Imaging the cerebral blood flow with enhanced laser speckle contrast analysis (eLASCA) by monotonic point transformation.

Abstract

Laser speckle contrast analysis (LASCA) has been demonstrated as a full-field method for imaging the cerebral blood flow (CBF). However, conventional LASCA is limited to extremely low dynamic range because of the ambient background field, dark current, and other anomalies in the circuits of a charge-coupled device camera, which makes it difficult to analyze the spatiotemporal variabilities in CBF. In this study, we proposed an enhanced LASCA (eLASCA) method to improve the dynamic range of LASCA based on monotonic point transformation. In investigating the influence of moderate hypothermia (32+/-0.5 degrees C) on capillary CBF change, eLASCA presented much more significant decrease of relative CBF than LASCA (hypothermia: 189% versus 137%, postrewarming: 151% versus 119%). Statistically, eLASCA resulted in a higher confidence degree (p=0.009) of CBF change after the rewarming than LASCA (p=0.013). In addition, eLASCA greatly improves the CBF visualization, which is very helpful in demonstrating the details of CBF change.