New functional MRI experiments based on fractional diffusion representation show independent and complementary contrast to diffusion-weighted and blood-oxygen-level-dependent functional MRI

Maiuro, Alessandra, Palombo, Marco ORCID: https://orcid.org/0000-0003-4892-7967, Macaluso, Emiliano, Genovese, Guglielmo, Bozzali, Marco, Giove, Federico and Capuani, Silvia 2025. New functional MRI experiments based on fractional diffusion representation show independent and complementary contrast to diffusion-weighted and blood-oxygen-level-dependent functional MRI. Applied Sciences 15 (9) , 4930. 10.3390/app15094930

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Abstract

A fundamental limitation of fMRI based on the BOLD effect is its limited spatial specificity. This is because the BOLD signal reflects neurovascular coupling, leading to macrovascular changes that are not strictly limited to areas of increased neural activity. However, neuronal activation also induces microstructural changes within the brain parenchyma by modifying the diffusion of extracellular biological water. Therefore, diffusion-weighted imaging (DWI) has been applied in fMRI to overcome BOLD limits and better explain the mechanisms of functional activation, but the results obtained so far are not clear. This is because a DWI signal depends on many experimental variables: instrumental, physiological, and microstructural. Here, we hypothesize that the γ parameter of the fractional diffusion representation could be of particular interest for DW-fMRI applications, due to its proven dependence on local magnetic susceptibility and diffusion multi-compartmentalization. BOLD fMRI and DW-fMRI experiments were performed at 3T using an exemplar application to task-based activation of the human visual cortex. The results, corroborated by simulation, highlight that γ provides complementary information to conventional diffusion fMRI and γ can quantify cellular morphology changes and neurovascular regulation during neuronal activation with higher sensitivity and specificity than conventional BOLD fMRI and DW-fMRI.

Item Type:	Article
Date Type:	Published Online
Status:	Published
Schools:	Schools > Psychology Research Institutes & Centres > Cardiff University Brain Research Imaging Centre (CUBRIC)
Additional Information:	License information from Publisher: LICENSE 1: URL: https://creativecommons.org/licenses/by/4.0/, Type: open-access
Publisher:	MDPI
Date of First Compliant Deposit:	14 May 2025
Date of Acceptance:	24 April 2025
Last Modified:	14 May 2025 10:15
URI:	https://orca.cardiff.ac.uk/id/eprint/178274

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