title: Modified multiscale sample entropy computation of laser speckle contrast images and comparison with the original multiscale entropy algorithm.
abstract: Laser speckle contrast imaging (LSCI) enables a noninvasive monitoring of microvascular perfusion. Some studies have proposed to extract information from LSCI data through their multiscale entropy (MSE). However, for reaching a large range of scales, the original MSE algorithm may require long recordings for reliability. Recently, a novel approach to compute MSE with shorter data sets has been proposed: the short-time MSE (sMSE). Our goal is to apply, for the first time, the sMSE algorithm in LSCI data and to compare results with those given by the original MSE. Moreover, we apply the original MSE algorithm on data of different lengths and compare results with those given by longer recordings. For this purpose, synthetic signals and 192 LSCI regions of interest (ROIs) of different sizes are processed. Our results show that the sMSE algorithm is valid to compute the MSE of LSCI data. Moreover, with time series shorter than those initially proposed, the sMSE and original MSE algorithms give results with no statistical difference from those of the original MSE algorithm with longer data sets. The minimal acceptable length depends on the ROI size. Comparisons of MSE from healthy and pathological subjects can be performed with shorter data sets than those proposed until now.
authors.affiliation: University of Angers, LARIS-Laboratoire Angevin de Recherche en Ingénierie des Systèmes, 62 avenue Notre-Dame du Lac, 49000 Angers, France.
authors.forename: Anne
authors.initials: A
authors.lastname: Humeau-Heurtier
authors.affiliation: Pôle imagerie médicale et explorations fonctionnelles, Hospital Pontchaillou of Rennes, University of Rennes 1, 35033 Rennes Cedex 9, FrancecInserm CIC 1414, 35033 Rennes cedex 9, France.
authors.forename: Guillaume
authors.initials: G
authors.lastname: Mahé
authors.affiliation: University of Angers, Hospital of Angers, Laboratoire de Physiologie et d Explorations Vasculaires UMR CNRS 6214-INSERM 1083, 49033 Angers cedex 01, France.
authors.forename: Pierre
authors.initials: P
authors.lastname: Abraham
mesh_terms: D000465:Algorithms; D001158:Arteries / Q000502:physiology*; D001783:Blood Flow Velocity / Q000502:physiology*; D019277:Entropy; D006801:Humans; D007089:Image Enhancement / Q000379:methods; D007090:Image Interpretation, Computer-Assisted / Q000379:methods*; D007834:Lasers; D061848:Optical Imaging / Q000379:methods*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity