Figure~\ref{548938} shows the gradient scheme. Saturation gradients had a time integral (length x strength) of Gt$_{sat} = $ 5.1 ms x 6.25 mT/m, the crusher gradients in read and slice direction of  Gt$_{cru} = $ 1.3 ms x 25 mT/m, the slice rephase gradient of Gt$_{sr} = $ 0.65 ms x 25 mT/m, the slice termination gradient of Gt$_{st} = $ 0.65 ms x 15 mT/m, and the total read dephase after EPI readout gradient of Gt$_{rt} =$ 0.65 ms x 22.5 mT/m. The angle between magnet field and gradient field was then 
\begin{eqnarray*}\begin{array}{l}\varphi_{cor}=\varphi-\tan^{-1}\left[\frac{\textnormal{Gt}_{cru}-\textnormal{Gt}_{rt}}{2 \textnormal{Gt}_{sat}+\textnormal{Gt}_{cru}+\textnormal{Gt}_{st}}\right]=\varphi-\textnormal{9.6}^\circ\end{array}\end{eqnarray*}
where $\varphi $ is the slice angulation. The imaging slice was set coronal above the ventricle. In addition, two saturation slices of 5 mm (15mm above and 20mm below) in thickness were placed parallel to the imaged slice. The following alternation (each with 1000 repetitions in five participants) were carried out, (a) slice angulation starting from coronal 0$^\circ$ to axial 90$^\circ $in the steps as [0, 10, 20, 30, 40, 45, 50, 55, 60, 65, 70, 80, 90], (b) the distance of the REST slabs were varied between 0.8 mm and 50 mm to alter the off-resonance frequency. The off-resonance frequencies were [2.62, 3.49, 4.36, 5.23, 6.11, 6.98, 7.84, 8.73, 9.60, 10.47, 12.22, 13.96, 15.71, 17.45] kHz, (c) Flip angle was varied for the case with saturation pulses from 5$^\circ $ to 60$^\circ $ in steps of 5$^\circ $(60$^\circ $was the power limit by the specific absorption rate (SAR)) and without saturation pulses from 5$^\circ $to 90$^\circ$ in steps of 5$^\circ$, (d) 9 slices were acquired at different positions, with each slice matching from bottom to the top the position of those acquired in the anatomical scan. In four participants, we examined the motion sensitivity where we immobilized the head with multiple cushions. During indicated intervals the subjects were asked to stop breathing for 20 s or to hyperventilate for 40 s. Finally, anatomical MRI images in all studies included a high-resolution sagittal, T1-weighted MP-RAGE (TR = 2.1 s, TE = 3.93 ms, flip angle = 7).\mbox{}\protect\newline Data were processed with Matlab 2014a (http://www.mathworks.co.uk/). Rescaling was applied to all data sets before any analysis using the MR vendor's instructions. Average time series were visually inspected in search for irregularities which were manually removed from the analysis leaving the rest of the time series unaltered. Manual segmentation was used to create a mask to remove cerebral spinal fluid (CSF) contributions. The first 100 scans were removed to avoid signal saturation effects. The manual segmentation of the masks was eroded to avoid partial volume effects at the edges. The cardiac signal and baseline detection was based on the method proposed in Gomes and Pereira\unskip~\cite{225062:5042988}.  Final data presentation was carried with Mathematica (Wolfram Research, Champaign, Illinois). 
       
\section*
  {Authors' contributions}
D.L.P. and C.K. performed initial experiments, D.L.P. performed validation experiments and analyzed the data, C.K. designed the research and wrote the paper.
\section*{Acknowledgments}We would like to thank S. Joseph for carrying out the imaging protocols for our participants, R. Fallon for reading the manuscript, and Science Foundation Ireland for supporting D.L.P. from 2011-2015 (SFI-11/RFP.1/NES/3051).