Project ID:2015s08
Year:2015
Students:Adam Goldfeld, Shai Tzroia
Supervisor:Nemirovsky-Rotman Shira
Tags:
Downloads:

(Link to project documentation folder to be placed here)

MAET – MAGNETO ACOUSTO ELECTRICAL TOMOGRAPHY

Hybrid Tomography Modalities

  • Today, a variety of Tomography Modalities exists based on different physical aspects
  • Each serves a purpose while having drawbacks:
    • MRI – long acquisition time, expensive
    • CT – safety issues due to radiation
    • US – low contrast
    • EIT – low resolution, not stable
  • Hybrid Modalities offer to combine the advantages of existing modalities while reducing drawbacks

 

The MAET modality

  • Good contrast
  • High Resolution
  • Stable2015s05_1
  • Safe
  • None-Invasive
  • Cheap
 

The Forward and Inverse problems

  • We can separate the MAET tomography into two problems
  • The Forward problem:

A model of the expected measurements, given the tissue’s impedance

  • The Inverse problem:

The tissue’s impedance reconstruction,  given the measurements

 

Project Goals

  • We restrict ourselves to the Forward problem only
  • Our goals are:
  1. Understand the MAET forward problem theory model
  2. Develop numeric tools specified to solve the forward problem
  3. Build a working model simulation of the MAET measurement
  4. Give predictions for future experiments
  • The project will help in providing a database for the Inverse problem solution validation
  • Moreover, the project will provide a starting point for future experiments settings
 

Projects Highlights

  • Literature review of MAET Physical and mathematical model
  • Implementation of the mathematical model in Matlab
  • Implementation in Comsol
  • Three tissue models
  • Matlab-Comsol interface
  • MAET measurement simulation
  • Parametric sweep study
 

Simulations Results-Circular

2015s05_2.png

Simulations Results-Elliptic

2015s05_3.png

Simulations Results-Multi

2015s05_4.png

 

Simulation Conclusions

  • The conductivity map is the main factor which determines the measurement profile
  • Different model width leads to measurement scaling
  • Variation in Electrodes size has negligible effect
  • Variation in Electrodes position results in different measurement profile
  • Dispersion has minor effect on measurement profile
  • Expected voltage scale is in milliVolt to microVolt  ,time in microseconds
 

Summary

  • Hybrid tomography modalities
  • MAET forward problem formulation and theory
  • Implementation of Poisson solver in Matlab in different coordinate systems
  • Maet simulation in Matlab
  • Comsol usage and integration with Matlab
  • Various tissue models simulation and comparisons
  • Experiment oriented conclusion
 

Further Study

  • Detailed ultrasound model
  • Theory validation in a real world experiment
  • MAET inverse problem simulation
 

Forward Problem Theory

  • Starting assumptions:
    • Quasi-staticRegime
    • Ultrasound wave can be focused on to a very small volume
    • Controllable constant magnetic field
    • Tissue electro-neutrality
    • No outgoing current in tissue boundary beside probes
 

 References

  • S. Haider, a Hrbek, and Y. Xu, “Magneto-acousto-electrical tomography: a potential method for imaging current density and electrical impedance.,” Physiol. Meas., vol. 29, no. 6, pp. S41–S50, 2008.
  • H. A. Haus and J. R. Melcher, “Electromagnetic Fields and Energy,” Massachusetts Institute of Technology. [Online]. Available: http://web.mit.edu/6.013_book/www/chapter7/7.2.html. [Accessed: 07-Sep-2015].
  • L. N. Dworsky, Introduction to Numerical Electrostatics Using MATLAB, 1st Edition. Wiley-IEEE Press, 2014.