INSTITUTE OF PHYSICS PUBLISHING PHYSICS IN MEDICINE AND BIOLOGY Phys. Med. Biol. 47 (2002) 857–873 PII: S0031-9155(02)25682-1 In vivo reflectance measurement of optical properties, blood oxygenation and motexafin lutetium uptake in canine large bowels, kidneys and prostates Michael Solonenko 1,2,4 , Rex Cheung 1,2 , Theresa M Busch 2 , Alex Kachur 2 , Gregory M Griffin 3 , Theodore Vulcan 1,2 , Timothy C Zhu 2 , Hsing-Wen Wang 1,2 , Stephen M Hahn 2 and A G Yodh 1,2 1 Department of Physics & Astronomy, University of Pennsylvania, Philadelphia, PA 19104, USA 2 Department of Radiation Oncology, University of Pennsylvania, Philadelphia, PA 19104, USA 3 School of Veterinary Medicine, University of Pennsylvania, Philadelphia, PA19104, USA E-mail: yodh@dept.physics.upenn.edu Received 12 June 2001 Published 1 March 2002 Online at stacks.iop.org/PMB/47/857 Abstract Motexafin lutetium (MLu) is a second-generation photosensitizer for photodynamic therapy (PDT) of cancer. We have developed and applied a diffuse optical reflectance spectrometer for in vivo measurement of MLu uptake, optical properties, haemoglobin concentration and haemoglobin oxygen saturation in normal canine large bowels, kidneys and prostates. The probe consists of a broadband fibre-optic-coupled light source and detector fibres placed at various distances from the source fibre to collect reflected light. An analysis based on the diffusion approximation of the photon transport equation was used to recover tissue optical properties from the reflectance measurements. The instrumentation and analysis methods were validated using measurements from homogeneous, highly scattering phantoms with known MLu concentrations. The same techniques were then used to estimate chromophore concentrations of normal canine large bowels, kidneys and prostates. We estimated (mean (standard deviation)) total haemoglobin concentrations of 119 (25), 340 (92) and 51 (11) µM in the large bowels, kidneys and prostates of four dogs,respectively; tissue blood oxygen saturations in these same organs were 75 (15), 76 (21) and 74 (16) per cent, respectively. Tissue MLu concentrations (mg l -1 ) were estimated from data taken 3.5 h after injection of a 2 mg kg -1 injected dose; data from three dogs gave concentrations of 2.4 (0.4) in large bowels, 6.8 (1.3) in kidneys and 2.2 (1.1) in prostates. The reduced scattering coefficients, µ ′ s , estimated for large bowels, kidneys 4 Present address: Advent Optronics Corporation, 205 Pheasant Run, Newtown, PA 18940, USA. 0031-9155/02/060857+17$30.00 © 2002 IOP Publishing Ltd Printed in the UK 857