Comparison of automated and manual intracellular particle tracking using quantitative phase imaging

Transport within cells is commonly studied using particle tracking methods. However, these typically require either labeling or identification of specific organelles that can be identified and tracked from label-free imaging modalities, limiting application of this approach. Quantitative phase imaging (QPI) provides dynamic data on the redistribution of mass within live cells, potentially enabling broader application of particle tracking methods. In previous work, we developed quantitative phase velocimetry (QPV) to automatically track the motion of subcellular control volumes from QPI data. However, the relationship of QPV to traditional particle tracking methods has not been established. Here, we directly compare QPV to manual particle tracking across multiple drug treatment conditions. We find that QPV effective diffusivity is correlated with diffusivity measured from manual particle tracking. The differences between QPV and manual tracking are explained by the difference in effective size of particles tracked by QPV. Overall, these data indicate that automated tracking of the motion of cellular mass from QPI data can effectively be used to characterize effective diffusivity within living cells.