UC San Diego

Purpose

To investigate high contrast imaging of short T₂ 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 T₂ tissues, followed by multispoke UTE acquisition to detect signals from short T₂ 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. T2* 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 T₂ tissues with T₁ values between fat and water or those above water. Excellent image contrast can be achieved with DIR-UTE-Cones for the short T₂ tissues, with fitted T2* 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 T₂ tissues and allows selective imaging as well as T2* measurement of short T₂ tissues such as cortical bone, patellar tendon, and the Achilles tendon. Magn Reson Med 79:2555-2563, 2018. © 2017 International Society for Magnetic Resonance in Medicine.