title: Towards pH-sensitive imaging of small animals with photon-counting difference diffuse fluorescence tomography.
abstract: The importance of cellular pH has been shown clearly in the study of cell activity, pathological feature, and drug metabolism. Monitoring pH changes of living cells and imaging the regions with abnormal pH-values, in vivo, could provide invaluable physiological and pathological information for the research of the cell biology, pharmacokinetics, diagnostics, and therapeutics of certain diseases such as cancer. Naturally, pH-sensitive fluorescence imaging of bulk tissues has been attracting great attentions from the realm of near infrared diffuse fluorescence tomography (DFT). Herein, the feasibility of quantifying pH-induced fluorescence changes in turbid medium is investigated using a continuous-wave difference-DFT technique that is based on the specifically designed computed tomography-analogous photon counting system and the Born normalized difference image reconstruction scheme. We have validated the methodology using two-dimensional imaging experiments on a small-animal-sized phantom, embedding an inclusion with varying pH-values. The results show that the proposed approach can accurately localize the target with a quantitative resolution to pH-sensitive variation of the fluorescent yield, and might provide a promising alternative method of pH-sensitive fluorescence imaging in addition to the fluorescence-lifetime imaging.
authors.affiliation: Tianjin University, College of Precision Instruments and Optoelectronics Engineering, Tianjin 300072, China. jiaoli@tju.edu.cn
authors.forename: Jiao
authors.initials: J
authors.lastname: Li
authors.forename: Xin
authors.initials: X
authors.lastname: Wang
authors.forename: Xi
authors.initials: X
authors.lastname: Yi
authors.forename: Limin
authors.initials: L
authors.lastname: Zhang
authors.forename: Zhongxing
authors.initials: Z
authors.lastname: Zhou
authors.forename: Huijuan
authors.initials: H
authors.lastname: Zhao
authors.forename: Feng
authors.initials: F
authors.lastname: Gao
mesh_terms: D000818:Animals; D004867:Equipment Design; D019544:Equipment Failure Analysis; D006863:Hydrogen-Ion Concentration; D007090:Image Interpretation, Computer-Assisted / Q000379:methods*; D008856:Microscopy, Fluorescence / Q000295:instrumentation*; D019047:Phantoms, Imaging; D010783:Photometry / Q000295:instrumentation*; D017785:Photons; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D041622:Tomography, Optical / Q000295:instrumentation*