested. The experimental results are consistent with the simulation fairly well. The voltage transfer ratio of the typical circuit with present parameters can reach as high as 0.02, which can fulfill the requirements of communication.

Induction of myelin basic protein-specific experimental autoimmune encephalomyelitis in C57BL/6 mice: mapping of T cell epitopes and T cell receptor V beta gene segment usage.

Early studies of murine experimental autoimmune encephalomyelitis (EAE) induced with myelin basic protein (MBP) divide various mouse strains into either "susceptible" or "resistant" phenotypes. Resistance is defined as lack of encephalitogenic responses after active immunization or adoptive transfer. It is now becoming clear that this unresponsiveness is not due to the inability of T cells to recognize MBP in the context of major histocompatibility complex (MHC) gene products. Using various manipulations, many laboratories are able to induce severe EAE in these strains. We previously reported that a combination of adoptive transfer and subsequent challenge of the recipients with MBP could overcome the resistance in many mouse strains (Shaw et al.: J Neuroimmunol 39:139-150, 1992). This approach now enables us to identify the encephalitogenic epitope and T cell receptor V beta usage in a prototype strain, C57BL/6 (B6). Pepsin-digested MBP fragments first located a major T cell epitope in a polypeptide containing residues 44-88. Overlapping synthetic peptides narrowed this epitope to p60-80. Truncated peptides from the carboxyl- or amino-terminus further mapped a minimal peptide to p67-76. This encephalitogenic epitope appears to be unique to B6 mice. Independent encephalitogenic T cell clones specific for this epitope were also generated. Of six such clones analyzed, five different TCR V beta's were found. Whether unbiased usage of encephalitogenic TCR V beta gene segments in B6 mice is related to its EAE resistant phenotype is not clear at this point.