ABSTRACT
BACKGROUND: This study researched the electric impedance properties of breast tissue and demonstrated the different characteristic of electrical impedance scanning (EIS) images. METHODS: The impedance character of 40 malignant tumors, 34 benign tumors and some normal breast tissue from 69 patients undergoing breast surgery was examined by EIS in vivo measurement and mammography screening, with a series of frequencies set between 100 Hz - 100 kHz in the ex vivo spectroscopy measurement. RESULTS: Of the 39 patients with 40 malignant tumors, 24 showed bright spots, 11 showed dark areas in EIS and 5 showed no specific image. Of the 30 patients with 34 benign tumors there were almost no specific abnormality shown in the EIS results. Primary ex vivo spectroscopy experiments showed that the resistivity of various breast tissue take the following pattern: adipose tissue > cancerous tissue > mammary gland and benign tumor tissue. CONCLUSIONS: There are significant differences in the electrical impedance properties between cancerous tissue and healthy tissue. The impedivity of benign tumor is lower, and is at the same level with that of the mammary glandular tissue. The distinct growth pattern of breast lesions determined the different electrical impedance characteristics in the EIS results.
Subject(s)
Breast Neoplasms/pathology , Breast Neoplasms/diagnosis , Electric Impedance , Female , Humans , MammographyABSTRACT
OBJECTIVE: To testify the feasibility of electrical impedance scanning (EIS) imaging and to classify the factors influencing EIS imaging at the early stage of electrical impedance scanning breast imaging study. METHOD: Based on the EIS experiment workplace, a phantom to simulate the distribution of breast tissue was designed. Using NaCl solution and agar block with different conductance, three kinds of electric fields disturbances were simulated. RESULT: Different electric fields disturbance induced by different conductance distributions bring different imaging effects. CONCLUSION: The imaging based on the theory of EIS is feasible. Initiative factors influencing EIS imaging are confirmed.
Subject(s)
Breast Neoplasms/diagnosis , Electric Impedance , Mammography , Agar , Feasibility Studies , Phantoms, Imaging , Sodium ChlorideABSTRACT
In electrical impedance tomography (EIT), measurements of developed surface potentials due to applied currents are used for the reconstruction of the conductivity distribution. Practical implementation of EIT systems is known to be problematic due to the high sensitivity to noise of such systems, leading to a poor imaging quality. In the present study, the performance of an induced current EIT (ICEIT) system, where eddy current is applied using magnetic induction, was studied by comparing the voltage measurements to simulated data, and examining the imaging quality with respect to simulated reconstructions for several phantom configurations. A 3-coil, 32-electrode ICEIT system was built, and an iterative modified Newton-Raphson algorithm was developed for the solution of the inverse problem. The RMS norm between the simulated and the experimental voltages was found to be 0.08 +/- 0.05 mV (<3%). Two regularization methods were implemented and compared: the Marquardt regularization and the Laplacian regularization (a bounded second-derivative regularization). While the Laplacian regularization method was found to be preferred for simulated data, it resulted in distinctive spatial artifacts for measured data. The experimental reconstructed images were found to be indicative of the angular positioning of the conductivity perturbations, though the radial sensitivity was low, especially when using the Marquardt regularization method.
