Ashley V Makela1,2, Paula J Foster3,4. 1. Robarts Research Institute, London, ON, Canada. amakela@uwo.ca. 2. The Department of Medical Biophysics, Western University, 1151 Richmond Street North, London, ON, N6A 5B7, Canada. amakela@uwo.ca. 3. Robarts Research Institute, London, ON, Canada. 4. The Department of Medical Biophysics, Western University, 1151 Richmond Street North, London, ON, N6A 5B7, Canada.
Abstract
PURPOSE: 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. METHODS: 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. RESULTS: 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. CONCLUSION: This study demonstrates the ability to detect and quantify 19F signal in murine tumors using 19F MRI at 3 T.
PURPOSE: 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. METHODS: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. RESULTS: 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. CONCLUSION: This study demonstrates the ability to detect and quantify 19F signal in murinetumors using 19F MRI at 3 T.