Analyzing the sensitivity of quantitative 3D MRI of longitudinal relaxation at very low field in Gd-doped phantoms

Danilo de Iure; Allegra Conti; Angelo Galante; Sara Spadone; Ingo Hilschenz; Massimo Caulo; Stefano Sensi; Cosimo Del Gratta; Stefania Della Penna

doi:10.1371/journal.pone.0285391

Analyzing the sensitivity of quantitative 3D MRI of longitudinal relaxation at very low field in Gd-doped phantoms

PLoS One. 2023 May 5;18(5):e0285391. doi: 10.1371/journal.pone.0285391. eCollection 2023.

Authors

Danilo de Iure¹, Allegra Conti^{1

2}, Angelo Galante^{3

4

5}, Sara Spadone¹, Ingo Hilschenz¹, Massimo Caulo^{1

6}, Stefano Sensi^{1

6}, Cosimo Del Gratta^{1

6}, Stefania Della Penna^{1

6}

Affiliations

¹ Department of Neuroscience, Imaging and Clinical Sciences, G. D'Annunzio University of Chieti and Pescara, Chieti, CH, Italy.
² Medical Physics Section, Department of Biomedicine and Prevention, University of Rome Tor Vergata, Rome, Italy.
³ MESVA, Department of Life, Health & Environmental Sciences, L'Aquila University, L'Aquila, AQ, Italy.
⁴ INFN, National Institute of Nuclear Physics, Gran Sasso National Laboratories, Assergi, L'Aquila, Italy.
⁵ CNR, SPIN-CNR Institute, Dept. of Physical and Chemical Sciences, L'Aquila, Italy.
⁶ Institute for Advanced Biomedical Technologies (ITAB), G. D'Annunzio University of Chieti and Pescara, Chieti, CH, Italy.

Abstract

Purpose: Recently, new MRI systems working at magnetic field below 10 mT (Very and Ultra Low Field regime) have been developed, showing improved T1-contrast in projected 2D maps (i.e. images without slice selection). Moving from projected 2D to 3D maps is not trivial due to the low SNR of such devices. This work aimed to demonstrate the ability and the sensitivity of a VLF-MRI scanner operating at 8.9 mT in quantitatively obtaining 3D longitudinal relaxation rate (R1) maps and distinguishing between voxels intensities. We used phantoms consisting of vessels doped with different Gadolinium (Gd)-based Contrast Agent (CA) concentrations, providing a set of various R1 values. As CA, we used a commercial compound (MultiHance®, gadobenate dimeglumine) routinely used in clinical MRI.

Methods: 3D R1 maps and T1-weighted MR images were analysed to identify each vessel. R1 maps were further processed by an automatic clustering analysis to evaluate the sensitivity at the single-voxel level. Results obtained at 8.9 mT were compared with commercial scanners operating at 0.2 T, 1.5 T, and 3 T.

Results: VLF R1 maps offered a higher sensitivity in distinguishing the different CA concentrations and an improved contrast compared to higher fields. Moreover, the high sensitivity of 3D quantitative VLF-MRI allowed an effective clustering of the 3D map values, assessing their reliability at the single voxel level. Conversely, in all fields, T1-weighted images were less reliable, even at higher CA concentrations.

Conclusion: In summary, with few excitations and an isotropic voxel size of 3 mm, VLF-MRI 3D quantitative mapping showed a sensitivity better than 2.7 s-1 corresponding to a concentration difference of 0.17 mM of MultiHance in copper sulfate doped water, and improved contrast compared to higher fields. Based on these results, future studies should characterize R1 contrast at VLF, also with other CA, in the living tissues.

Copyright: © 2023 de Iure et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.

Publication types

Research Support, Non-U.S. Gov't

MeSH terms

Contrast Media
Magnetic Resonance Imaging* / methods
Organometallic Compounds*
Reproducibility of Results

Substances

gadobenic acid
Organometallic Compounds
Contrast Media

Grants and funding

For S.D.P., S.Sp., I.H. and C.D.G.: This work was carried out under the OXiNEMS project (www.oxinems.eu), funded by the European Union's Horizon 2020 research and innovation program under Grant Agreement No. 828784. For S.D.P., C.D.G., S.Se. This work was also supported by the "Departments of Excellence 2018–2022", MIUR, for the Department of Neuroscience, Imaging and Clinical Sciences, University of Chieti-Pescara. D.d.I. was funded by the project: PON RICERCA e INNOVAZIONE 2014-2020, Dottorati innovativi a caratterizzazione industriale A.A. 2017-2018 - DOT1353282. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.