Second-level fixed-effects (FE) fMRI results - Differential contrast.

<p>(A) Revealing a cluster of significantly increased activation detected by k-space density weighted compared to conventional Cartesian EPI for left-hand finger tapping in n = 5 subjects (thresholded using clusters determined by Z>2.3 at a FWER-corrected p≤0.05 and displayed in MNI152 standard space). In the opposite, no areas of increased activation detected by Cartesian over density weighted EPI were found. (B) Time-courses within this cluster (extracted from raw data prior to further processing and averaged across n = 5 subjects) reveal increased percentual BOLD signal changes of density weighted compared to Cartesian EPI for each of the five blocks of the finger-tapping task.</p

Bland-Altman difference plots of quantitative parameter gains.

<p>Gains are plotted on a voxel-to-voxel basis for spatial SNR, temporal SNR and relative signal change (rSC; scaled to the mean Cartesian value) for density weighted (DW) over Cartesian (Cart) EPI in n = 5 subjects. Red solid lines represent the mean difference across voxels and subjects, red dashed lines ±1.96 × the standard deviation (SD; 95% limits of agreement for each comparison). The dotted gray line represents identity (no difference). Average increases in spatial SNR (12.4%, t = 15.68), temporal SNR (5.5%, t = 2.46) and rSC (8.6%, t = 2.63) were consistent and statistically significant (p<0.03125; based on mean within-subject differences). Gray data points and corresponding gray lines in the tSNR plot represent values of one additional subject measured at rest for comparison.</p

Corresponding local activation maxima from second level fixed-effects (FE) analyses of the mean activation evoked by left-hand finger tapping as detected by density weighted and Cartesian EPI in n = 5 subjects.

<p>R … right, SMA … supplementary motor area, G. … gyrus.</p><p>x, y, z …MNI152 coordinates [mm].</p><p>t-stats … statistical t-values.</p>*<p>based on the Havard-Oxford Cortical Structural Atlas (part of FSL).</p

Phantom images and corresponding spatial response functions.

<p>Images were reconstructed from k-space density weighted (A), Cartesian (B) and unfiltered Cartesian acquisition (C). Spatial response functions (D) were obtained from the edge spread functions indicated by the red bars.</p

First-level fMRI results.

<p>Five consecutive slices of the statistical activation images thresholded using clusters (determined by Z>2.3 and a FWER-corrected p≤0.05) of the subject presented in Fig. 4 for the density weighted and the Cartesian acquisition.</p

Representative slices of the brain of a healthy volunteer.

<p>Images are shown for k-space density weighted (A), Cartesian filtered (B), unfiltered density weighted (C) and unfiltered Cartesian reconstructions (D). Cartesian and density weighted images correspond well in geometry and contrast.</p

Second-level fixed-effects (FE) fMRI results - Mean activation.

<p>Evoked by left-hand finger tapping in n = 5 subjects as detected by density weighted (top) and Cartesian (bottom) EPI acquisitions (all thresholded using clusters determined by Z>2.3 at a FWER-corrected p≤0.05 and projected to the pial surface of the MNI152 template).</p

Cartesian (A) and density weighted acquisition (B) for a typical fMRI experiment.

<p>The MTF (bottom, grey) results from a multiplication of the k-space density <i>ρ(k)</i> (blue, top) with the signal <i>S(k)</i> (green) and the filter <i>f(k)</i> (red).</p