Characterisation of human bladder urothelium using electrical impedance spectroscopy
Bladder cancer is the most common malignancy in elderly people. In developed countries most bladder cancers are transitional cell carcinomas (TCC). This is a cancer of the urothelium (a transitional epithelium lining the bladder). In the UK there are approximately 13,000 new cases and 5400 deaths per annum (Black, Bray et al. 1997). Carcinoma in situ (CIS) is an early case of the invasive cancer, which is flat, nonpapillary and difficult to detect precisely by using common methods. It is an aggressive form of TCC which may progress to muscle invasive cancer. Bladder pathology is usually investigated visually by cystoscopy. Erythematous areas of the urothelium are usually observed but these can represent different conditions ranging from simple inflammation to flat CIS. CIS cannot be differentiated visually from other erythematous tissues. Biopsies must be taken from the suspect area to obtain diagnostic information. The selection of biopsy sites depends on simple visual inspection thus is effectively random, and can be negative in up to 90% of the patients (van der Meijden, Oosterlinck et al. 1999). This is a relatively high cost procedure in terms of both time and money and is associated with discomfort for the patient and morbidity. Electrical impedance spectroscopy (EIS) is a non-invasive screenIng technique to separate malignant areas from non-malignant areas in the urinary bladder. This is a result of the electrical impedance spectrum of the tissue being a function of tissue structure at the cellular level. The feasibility of adapting this minimally invasive technique to screen for bladder cancer, CIS during cystoscopy has been explored and compared with histopathological evaluation of urinary bladder lesions, both ex vivo and in vivo. Finite element modelling technique have been used to explore the relationship between urothelial morphology and the impedance spectrum. Both measured and modelled results showed that this technique is able to separate benign and malignant bladder tissue groups and the in vivo measurements suggest that classification of individual measurements should be possible.