MREIT of Postmortem Swine Legs using Carbon-hydrogel Electrodes
1
조회
0
다운로드
4
인용
0
참고문헌
키워드
초록
Magnetic resonance electrical impedance tomography (MREIT) has been suggested to produce cross-sectional conductivity images of an electrically conducting object such as the human body. In most previous studies, recessed electrodes have been used to inject imaging currents into the object. An MRI scanner was used to capture induced magnetic flux density data inside the object and a conductivity image reconstruction algorithm was applied to the data. This paper reports the performance of a thin and flexible carbon-hydrogel electrode that replaces the bulky and rigid recessed electrode in previous studies. The new carbon-hydrogel electrode produces a negligible amount of artifacts in MR and conductivity images and significantly simplifies the experimental procedure. We can fabricate the electrode in different shapes and sizes. Adding a layer of conductive adhesive, we can easily attach the electrode on an irregular surface with an excellent contact. Using a pair of carbon-hydrogel electrodes with a large contact area, we may inject an imaging current with increased amplitude primarily due to a reduced average current density underneath the electrodes. Before we apply the new electrode to a human subject, we evaluated its performance by conducting MREIT imaging experiments of five swine legs. Reconstructed conductivity images of the swine legs show a good contrast among different muscles and bones. We suggest a future study of human experiments using the carbon-hydrogel electrode following the guideline proposed in this paper
Abstract
Magnetic resonance electrical impedance tomography (MREIT) has been suggested to produce cross-sectional conductivity images of an electrically conducting object such as the human body. In most previous studies, recessed electrodes have been used to inject imaging currents into the object. An MRI scanner was used to capture induced magnetic flux density data inside the object and a conductivity image reconstruction algorithm was applied to the data. This paper reports the performance of a thin and flexible carbon-hydrogel electrode that replaces the bulky and rigid recessed electrode in previous studies. The new carbon-hydrogel electrode produces a negligible amount of artifacts in MR and conductivity images and significantly simplifies the experimental procedure. We can fabricate the electrode in different shapes and sizes. Adding a layer of conductive adhesive, we can easily attach the electrode on an irregular surface with an excellent contact. Using a pair of carbon-hydrogel electrodes with a large contact area, we may inject an imaging current with increased amplitude primarily due to a reduced average current density underneath the electrodes. Before we apply the new electrode to a human subject, we evaluated its performance by conducting MREIT imaging experiments of five swine legs. Reconstructed conductivity images of the swine legs show a good contrast among different muscles and bones. We suggest a future study of human experiments using the carbon-hydrogel electrode following the guideline proposed in this paper
참고문헌 (23)
- N. Zhang, "Electrical Impedance Tomography based on Current Density Imaging" (1992), Toronto, Canada: MS Thesis, Dept. of Elec. Eng
- E.J. Woo, "Impedance tomography using internal current density distribution measured by nuclear magnetic resonance", SPIE, 2299, pp.377~385 (1994)
- Y.Z. Ider, "Use of the magnetic field generated by the internal distribution of injected currents for electrical impedance tomography (MR-EIT)", Elektrik, 6, pp.215~225 (1998)
- O. Kwon, "Magnetic resonance electrical impedance tomography (MREIT): simulation study of J-substitution algorithm", IEEE Trans. Biomed. Eng, 49, pp.160~167 (2002)
- E.J. Woo, "Magnetic resonance electrical impedance tomography (MREIT) in Holder D ed" (2005), Electrical Impedance Tomography: Methods, History and Applications, Bristol, UK: IOP Publishing
- H.J. Kim, "Conductivity imaging of canine brain using a 3 T MREIT system: postmortem experiments", Physiol. Meas, 28, pp.1341~1353 (2007)
- H.J. Kim, "In vivo electrical conductivity imaging of a canine brain using a 3T MREIT system", Physiol. Meas, 29, pp.1145~1155 (2008)
- B.I. Lee, "Three-dimensional forward solver and its performance analysis in magnetic resonance electrical impedance tomography (MREIT) using recessed electrodes", Phys. Med. Biol, 48, pp.1971~1986 (2003)
- S.H. Oh, "Conductivity and current density image reconstruction using harmonic Bz algorithm in magnetic resonance electrical impedance tomography", Phys. Med. Biol, 48, pp.3101~3116 (2003)
- S.H. Oh, "Magnetic resonance electrical impedance tomography at 3 Tesla field strength", Mag. Reson. Med, 51, pp.1292~1296 (2004)
- S.H. Oh, "Electrical conductivity images of biological tissue phantoms in MREIT", Physiol. Meas, 26, pp.279~288 (2005)
- T.I. Oh, "Validation of a multi-frequency electrical impedance tomography(mfEIT)system KHU Mark1:impedance spectroscopy and time-difference imaging", Physiol. Meas, 29, pp.295~307 (2008)
- C. Park, "Measurement of induced magnetic flux density using injection current nonlinear encoding(ICNE)in MREIT", Physiol. Meas, 28, pp.117~127 (2006)
- Tong In Oh, "Improved Current Source Design to Measure Induced Magnetic Flux Density Distributions in MREIT", 의공학회지, 27(1), pp.30~37 (2006), 대한의용생체공학회
- R. Sadleir, "Noise analysis in MREIT at 3 and 11 Tesla field strength", Physiol. Meas, 26, pp.875~884 (2005)
- J.K. Seo, "Reconstruction of conductivity and current density images using only one component of magnetic field measurements", IEEE Trans. Biomed. Eng, 50, pp.1121~1124 (2003)
- L.A. Geddes, "The specific resistance of biolo-gical material:a compendium of data for the biomedical engineer and physiologist", Med. Biol. Engng, 5, pp.271~293 (1967)
- C. Gabriel, "The dielectric properties of biological tissues: I. literature survey", Phys. Med. Biol, 41, pp.2231~2249 (1996)
- S. Gabriel, "The dielectric properties of biological tissues: II. measurements in the frequency range 10Hz to 20GHz", Phys. Med. Biol, 41, pp.2251~2269 (1996)
- S. Grimnes, "Bioimpedance and Bioelectr- icity Basics" (2000), London, UK: Academic Press
- G.C. Scott, "Measurement of nonuniform current density by magnetic resonance", IEEE Trans. Med. Imag, 10, pp.362~374 (1991)
- G.C. Scott, "Sensitivity of magnetic resonance current density imaging", J. Magn. Reson, 97, pp.235~254 (1992)
- S.H. Lee, "Conductivity image reconstruction from defective data in MREIT:numerical simulation and animal experiment", IEEE Trans. Med. Imag, 25, pp.168~176 (2006)