Available online at www.sciencedirect.com Medical Engineering & Physics 30 (2008) 693–699 Surface fluids effects on the bladder tissue characterisation using electrical impedance spectroscopy Ahmad Keshtkar a,∗ , Asghar Mesbahi a , Parinaz Mehnati a , Asghar Keshtkar b a Medical Physics Department, Medical School, Tabriz University of Medical Sciences, Tabriz, Iran b Electrical and Computer Engineering Faculty, Tabriz University, Tabriz, Iran Received 24 February 2007; received in revised form 5 July 2007; accepted 17 July 2007 Abstract The electrical impedance of the human urinary bladder in both benign and malignant areas can be measured using an electrical impedance spectroscopy system (EIS). Glycine is usually used in the bladder surgery in the theatre to make an insulation medium for electro-surgery and the extension of the mucosa. In addition, a saline solution is usually used to wash the inside of the bladder after bladder surgery and it is used to extend the bladder tissue mucosa. Therefore, the effect of glycine and the saline solution that fills the bladder is important, because it was expected that the application of common surface fluids (air, saline solution and glycine solution) in the bladder epithelium would affect the measured electrical impedance of the urothelium, to differentiate the malignant area from the normal bladder tissue. In this study, bladders were removed from the patients’ bodies and then were moved from theatre to the histopathology department immediately after excision. These bladder samples were then opened and pinned to a corkboard to take the impedance readings, using the impedance spectroscopy system. Following this, the bladder and corkboard were completely submerged in a saline solution and readings were taken at about 1 cm from the sutures. Subsequently, this procedure was repeated with the bladder submerged in glycine and then air, respectively. According to the statistical work, these fluids were found to have a significant effect on the measured impedance of the bladder tissue in benign and malignant areas. Furthermore, the best fluid between air, glycine and saline, to measure the impedance of the urinary bladder, is air (P < 0.0001). © 2007 IPEM. Published by Elsevier Ltd. All rights reserved. Keywords: Air; Bladder tissue; Electrical impedance; Surface fluids; Glycine and saline 1. Introduction In endoscopic operations for bladder abnormalities, sur- geons usually use an irrigating fluid for both washing and the extension of the mucosa. A previous review article of these surface fluids in endoscopic surgery summarizes a number of reports [1]. In addition, it is important to review the progress that has been made to understand the effects of these flu- ids. Historically, sterile water has been used to irrigate the inside of the urinary bladder during the electro-cutting pro- cedure. However, the electrolytes do not allow the cutting of the tumours from the bladder wall in this method. There- fore, glycine was used as an electrical insulation using the electro-surgery procedure. Moreover, the saline solution is ∗ Corresponding author. Tel.: +98 411 3364660. E-mail address: mpp98ak@hotmail.com (A. Keshtkar). usually used as irrigating fluid in the bladder after removing the tumours, using the electro-surgery operation. Because of the common application of some surface fluids during blad- der surgery, the in vivo and ex vivo impedance readings were taken under this condition in this study. There are a number of studies in the field of electrical impedance spectroscopy. One example is that which concerned the relation between tissue structures and an imposed electrical flow in cervical neoplasia, to compare the impedance of normal and abnor- mal cervical tissues [2]. Another study investigated virtual biopsies in Barrett’s oesophagus, using electrical impedance measurements [3]. The aim of their study was to show the possibility of differentiating two types of epithelia (squa- mous and columnar) in terms of their electrical impedances. In addition, it has been proposed that electrical impedance spectroscopy can detect bladder malignancy, using low and high frequencies [4–6]. The aim of this paper is to find the 1350-4533/$ – see front matter © 2007 IPEM. Published by Elsevier Ltd. All rights reserved. doi:10.1016/j.medengphy.2007.07.008