# Toward robust whole-brain 3D functional MRI at 3T with reduced signal loss artifacts

> **NIH NIH R21** · UNIVERSITY OF MICHIGAN AT ANN ARBOR · 2020 · $185,924

## Abstract

ABSTRACT
T2*-weighted functional magnetic resonance imaging (fMRI) is used widely to investigate brain function, both at rest
and in response to a stimulus or task. Unfortunately, BOLD fMRI is susceptible to spatial signal variations due to
inhomogeneities in the static magnetic field (B0) that are unrelated to neuronal activity. This effect is pronounced near
air/tissue boundaries, where steep magnetic field gradients can cause the BOLD signal to vanish. As a result, the BOLD
signal is often partly or completely missing from the orbitofrontal cortex and ventromedial prefrontal cortex, believed to
be important for high-level cognitive tasks such as decision-making and adaptive learning. To address this problem,
we will develop a whole-brain 3D BOLD fMRI acquisition and reconstruction protocol with minimal signal loss artifacts
and improved temporal SNR. We propose a three-pronged approach to reducing signal loss in 3D BOLD fMRI: We
will (i) replace the conventional slab-selective radiofrequency (RF) excitation with a 3D spatially tailored RF pulse that
“pre-phases” the spins to make them refocus at a later time, (ii) perform model-based image reconstruction from parallel
imaging data that accounts for the remaining effects of susceptibility-induced through-voxel B0 gradients, and (iii) perform
z-shimming as needed to alleviate the pre-phasing demands placed on the RF pulse. We will also employ a more efficient
radiofrequency (RF) spoiling scheme that enables reduced spoiler gradients. We hypothesize that the proposed protocol
will achieve more complete spatial coverage than 2D fMRI, and more complete assessment of ventromedial prefrontal
cortex (vmPFC) activation in obsessive-compulsive disorder (OCD) patients. Our goal is that the proposed protocol will
serve as a broadly applicable “drop-in replacement” for existing BOLD fMRI sequences, and that it will enable novel
studies into the role of, e.g., the orbitofrontal cortex and ventromedial prefrontal cortex in resting-state and task-based
fMRI.

## Key facts

- **NIH application ID:** 9867618
- **Project number:** 5R21AG061839-02
- **Recipient organization:** UNIVERSITY OF MICHIGAN AT ANN ARBOR
- **Principal Investigator:** Jon-Fredrik Nielsen
- **Activity code:** R21 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2020
- **Award amount:** $185,924
- **Award type:** 5
- **Project period:** 2019-02-15 → 2023-01-31

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/9867618

## Citation

> US National Institutes of Health, RePORTER application 9867618, Toward robust whole-brain 3D functional MRI at 3T with reduced signal loss artifacts (5R21AG061839-02). Retrieved via AI Analytics 2026-05-25 from https://api.ai-analytics.org/grant/nih/9867618. Licensed CC0.

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