Simulation of spatial and contrast distortions in keyhole imaging

Keyhole imaging is a scheme introduced to improve temporal resolution in dynamic contrast‐enhanced MRI by a factor of four or more. A “full” acquisition before contrast administration is followed by truncated acquisitions sensitive primarily to changes in image contrast. Simulations of the point‐spread functions that obtain, and their effect on contrast and spatial resolution, reveal significant degradation only for the smallest objects. Our simulations also address the feasibility of three‐dimensional keyhole imaging, and demonstrate a potential 16‐fold increase in temporal resolution. This suggests roles for keyhole imaging in conventional (nondynamic) precon‐trast and postcontrast studies and other applications.