Simulation of relative temporal resolution of time‐resolved MRA sequences

Abstract

Time-resolved MRA sequences are typically characterized by the display frame rate. However, true temporal resolution should be defined in a manner analogous to spatial resolution; it is not the ability of a sequence to update rapidly but rather the ability to discern changes that occur within a small time that should characterize temporal resolution. For view-shared methods like Keyhole and time-resolved imaging of contrast kinetics (TRICKS), regions of k-space from multiple time frames are combined to form a single reconstructed time frame. This often causes the time needed to acquire all k-space data points to be significantly longer than the displayed frame time, resulting in a poor frequency response. Simulated here are the temporal impulse response and temporal frequency response (TFR) curves of three time-resolved MRA methods, including the recently introduced highly-constrained backprojection local reconstruction (HYPR LR) method. It is found that the HYPR LR reconstruction method exhibits a better TFR for a larger spectrum of temporal and spatial frequencies than the Keyhole and TRICKS methods.