Short T-2 imaging using a 3D double adiabatic inversion recovery prepared ultrashort echo time cones (3D DIR-UTE-Cones) sequence

Purpose: To investigate high contrast imaging of short T-2 tissues with a three-dimensional double adiabatic inversion recovery prepared ultrashort echo time Cones (3D DIR-UTE-Cones) sequence. Methods: The sequence used two sequential adiabatic inversion pulses to suppress signals from long T-2 tissues, followed by multispoke UTE acquisition to detect signals from short T-2 tissues. The two adiabatic inversion pulses are identical with a center frequency located at the water peak, but the spectral width is broad enough to cover both water and fat frequencies. The feasibility of this technique was demonstrated through numerical simulation and phantom studies. Finally, DIR-UTE-Cones was applied to three healthy volunteers to image cortical bone, patellar tendon, and Achilles tendon. T*(2) was also measured via single-component exponential fitting. Results: Numerical simulation suggests that the DIR technique provides perfect nulling of muscle and fat as well as efficient suppression of other long T-2 tissues with T-1 values between fat and water or those above water. Excellent image contrast can be achieved with DIR-UTE-Cones for the short T-2 tissues, with fitted T*(2) values of 0.28-0.38 ms for cortical bone, 0.56 +/- 0.07 ms for the patella tendon, and 0.45 +/- 0.06 ms for the Achilles tendon, respectively. Conclusion: The 3D DIR-UTE-Cones sequence provides robust suppression of long T-2 tissues and allows selective imaging as well as T*(2) measurement of short T-2 tissues such as cortical bone, patellar tendon, and the Achilles tendon. (C) 2017 International Society for Magnetic Resonance in Medicine.