Unraveling the major role of vascular ( R2 ') contributions to R2 signal relaxation at ultra‐high‐field MRI : A comprehensive analysis with quantitative gradient recalled echo in mouse brain
Ultra-high-field (UHF) R2* relaxometry is often used for in vivo analysis of biological tissue microstructure without accounting for vascular contributions to R2* signal, that is, the BOLD signal component, and magnetic field inhomogeneities. These effects are especially important at UHF as their co...
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Published in | Magnetic resonance in medicine Vol. 94; no. 2; pp. 761 - 770 |
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Main Authors | , , , , , , , |
Format | Journal Article |
Language | English |
Published |
United States
Wiley Subscription Services, Inc
01.08.2025
John Wiley and Sons Inc |
Subjects | |
Online Access | Get full text |
ISSN | 0740-3194 1522-2594 1522-2594 |
DOI | 10.1002/mrm.30529 |
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Summary: | Ultra-high-field (UHF) R2* relaxometry is often used for in vivo analysis of biological tissue microstructure without accounting for vascular contributions to R2* signal, that is, the BOLD signal component, and magnetic field inhomogeneities. These effects are especially important at UHF as their contribution to R2* scales linearly with magnetic field. Our study aims to report on the results of separate contributions of R2t* (tissue-specific sub-component) and R2' (vascular BOLD sub-component), corrected for the adverse effects of magnetic field inhomogeneities, to the total R2* signal at in vivo UHF MRI of mouse brain.
Four healthy, 8-week-old C57BL/6J mice were imaged in vivo with multi-gradient echo MRI at 9.4 T and analyzed using the quantitative gradient recalled echo (qGRE) approach. A segmentation protocol was established using the Dorr Mouse Brain Atlas and ANTs Syn registration to warp template brain region labels to subject qGRE maps.
By separating R2' contribution from R2* signal, we have established normative R2t* data in mouse brain. Our findings revealed significant contributions of R2' to R2*, with approximately 42% of the R2* signal arising from vascular contributions, thus suggesting the R2t* as a more accurate metric for quantifying tissue microstructural information and its changes in neurodegenerative diseases.
qGRE approach allows efficient separation of tissue microstructure-specific (R2t*), vascular BOLD (R2'), and background gradients contributions to the total R2* relaxation at UHF MRI. Due to low concentration of non-heme iron in mouse brain, major contribution to R2t* results from tissue cellular components. |
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Bibliography: | ObjectType-Article-1 SourceType-Scholarly Journals-1 ObjectType-Feature-2 content type line 14 content type line 23 |
ISSN: | 0740-3194 1522-2594 1522-2594 |
DOI: | 10.1002/mrm.30529 |