Multiband multi-echo imaging of simultaneous oxygenation and flow timeseries for resting state connectivity

PLoS One. 2017 Mar 2;12(3):e0169253. doi: 10.1371/journal.pone.0169253. eCollection 2017.

Abstract

A novel sequence has been introduced that combines multiband imaging with a multi-echo acquisition for simultaneous high spatial resolution pseudo-continuous arterial spin labeling (ASL) and blood-oxygenation-level dependent (BOLD) echo-planar imaging (MBME ASL/BOLD). Resting-state connectivity in healthy adult subjects was assessed using this sequence. Four echoes were acquired with a multiband acceleration of four, in order to increase spatial resolution, shorten repetition time, and reduce slice-timing effects on the ASL signal. In addition, by acquiring four echoes, advanced multi-echo independent component analysis (ME-ICA) denoising could be employed to increase the signal-to-noise ratio (SNR) and BOLD sensitivity. Seed-based and dual-regression approaches were utilized to analyze functional connectivity. Cerebral blood flow (CBF) and BOLD coupling was also evaluated by correlating the perfusion-weighted timeseries with the BOLD timeseries. These metrics were compared between single echo (E2), multi-echo combined (MEC), multi-echo combined and denoised (MECDN), and perfusion-weighted (PW) timeseries. Temporal SNR increased for the MECDN data compared to the MEC and E2 data. Connectivity also increased, in terms of correlation strength and network size, for the MECDN compared to the MEC and E2 datasets. CBF and BOLD coupling was increased in major resting-state networks, and that correlation was strongest for the MECDN datasets. These results indicate our novel MBME ASL/BOLD sequence, which collects simultaneous high-resolution ASL/BOLD data, could be a powerful tool for detecting functional connectivity and dynamic neurovascular coupling during the resting state. The collection of more than two echoes facilitates the use of ME-ICA denoising to greatly improve the quality of resting state functional connectivity MRI.

MeSH terms

  • Adult
  • Brain / blood supply
  • Brain / metabolism
  • Brain Mapping
  • Cerebral Arteries / physiology
  • Cerebrovascular Circulation*
  • Echo-Planar Imaging*
  • Female
  • Humans
  • Magnetic Resonance Imaging*
  • Male
  • Middle Aged
  • Nerve Net / blood supply*
  • Nerve Net / metabolism*
  • Oxygen / blood
  • Oxygen / metabolism*
  • Rest / physiology*
  • Time Factors
  • Young Adult

Substances

  • Oxygen

Grants and funding

This work was partially supported by a grant from the Daniel M. Soref Charitable Trust (to Yang Wang). Author R. Marc Lebel is employed by GE Healthcare. The funder provided support in the form of salary for author RML, but did not have any additional role in the study design, data collection and analysis, decision to publish, or preparation of the manuscript. The specific roles of this author are articulated in the ‘author contributions’ section.