Hemodynamic variability is detrimental in estimating the effective temporal resolution in a task-based fMRI - a phantom study

Motivation: With ultra-high-field MRI and acceleration methods, it is feasible to acquire a whole-brain image in a sub-second time. Nevertheless, the impact of neurovascular and physiological variability on the fMRI's effective temporal resolution (ETR) is not very clear. Goal(s): Our goal was to characterize the ETR in a task-based fMRI in case of varying hemodynamic responses and physiological fluctuations. Approach: Using a dynamic phantom, we generated different signal responses and evaluated ETR across the resulting dataset. Results: The ETR was prolonged by a factor of ~1.6 in case of varying hemodynamic responses and physiological fluctuations. Impact: This work shows a new tool to investigate the attainable effective temporal resolution of a particular fMRI experiment, demonstrating the effect of the variability in the fMRI response due to neurovascular and physiological variability.