1. A functional magnetic resonance scanner apparatus comprising at least one processor communicatively coupled with at least one non-transitory computer readable medium, wherein the processor is programmed to: obtain functional magnetic resonance imaging (“fMRI”) data based on blood oxygen level dependence (“BOLD”); convert the fMRI/BOLD data to hemodynamic response (“HDR”) data comprising a graph of the BOLD over time; analyze the HDR data to determine an abnormal HDR response by identifying a negative trough in the HDR data; identify a vascular drainage insufficiency in the central nervous system based on said abnormal HDR response.