Accelerated Human Cardiac Diffusion Tensor Imaging Using Simultaneous Multislice Imaging

PurposeTo demonstrate the feasibility of accelerating measurements of cardiac fiber structure using simultaneous multislice (SMS) imaging. MethodsSMS excitation with a blipped controlled aliasing (CAIPI) readout was incorporated into a diffusion-encoded stimulated echo pulse sequence to obtain diffusion measurements in three separate slices of the heart (8-mm thickness, 12-mm gap). A novel image entropy-based method for removing image ghosts in blipped CAIPI acquisitions is also introduced that enables SMS imaging of closely spaced slices in the heart. ResultsThe average retained signal-to-noise ratio (SNR) using this acquisition scheme is 70%5%, higher than the standard 1/3=57% SNR penalty with three-fold acceleration. No significant difference was observed in the apparent diffusion coefficient and helix angle diffusion parameters between a time-equivalent conventional single-slice scan and the three-fold accelerated SMS acquisition. A 10% mean bias was observed in fractional anisotropy between single-slice and SMS acquisitions. ConclusionThe new sequence was used to obtain high-quality diffusion measurements in three closely spaced cardiac slices in a clinically feasible nine breath-hold examination. The accelerated multiband sequence is anticipated to improve quantitative measurements of cardiac microstructure by reducing the number of breath-holds required for the scan, making it practical to incorporate diffusion tensor measurements within a comprehensive clinical examination. Magn Reson Med 73:995-1004, 2015. (c) 2014 Wiley Periodicals, Inc.