Montreal Neurological Institute coordinates of seed regions used in the functional connectivity analysis.

<p>Montreal Neurological Institute coordinates of seed regions used in the functional connectivity analysis.</p

Quantitative results.

<p>Mean correlation in overlapping significant voxels (Top), mean correlation in significant voxels for the E2, MEC, MECDN, and PW data separately (Middle), and network size, displayed as a fraction of intracranial voxels (Bottom). Voxels with P < 0.005 and minimum cluster size = 46, α = 0.05 were considered significant. Parameters were extracted on an individual subject basis. * = P < 0.05; ** = P < 0.01; *** = P < 0.001, Bonferroni-corrected.</p

MBME ASL/BOLD pulse sequence design.

<p>The sequence consists of a pCASL labeling train, followed by a post-label delay, and a multi-echo EPI readout. The phase is rewound to the start of k-space after each echo and the next echo is acquired. Multiband imaging was also utilized by inserting a multiband excitation pulse in place of the single band pulse. Finally, blipped-CAIPI was employed to reduce g-factor penalties associated with MB imaging.</p

Group seed-based functional connectivity maps.

<p>Connectivity maps are displayed for PCC, L/R motor cortex, L/R insula, and L/R hippocampus seeds. Maps are the result of a one-sample t-test on the Fisher-transformed z-scores and were thresholded at P < 0.005 with minimum cluster size = 46, α = 0.05. For all seed regions, connectivity was markedly increased in terms of network size and correlation strength for the MECDN datasets compared to the others. Limited insula and hippocampus connectivity was observed for the E2 and PW datasets. Bilateral insular connectivity was seen for the MEC dataset. The MECDN data produced significant bilateral connectivity with long-range connections for both the insula and hippocampus seeds. Robust connectivity was detected with the PW data for the PCC and motor network seeds. Some bilateral connectivity was seen for the insula seeds.</p

Group dual-regression based functional connectivity maps.

<p>Connectivity maps are displayed for the default mode network, motor network, and salience network. Maps are the result of a one-sample t-test on the z-scores and were thresholded at P < 0.005 with minimum cluster size = 46, α = 0.05. Additional clusters were seen for the MEC data compared to the E2 data and for all networks, and for the MECDN data compared to the MEC data for the DMN and salience networks. Existing clusters also tended to be larger for the MECDN data for these networks. Motor network connectivity was similar between the MEC and MECDN datasets. Bilateral, long range connectivity was seen for all datasets, including the PW data.</p

MEICA performance.

<p>MEICA performance.</p

Schematic showing the resting state functional connectivity pipeline for the ASL and BOLD echoes.

<p>The first and second echoes were processed separately to yield the PW and E2 data respectively. Echoes were also combined using a T2*-weighted approach to generate the MEC dataset. This dataset was further denoised using ME-ICA resulting in the MECDN dataset. Each echo was despiked, volume registered using the transformation matrix from the first echo, detrended, registered to the anatomical image, and transformed to MNI space. Additional preprocessing steps differ for each dataset and are shown in Row 2. For all datasets, after preprocessing, functional connectivity was assessed with seed-based and dual-regression approaches (Row 3).</p

Group CBF/BOLD coupling.

<p>Results are shown for the E2, MEC and MECDN datasets. Widespread coupling was observed and increased coupling was seen within well-known brain networks including the DMN, and visual networks. Stronger, more widespread coupling was seen for the MECDN data compared to the MEC and E2 data.</p