Electrical impedance tomography

Last revised by Joachim Feger on 27 Apr 2024

Citation, DOI, disclosures and article data

Citation:

Moore C, Feger J, Electrical impedance tomography. Reference article, Radiopaedia.org (Accessed on 03 May 2024) https://doi.org/10.53347/rID-188026

DOI:

https://doi.org/10.53347/rID-188026

Permalink:

https://radiopaedia.org/articles/188026

rID:

188026

Article created:

20 Apr 2024, Candace Makeda Moore

Disclosures:

At the time the article was created Candace Makeda Moore had no financial relationships to ineligible companies to disclose.

View Candace Makeda Moore's current disclosures

Last revised:

27 Apr 2024, Joachim Feger ◉

Disclosures:

At the time the article was last revised Joachim Feger had no financial relationships to ineligible companies to disclose.

View Joachim Feger's current disclosures

Revisions:

4 times, by 2 contributors - see full revision history and disclosures

Sections:

Imaging Technology

Synonyms:

Electrical impedance tomography (EIT)
Dual-ferquency electrical impedance tomography (dfEIT)
Multi-ferquency electrical impedance tomography (mfEIT)

Electrical impedance tomography (EIT) is a type of imaging based on sending small amounts of electrical current across tissue (when used for medical imaging) and measuring conductivity.

There are several ways in which the EIT signal can be generated and processed, and these are often indicated by a specific name, which is typically written as an acronym. The signal can be single, dual (dfEIT) or multi-frequency (mfEIT). Processing may allow examination of absolute EIT signal (aEIT), frequency difference (fdEIT) or time difference EIT signal (tdEIT).

Clinical applications

In some advanced centers, the technique is used to monitor the lungs of critically ill patients. It should be noted that while EIT can theoretically be used with diverse applications from monitoring peristalsis to intrinsic brain activity to clots and thrombi ¹, it is not typically used for such activities as other modalities allow for superior imaging. There is active research in applying the technique in clinical neuroimaging³and breast cancer detection ⁴.

Contraindications

The technique should not be used on patients with pacemakers, implantable cardiac defibrillators (ICDs) or any implanted devices. Thoracic EIT machines should not be used on patients who have unstable rib or spinal fractures as applying the EIT belt requires moving the patients. At present there is much less quality in EIT signal measurements on extremely obese patients, so extreme obesity is relative contraindication.

Technique

Electrical impedance tomography measurements are done with electrodes around the object measured, and reconstruction algorithms are used to create tomographic images. The technique can allow for continuous imaging over the time it is applied.

The advantages of the technique in a clinical setting are the lack of radiation and low cost.

Interpretation

Pitfalls and artifacts

In EIT lung imaging the stronger electrical signal of the heart creates significant artifacts which at present are not well controlled with signal processing techniques.

History and etymology

Developments which allowed for EIT can be traced back to at least the 1930s, however the published application of these technologies to the body began in the 1970s, with many crediting John Webster ⁵ for this.