Preclinical 19F MRI cell tracking at 3 Tesla
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To develop methods for fluorine-19 (19F) MRI cell tracking in mice on a 3 Tesla clinical scanner. Compared to iron-based cell tracking, 19F MRI has lower sensitivity and, consequently, preclinical 19F cell tracking has only been performed at relatively high magnetic field strengths (> 3 T). Here, we focus on using 19F MRI to detect macrophages in tumors; macrophage density is an indication of tumor aggressiveness and, therefore, 19F MRI could be used as an imaging biomarker.
Perfluorocarbon (PFC)-labeled macrophages were imaged at 3 T and NMR spectroscopy was performed to validate 19F spin quantification. In vivo 19F MRI was performed on tumor-bearing mice, post-PFC at both 9.4 T and 3 T. 3 T MRI utilized varying NEX and 19F images were analyzed two different ways for 19F quantification.
As few as 25,000 cells could be detected as cell pellets at 3 T. 19F quantification in cell pellets by 3 T MRI agreed with NMR spectroscopy. 19F signal was observed in the liver, spleen and tumor in all mice at 9.4 T and 3 T and there was no significant difference in 19F spin quantification.
This study demonstrates the ability to detect and quantify 19F signal in murine tumors using 19F MRI at 3 T.
Keywords19-Fluorine (19F) Magnetic resonance imaging (MRI) Cancer Cell tracking Tumor-associated macrophage (TAM)
We acknowledge the following sources of funding for AVM: Natural Sciences and Engineering Research Council, Molecular Imaging Graduate Program (Western University), Translational Breast Cancer Research Unit, Cancer Research and Technology Transfer Program and Canadian Cancer Society.
AVM study conception and design, acquisition of data, analysis and interpretation of data, drafting of manuscript and critical revision. PJF study conception and design, drafting of manuscript and critical revision.
This study was funded by: Canadian Institute for Health Research.
Compliance with ethical standards
Conflict of interest
The authors declare that they have no conflict of interest.
All procedures performed in studies involving animals were in accordance with the ethical standards of the institution or practice at which the studies were conducted.
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