Harmonization of Multi-site Dynamic Functional Connectivity Network Data

Neuroscience studies have begun to benefit from combining large numbers of data from different sites to increase statistical power. Pooling data from various sites into a single analysis introduces additional variability from site-effects due to differences in scanner protocols, imaging protocol, and acquisition methods, among others. These site-effects can reduce statistical power or lead to erroneous conclusions. Harmonization is the process of combining data aiming at reducing site variability. One recent approach for harmonizing data called ComBat has been shown to be helpful in the context of functional MRI and static functional connectivity. However, ComBat has not been applied to the analysis of dynamic functional network connectivity (dFNC). Here we explore the impact of ComBat harmonization on dFNC data collected from two different mild traumatic brain injury (mTBI) studies. Results show that ComBat harmonization of dFNC can reduce site effects producing a more robust analysis of patient effects across sites.