Exploration of movement artefacts in handheld laser speckle contrast perfusion imaging.

Functional performance of handheld laser speckle contrast imaging (LSCI) is compromised by movement artefacts. Here we quantify the movements of a handheld LSCI system employing electromagnetic (EM) tracking and measure the applied translational, tilt and on-surface laser beam speeds. By observing speckle contrast on static objects, the magnitudes of translation and tilt of wavefronts are explored for various scattering levels of the objects. We conclude that for tissue mimicking static phantoms, on-surface speeds play a dominant role to wavefront tilt speed in creation of movement artefacts. The ratio depends on the optical properties of the phantom. Furthermore, with the same applied speed, the drop in the speckle contrast increases with decreasing reduced scattering coefficient, and hence the related movement artefact increases.