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 Is-fold increase in temporal resolution: This suggests roles for keyhole imaging in conventional (nondynamic) precontrast and postcontrast studies and other applications.