A diffusion-based method for long-T2 suppression in steady state sequences: Validation and application for 3D-UTE imaging.

PURPOSE: To introduce a novel method for long-T2 signal physical suppression in steady-state based on configuration states combination and modulation using diffusion weighting. Its efficiency in yielding a high contrast in short-T2 structures using an ultrashort echo time acquisition module (Diff-UTE) is compared to the adiabatically prepared Inversion-Recovery-UTE sequence (IR-UTE). THEORY AND METHODS: Using a rectangular-pulse prepared 3D-UTE sequence, the possibility of long-T2 component signal cancellation through diffusion effects is addressed, and the condition met for sets of sequence parameters. Simultaneously, the short-T2 component signal is maximized using a Bloch equation-based optimization process. The method is evaluated from simulations, and experiments are conducted on a phantom composed of short and long-T2 components, as well as on an ex vivo mouse head. RESULTS: Within equal scan times, the proposed method allowed for an efficient long-T2 signal suppression, and expectedly yielded a higher signal to noise ratio in short-T2 structures compared to the IR-UTE technique, although an intrinsic short-T2 signal loss is expected through the preparation module. CONCLUSION: The Diff-UTE method represents an interesting alternative to the IR-UTE technique. Diffusion weighting allowing for a long-T2 suppression results in a less penalizing method to generate a high and selective contrast in short-T2 components. Magn Reson Med 80:548-559, 2018. © 2017 International Society for Magnetic Resonance in Medicine.