Comparison of optimized soft‐tissue suppression schemes for ultrashort echo time MRI

Ultrashort echo time (UTE) imaging with soft‐tissue suppression reveals short‐ T 2 components (typically hundreds of microseconds to milliseconds) ordinarily not captured or obscured by long‐ T 2 tissue signals on the order of tens of milliseconds or longer. Therefore, the technique enables visualization and quantification of short‐ T 2 proton signals such as those in highly collagenated connective tissues. This work compares the performance of the three most commonly used long‐ T 2 suppression UTE sequences, i.e., echo subtraction (dual‐echo UTE), saturation via dual‐band saturation pulses (dual‐band UTE), and inversion by adiabatic inversion pulses (IR‐UTE) at 3 T, via Bloch simulations and experimentally in vivo in the lower extremities of test subjects. For unbiased performance comparison, the acquisition parameters are optimized individually for each sequence to maximize short‐ T 2 signal‐to‐noise ratio (SNR) and contrast‐to‐noise ratio (CNR) between short‐ and long‐ T 2 components. Results show excellent short‐ T 2 contrast which is achieved with these optimized sequences. A combination of dual‐band UTE with dual‐echo UTE provides good short‐ T 2 SNR and CNR with less sensitivity to B 1 homogeneity. IR‐UTE has the lowest short‐ T 2 SNR efficiency but provides highly uniform short‐ T 2 contrast and is well suited for imaging short‐ T 2 species with relatively short T 1 such as bone water. Magn Reson Med, 2012. © 2011 Wiley Periodicals, Inc.