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.