Electrical impedance spectroscopy and the diagnosis of bladder pathology

Abstract

Bladder pathology is usually investigated visually by cystoscopy. At present, definitive diagnosis of the bladder can be made by biopsy only, usually under general anaesthesia. This is a relatively high-cost procedure in terms of both time and money and is associated with discomfort for the patient and morbidity. Thus, we used an electrical impedance spectroscopy technique for differentiating pathological changes in the urothelium and improving cystoscopic detection. For ex vivo study, a whole or part of the patient's urinary bladder was used to take the readings less than half an hour after excision at room temperature, about 27 degrees C, using the Mk3.5 Sheffield System (2-384 kHz in 24 frequencies). In this study, 145 points (from 16 freshly excised bladders from patients) were studied in terms of their biopsy reports matching to the electrical impedance measurements. For in vivo study, a total of 106 points from 38 patients were studied to take electrical impedance and biopsy samples. The impedance data were evaluated in both malignant and benign groups, and revealed a significant difference between these two groups. The impedivity of the malignant bladder tissue was significantly higher than the impedivity of the benign tissue, especially at lower frequencies (p < 0.001). In addition, the receiver operating characteristic (ROC) curve for impedance measurements indicated that this technique could provide diagnostic information (individual classification is possible). Thus, the authors have investigated the application of bio-impedance measurements to the bladder tissue as a novel and minimally invasive technique to characterize human bladder urothelium. Therefore, this technique, especially at lower frequencies, can be a complementary method for cystoscopy, biopsy and histopathological evaluation of the bladder abnormalities.

Compression-dependency of soft tissue bioimpedance for in-vivo and in-vitro tissue testing

“…Jossinet compared the complex impedance loci of normal and carcinoma in a frequency range of 488 Hz to 1 MHz and an obvious difference was observed in the shape and location of the loci at frequencies above 125 kHz for normal, benign and carcinoma tissue. Keshtkar et al performed electrical impedance measurements on 38 invivo benign and malignant subjects at a frequency range of 2-348 kHz [20]. The results revealed that the impeditivity of malignant subjects were significantly higher than the impeditivity of benign subjects which was in contrast to the results presented by Brown et al [21] and Gonzales-Correa [22].…”

The feasibility of computational modelling technique to detect the bladder cancer

“…the impedance spectra) obtained from the model with those obtained experimentally for both normal and malignant cases. There is a study by authors that explains how we can measure the electrical impedance data of the human bladder tissue [7]. However, the current flowing through every node located on the boundary midway between the two drive electrodes can also be calculated and then integrated to give the total current flowing through each layer.…”

“…However, authors carried out a study about the bio impedance measurement of the bladder tissue [7] and introduced the electrical impedance spectroscopy as a new technique to detect of bladder pathology. Then, they modelled the current distribution inside the normal and malignant human urothelium and discussed about this modelled results according to the current distribution in different layers of the urothelium [4,5].…”

Micro electrical impedance spectroscopy on a needle for ex vivo discrimination between human normal and cancer renal tissues

“…Many studies have reported significant differences in electrical impedance, using the EIS devices, between dissimilar cells or tissues from various organs. [12][13][14][15][16][17] Despite the availability of EIS probes in tumor detection, it is inappropriate for detecting completely buried endophytic tumors and estimating tumor depth from the surface of the organ. On the other hand, the lEoN is a needle with EIS incorporated on its tip, which enables the device to penetrate through the tissues and reach the tumor, as well as the deepest margin between the tumor and normal tissues.…”