Measurement of a 2D electric dipole field using the acousto-electric effect

Ragnar Olafsson, Russell S. Witte, Matthew O'Donnell

Research output: Chapter in Book/Report/Conference proceedingConference contribution

8 Scopus citations

Abstract

Conventional methods for mapping cardiac current fields have either poor spatial resolution (e.g. ECG) or are time consuming (e.g., intra-cardiac catheter electrode mapping). We present a method based on the acousto-electric effect (AEE) and lead field theory for minimally-invasive mapping of 2D current distributions. The AEE is a pressure-induced conductivity modulation in which focused ultrasound can be used as a spatially-localized pressure source. As a proof of principle we generated a 2D dipole field in a thin bath of 0.9% NaCl solution by injecting 28 mA through a pair of electrodes. A 7.5 MHz transducer was focused on the bath from below. A recording electrode was rotated along the boundary of the bath in 20° steps. For each angle, the transducer was swept over the bath in a raster scan. A pulse-echo and an AEE voltage trace were acquired at each point. The AEE traces were combined in post-processing as if coming from a multi-electrode circular array. The direction and magnitude of the current field at each point in the plane was estimated from the AEE and compared to simulation. The potential field was independently mapped using a roving monopolar electrode. The correlation coefficient between this map and the simulated field was 0.9957. A current source density analysis located the current source and sink to within 1±2 mm of their true position. This method can be extended to 3 dimensions and has potential for use in rapid mapping of current fields in the heart with high spatial resolution.

Original languageEnglish (US)
Title of host publicationMedical Imaging 2007
Subtitle of host publicationUltrasonic Imaging and Signal Processing
DOIs
StatePublished - Oct 15 2007
Externally publishedYes
EventMedical Imaging 2007: Ultrasonic Imaging and Signal Processing - San Diego, CA, United States
Duration: Feb 18 2007Feb 19 2007

Publication series

NameProgress in Biomedical Optics and Imaging - Proceedings of SPIE
Volume6513
ISSN (Print)1605-7422

Other

OtherMedical Imaging 2007: Ultrasonic Imaging and Signal Processing
CountryUnited States
CitySan Diego, CA
Period2/18/072/19/07

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Keywords

  • Acousto-electric
  • Cardiac
  • Conductivity
  • Current
  • Dipole
  • Distribution
  • Electrocardiography
  • Mapping
  • Ultrasound

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Biomaterials
  • Atomic and Molecular Physics, and Optics
  • Radiology Nuclear Medicine and imaging

Cite this

Olafsson, R., Witte, R. S., & O'Donnell, M. (2007). Measurement of a 2D electric dipole field using the acousto-electric effect. In Medical Imaging 2007: Ultrasonic Imaging and Signal Processing [65130S] (Progress in Biomedical Optics and Imaging - Proceedings of SPIE; Vol. 6513). https://doi.org/10.1117/12.712448