real-time fMRI

real-time fMRI optimizes BOLD sensitivity by evaluating and combining multi-echo fMRI time series to improve offline and real-time functional contrast measurements.

Key Features:

• Multi-Echo Data Combination: Evaluates six approaches: a single-echo time series based on Echo 2, a real-time T2*-mapped time series (T2*FIT), and four combined time series—T2*-weighted, tSNR-weighted, TE-weighted, and a novel T2*FIT-weighted combination.
• BOLD Sensitivity Enhancement: Demonstrates that the T2*FIT-weighted combination yields the largest increase in temporal signal-to-noise ratio (tSNR) across task-based and resting-state runs in a cohort of 28 healthy volunteers.
• Real-Time Analysis: Improves region-of-interest real-time functional contrasts using the T2*FIT time series, which shows the largest offline effect size measures across evaluated tasks.
• Methodological Rigor: Recommends continued exploration and use of T2*FIT for offline task-based and real-time fMRI analyses while noting an observed decrease in tSNR for the standalone T2*FIT time series.

Scientific Applications:

• Real-time fMRI paradigms: Supports rapid detection and combination of multi-echo BOLD signals for online functional contrast estimation.
• Neurofeedback: Enables enhanced BOLD sensitivity and rapid feedback signals for neurofeedback experiments.
• Brain-computer interfaces: Applicable to BCIs requiring fast and sensitive detection of neural activity from fMRI signals.

Methodology:

Performs systematic comparisons of six multi-echo combination methods (Echo 2, T2*FIT, T2*-weighted, tSNR-weighted, TE-weighted, T2*FIT-weighted), computes temporal signal-to-noise ratio (tSNR) and offline effect size measures, and evaluates region-of-interest real-time functional contrasts using task-based and resting-state fMRI data from 28 healthy volunteers.