Preclinical 19F MRI cell tracking at 3 Tesla

PurposeTo develop methods for fluorine-19 (F-19) MRI cell tracking in mice on a 3Tesla clinical scanner. Compared to iron-based cell tracking, F-19 MRI has lower sensitivity and, consequently, preclinical F-19 cell tracking has only been performed at relatively high magnetic field strengths (>3T). Here, we focus on using F-19 MRI to detect macrophages in tumors; macrophage density is an indication of tumor aggressiveness and, therefore, F-19 MRI could be used as an imaging biomarker.MethodsPerfluorocarbon (PFC)-labeled macrophages were imaged at 3T and NMR spectroscopy was performed to validate F-19 spin quantification. In vivo F-19 MRI was performed on tumor-bearing mice, post-PFC at both 9.4T and 3T. 3T MRI utilized varying NEX and F-19 images were analyzed two different ways for F-19 quantification.ResultsAs few as 25,000 cells could be detected as cell pellets at 3T. F-19 quantification in cell pellets by 3T MRI agreed with NMR spectroscopy. F-19 signal was observed in the liver, spleen and tumor in all mice at 9.4T and 3T and there was no significant difference in F-19 spin quantification.ConclusionThis study demonstrates the ability to detect and quantify F-19 signal in murine tumors using F-19 MRI at 3T.