Radiofrequency pulses for simultaneous short T2 excitation and long T2 suppression.

Magnetic resonance imaging of short T(2) musculoskeletal tissues such as ligaments, tendon, and cortical bone often requires specialized pulse sequences to detect sufficiently high levels of signal, as well as additional techniques to suppress unwanted long T(2) signals. We describe a specialized radiofrequency technique for imaging short T(2) tissues based on applying hard 180° radiofrequency excitation pulses to achieve simultaneous short T(2) tissue excitation and long T(2) tissue signal suppression for three-dimensional ultrashort echo time applications. A criterion for the pulse duration of the 180° radiofrequency pulses is derived that allows simultaneous water and fat suppression. This opens up possibilities for direct imaging of short T(2) tissues, without the need for additional suppression techniques. Bloch simulations and experimental studies on short T(2) phantoms and specimen were used to test the sequence performance.