Determination of Sensitive Frequency Margin for Aggregated Protein Concentration Quantification by fd-Electrical Impedance Tomography

Abstract A sensitive frequency f margin SFM has been determined for quantification of aggregated interstitial protein concentrations Фprot by frequency difference electrical impedance tomography fd-EIT. Impedances of increasing Фprot of albumin-globulin mixtures in phantoms were measured and changes in protein’s adjacent f point conductivity Δσadj and loss factor Δe“adj plotted against f to determine a Фprot SFM fsen where σadj and e”adj change significantly with Фprot. Results show that the Δσadj and Δe“adj dropped rapidly with increase in f up to f =10 kHz then gradually to f = 100 kHz. The σ and e” were only sensitive to Фprot as f increased from 1 to 10 kHz. For fd-EIT, optimum reference frequency fref was set at 100 kHz. At fsen = 1 kHz against fref, fd-EIT reconstructed σ due to 30% increase in Фprot with area ratio error ARE = 4.1% and a position error PE = 0.1 [-].