Choice of numerical implementation of spatial contrast calculation impacts microcirculation quantitation in laser speckle contrast imaging

Numerical methods used to calculate <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mrow><mml:msub><mml:mi>K</mml:mi> <mml:mi>s</mml:mi></mml:msub> </mml:mrow> </mml:math> should be precisely acknowledged and validated against direct calculation to ensure accuracy. <i>Uniform</i> filter approach leads to accurate <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mrow><mml:msub><mml:mi>K</mml:mi> <mml:mi>s</mml:mi></mml:msub> </mml:mrow> </mml:math> values and is 100 times more computationally efficient than the <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:mi>D</mml:mi> <mml:mi>i</mml:mi> <mml:mi>r</mml:mi> <mml:mi>e</mml:mi> <mml:mi>c</mml:mi> <mml:mi>t</mml:mi></mml:mrow> </mml:math> calculation. Other investigated methods lead to various levels of errors in flow index estimation using LSCI. Errors are minimized using larger kernels. MESI derivation of <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mrow><mml:msub><mml:mi>τ</mml:mi> <mml:mi>c</mml:mi></mml:msub> </mml:mrow> </mml:math> is not immune but less affected by such methodological biases.