Near infrared spectroscopy evaluation of bladder function: the impact of skin pigmentation on detection of physiologic change during voiding. Babak Shadgan a,b* , Lynn Stothers a,b , Behnam Molavi c , Sharif Mutabazi d , Ronald Mukisa e , Andrew Macnab b,d a Centre for International Collaboration on Repair Discoveries, Vancouver, Canada. b Department of Urologic Sciences, University of British Columbia, Vancouver, Canada. c Department of Electrical Engineering and Computing, University of British Columbia, Vancouver, Canada. d Cure Medical Centre, Ishaka, Uganda. e Stellenbosch Institute for Advanced Study (STIAS), Wallenberg Research Centre, Stellenbosch, South Africa. ABSTRACT Background: Prior research indicates the epidermal pigment layer of human skin (Melanin) has a significant absorption coefficient in the near infra-red (NIR) region; hence attenuation of light in vivo is a potential confounder for NIR spectroscopy (NIRS). A NIRS method developed for transcutaneous evaluation of bladder function is being investigated as a means of improving the burden of bladder disease in sub-Saharan Africa. This required development of a simple wireless NIRS device suitable for use as a screening tool in patients with pigmented skin where the NIR light emitted would penetrate through the epidermal pigment layer and return in sufficient quantity to provide effective monitoring. Methods: Two healthy subjects, one with pigmented skin and one with fair skin, were monitored as they voided spontaneously using the prototype transcutaneous NIRS device positioned over the bladder. The device was a self-contained wireless unit with light emitting diodes (wavelengths 760 and 850 nanometres) and interoptode distance of 4cm. The raw optical data were transmitted to a laptop where graphs of chromophore change were generated with proprietary software and compared between the subjects and with prior data from asymptomatic subjects. Results: Serial monitoring was successful in both subjects. Voiding volumes varied between 350 and 380 cc. In each subject the patterns of chromophore change, trend and magnitude of change were similar and matched the physiologic increase in total and oxygenated hemoglobin recognized to occur in normal bladder contraction during voiding. Conclusions: Skin pigmentation does not compromise the ability of transcutaneous NIRS to interrogate physiologic change in the bladder during bladder contraction in healthy subjects. Key words: Bladder, Chromophore, Melanin, Near-infrared Spectroscopy, Skin Pigmentation Send correspondence to: * Babak Shadgan MD, MSc, PhD E-mail: shadgan@alumni.ubc.ca Photonic Therapeutics and Diagnostics XI, edited by Bernard Choi, et al., Proc. of SPIE Vol. 9303, 93030U · © 2015 SPIE · CCC code: 1605-7422/15/$18 · doi: 10.1117/12.2077824 Proc. of SPIE Vol. 9303 93030U-1 Downloaded From: http://spiedigitallibrary.org/ on 03/12/2015 Terms of Use: http://spiedl.org/terms