Virtual bladder biopsy by electrical impedance measurements (62.5 Hz-1.5 MHz)

Abstract

Bladder pathology is usually investigated visually by cystoscopy and in this technique, erythematous areas of the human urothelium are usually seen by eye. However, these can represent different conditions ranging from simple inflammation to flat carcinoma-in-situ (CIS). Definitive diagnosis can be made by biopsy only, usually under general anaesthesia. The selection of biopsy sites depends on simple visual inspection thus is effectively random, and can be negative sometimes. This is a relatively high cost procedure in terms of both time and money and is associated with discomfort for the patient and morbidity. Therefore, the feasibility of adapting a minimally invasive technique to screen for bladder cancer has been explored and compared with histopathological evaluation of urinary bladder lesions at lower frequencies. However, the tight junctions of the epithelium affect the bladder tissue impedances at lower frequencies more than at higher frequencies. Thus, a low frequency impedance system, 62.5 Hz-1.5 MHz was used to investigate a good separation of impedance between malignant and benign areas of the bladder. The measured data of the bladders were separated using the pathological reports. After analyzing these data, there was found a significant difference between benign and malignant areas of the bladder especially at lower frequencies (p < 0.0001). These results demonstrate the potential of electrical impedance system for developing a novel and minimally invasive tool for the identification, selection for sampling, screening and possible diagnosis of flat bladder lesions.