We evaluate residual aliasing among simultaneously excited and acquired slices in slice accelerated multiband (MB) echo planar imaging (EPI). No in-plane accelerations were used in order to maximize and evaluate achievable slice acceleration factors at 3. T. We propose a novel leakage (L-) factor to quantify the effects of signal leakage between simultaneously acquired slices. With a standard 32-channel receiver coil at 3. T, we demonstrate that slice acceleration factors of up to eight (MB = 8) with blipped controlled aliasing in parallel imaging (CAIPI), in the absence of in-plane accelerations, can be used routinely with acceptable image quality and integrity for whole brain imaging. Spectral analyses of single-shot fMRI time series demonstrate that temporal fluctuations due to both neuronal and physiological sources were distinguishable and comparable up to slice-acceleration factors of nine (MB = 9). The increased temporal efficiency could be employed to achieve, within a given acquisition period, higher spatial resolution, increased fMRI statistical power, multiple TEs, faster sampling of temporal events in a resting state fMRI time series, increased sampling of q-space in diffusion imaging, or more quiet time during a scan.
Bibliographical noteFunding Information:
We appreciate the helpful discussions with Kawin Setsompop (Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital). We would also like to thank Dingxin Wang, Keith Heberlein, Thomas Benner, Michael Hamm, and Franz Schmitt (Siemens Healthcare Solutions) for their technical input to the Human Connectome Skyra scanner. This project was supported in part by the Human Connectome Project ( U54MH091657-01 ) from the 16 National Institutes of Health (NIH) Institutes and Centers that support the NIH Blueprint for Neuroscience research, the National Center for Research Resources ( P41 RR008079 ), the National Institute of Biomedical Imaging and Bioengineering ( P41 EB015894 ), as well as by the NIH R44 NS073417 , P30 NS057091 and P30 NS076408 .
- Blipped CAIPI
- Leakage (L-) factor
- Residual aliasing
- Single-shot fMRI time series
- Spectral analysis