A theoretical framework for the assessment of water fraction-dependent longitudinal decay rates and magnetisation transfer in membrane lipid phantoms
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arXiv
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| Format: | Preprint |
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2024
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| author | Neeb, Heiko Schyboll, Felix Shaharabani, Rona Mezer, Aviv A. Shtangel, Oshrat |
| author_facet | Neeb, Heiko Schyboll, Felix Shaharabani, Rona Mezer, Aviv A. Shtangel, Oshrat |
| contents | Phantom systems consisting of liposome suspensions are widely employed to investigate quantitative MRI parameters mimicking cellular membranes. The proper physical understanding of the measurement results, however, requires proper models for liposomes and their interaction with the surrounding water molecules. Here, we present an MD-based approach for the theoretical prediction of R1=1/T1, the dependence of R1 on water concentration and the magnetization exchange between lipids and interacting water layer in lipids and lipid mixtures. Moreover, a new parameter is introduced which quantitatively measures the amount of hydration water (hydration water fraction, f_HW) based on conventional spoiled gradient echo MR acquisitions. Both f_HW and the magnetisation exchange rate between lipids and hydration water were determined quantitatively from spoiled gradient echo data. We observed that liposome systems behaved similarly, apart from PLPC which showed both lower hydration water fraction and lower exchange rate. The extracted parameters accurately predicted the measured water fraction-dependent R1 rates and allowed for a theoretical understanding of MR parameters in liposomes of different composition. |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_2408_17085 |
| institution | arXiv |
| publishDate | 2024 |
| record_format | arxiv |
| spellingShingle | A theoretical framework for the assessment of water fraction-dependent longitudinal decay rates and magnetisation transfer in membrane lipid phantoms Neeb, Heiko Schyboll, Felix Shaharabani, Rona Mezer, Aviv A. Shtangel, Oshrat Medical Physics Biological Physics Phantom systems consisting of liposome suspensions are widely employed to investigate quantitative MRI parameters mimicking cellular membranes. The proper physical understanding of the measurement results, however, requires proper models for liposomes and their interaction with the surrounding water molecules. Here, we present an MD-based approach for the theoretical prediction of R1=1/T1, the dependence of R1 on water concentration and the magnetization exchange between lipids and interacting water layer in lipids and lipid mixtures. Moreover, a new parameter is introduced which quantitatively measures the amount of hydration water (hydration water fraction, f_HW) based on conventional spoiled gradient echo MR acquisitions. Both f_HW and the magnetisation exchange rate between lipids and hydration water were determined quantitatively from spoiled gradient echo data. We observed that liposome systems behaved similarly, apart from PLPC which showed both lower hydration water fraction and lower exchange rate. The extracted parameters accurately predicted the measured water fraction-dependent R1 rates and allowed for a theoretical understanding of MR parameters in liposomes of different composition. |
| title | A theoretical framework for the assessment of water fraction-dependent longitudinal decay rates and magnetisation transfer in membrane lipid phantoms |
| topic | Medical Physics Biological Physics |
| url | https://arxiv.org/abs/2408.17085 |