Abstract
To describe transverse relaxation of water in fixed tissue, we propose a model of transverse relaxation accelerated by diffusion and exchange (TRADE) that assumes exchange between free (visible) and bound (invisible) water, which relax by the dipole–dipole interaction, chemical exchange, and translation in the field gradient. Depending on the prevailing mechanism, transverse relaxation time (T2) of water in fixed tissue could increase (when dipole–dipole interaction prevails) or decrease with temperature (when diffusion in the field gradient prevails). Chemical exchange can make T2 even temperature independent. Also, variation of resolution from 100 to 15 μm/pxl (or less) affects effective transverse relaxation. T2 steadily decreases with increased resolution ((Formula presented.), (Formula presented.) is the read direction resolution). TRADE can describe all of these observations (semi)quantitatively. The model has been experimentally verified on water phantoms and on formalin-fixed zebrafish, mouse brain, and rabbit larynx tissues. TRADE could help predict optimal scanning parameters for high-resolution MRM from much faster measurements at lower resolution.
Original language | English (US) |
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Article number | e4747 |
Journal | NMR in Biomedicine |
Volume | 35 |
Issue number | 9 |
DOIs | |
State | Published - Sep 2022 |
Keywords
- MRM
- NMR
- T2W
- fixed tissue
- proton exchange
- resolution
- spin echo
- temperature
ASJC Scopus subject areas
- Molecular Medicine
- Radiology Nuclear Medicine and imaging
- Spectroscopy