Functional imaging with MR T1 contrast: a feasibility study with blood-pool contrast agent

Area of Science:

• Neuroimaging
• Medical Imaging
• Functional MRI

Background:

• Traditional functional magnetic resonance imaging (fMRI) relies on the blood oxygenation level-dependent (BOLD) effect, which can be prone to signal dropouts and artifacts.
• Cerebral blood volume (CBV) imaging offers an alternative contrast mechanism that may be less susceptible to these limitations.

Purpose of the Study:

• To demonstrate the feasibility of using a long intravenous half-life blood-pool T1 contrast agent as a new functional imaging method.
• To compare the performance of a T1-sensitive gradient-echo (GRE) sequence for CBV imaging against a standard T2* echo-planar imaging (EPI) sequence for BOLD imaging during a motor task.

Main Methods:

• Ten healthy subjects underwent two dynamic magnetic resonance (MR) imaging protocols: a reference BOLD-EPI sequence and a T1-GRE sequence using a novel gadolinium-based CBV contrast agent.
• Both sequences were performed during a block-type finger-tapping paradigm.
• Statistical analysis was conducted using SPM5 software.

Main Results:

• Maximum activation in both BOLD and CBV imaging was localized to the left postcentral gyrus (peak Z-score = 5.5, cluster size 3,449 voxels).
• Signal amplitude for T1 CBV contrast was approximately 0.5%, compared to 1% for EPI BOLD.
• The T1-based CBV method demonstrated potential for reduced image artifacts.

Conclusions:

• A novel functional imaging method utilizing a long-acting T1 blood-pool contrast agent for CBV measurement has been proposed and verified.
• This T1-CBV approach offers a promising alternative to BOLD imaging, potentially yielding fewer artifacts.
• Further research is warranted to fully explore the clinical utility of this advanced neuroimaging technique.