Magnetic Resonance Imaging of Short T2 Relaxation Components in Tissue Using Ultrashort Echo Time (UTE) Pulse Sequences

摘要

The clinical use of ultrashort echo time (UTE) pulse sequences for imaging tissues or tissue relaxation components with short T2s is described. Tissues are divided into those with a majority of short T2 components and those with a minority. Disease processes which increase or decrease the signal from short T2 components are described. Features of the basic physics are described including the fact that when the radiofrequency pulse duration is of the order of T2, rotation of tissue magnetization less than the specified flip angle. The basic UTE pulse sequence with its half excitation pulses and radial imaging from the center of k-space is described together with options that suppress fat and/or long T2 components. Features of the imaging of cortical bone, tendons, ligaments, menisci and periosteum are illustrated. Possible future developments are outlined.