title: Extraction of diffuse correlation spectroscopy flow index by integration ofNth-order linear model with Monte Carlo simulation.
abstract: Conventional semi-infinite solution for extracting blood flow index (BFI) from diffuse correlation spectroscopy (DCS) measurements may cause errors in estimation of BFI (αDB) in tissues with small volume and large curvature. We proposed an algorithm integratingNth-order linear model of autocorrelation function with the Monte Carlo simulation of photon migrations in tissue for the extraction ofαDB. The volume and geometry of the measured tissue were incorporated in the Monte Carlo simulation, which overcome the semi-infinite restrictions. The algorithm was tested using computer simulations on four tissue models with varied volumes/geometries and applied on anin vivostroke model of mouse. Computer simulations shows that the high-order (N≥ 5) linear algorithm was more accurate in extractingαDB(errors < ±2%) from the noise-free DCS data than the semi-infinite solution (errors: -5.3% to -18.0%) for different tissue models. Although adding random noises to DCS data resulted inαDBvariations, the mean values of errors in extractingαDBwere similar to those reconstructed from the noise-free DCS data. In addition, the errors in extracting the relative changes ofαDBusing both linear algorithm and semi-infinite solution were fairly small (errors < ±2.0%) and did not rely on the tissue volume/geometry. The experimental results from thein vivostroke mice agreed with those in simulations, demonstrating the robustness of the linear algorithm. DCS with the high-order linear algorithm shows the potential for the inter-subject comparison and longitudinal monitoring of absolute BFI in a variety of tissues/organs with different volumes/geometries.
authors.affiliation: Department of Biomedical Engineering, University of Kentucky, Lexington, Kentucky 40506, USA.
authors.forename: Yu
authors.initials: Y
authors.lastname: Shang
authors.affiliation: Department of Biomedical Engineering, University of Kentucky, Lexington, Kentucky 40506, USA ; State Key Laboratory for Electronic Thin Film and Integrated Device, University of Electronic Science and Technology of China, Chengdu 610054, People's Republic of China.
authors.forename: Ting
authors.initials: T
authors.lastname: Li
authors.affiliation: Department of Neurosurgery, University of Kentucky, Lexington, Kentucky 40536, USA.
authors.forename: Lei
authors.initials: L
authors.lastname: Chen
authors.affiliation: Department of Biomedical Engineering, University of Kentucky, Lexington, Kentucky 40506, USA.
authors.forename: Yu
authors.initials: Y
authors.lastname: Lin
authors.affiliation: Department of Neurosurgery, University of Kentucky, Lexington, Kentucky 40536, USA.
authors.forename: Michal
authors.initials: M
authors.lastname: Toborek
authors.affiliation: Department of Biomedical Engineering, University of Kentucky, Lexington, Kentucky 40506, USA.
authors.forename: Guoqiang
authors.initials: G
authors.lastname: Yu