Multi-exposure speckle imaging through an optical fiber bundle.

Significance: Multi-exposure speckle imaging (MESI) is a label-free technique to visualize and measure blood flow. Accurate perfusion measurements are useful in a variety of applications, including surgery, monitoring treatment, and diagnosing various conditions. Aim: We aim to demonstrate the feasibility of capturing speckle images through an optical fiber bundle for use in MESI for potential applications such as endoscopy or where free space measurements are not feasible. Approach: To compare the accuracy of fiber bundle MESI measurements against free space MESI measurements, measurements of a tissue-simulating flow phantom and in vivo mouse cortex were acquired simultaneously through free space and an optical fiber bundle. Results: Using the Pearson correlation coefficient for comparing measurements, R 2 values of 0.9994 and 0.9942 were calculated for low (1 to 10    μ L / min ) and high (10 to 100    μ L / min ) flow rates, respectively. For in vivo measurements, an R 2 value of 0.970 was calculated for flow in 14 vessels and 5 parenchyma regions. R 2 values of 0.953 and 0.906 were calculated for two vessels before, during, and after a stroke. Conclusions: MESI measurements through an optical fiber bundle show similar results to free-space MESI.