Gisela E. Hagberg1, Aneta Keliris2, Ilgar Mamedov3, Matteo Placidi3, Hellmut Merkle4, Nikos K. Logothetis3, Klaus Scheffler1, 2
1Biomedical Magnetic Resonance, University Hospital Tuebingen, Tuebingen, Germany; 2High-field Magnetic Resonance, Max Planck Institute for Biological Cybernetics, Tuebingen, Germany; 3Physiology of Cognitive Processes, Max Planck Institute for Biological Cybernetics, Tuebingen, Germany; 4LFMI-NINDS, National Institutes of Health, Bethesda, MD, United States
19F-labelled compounds have unique benefits for biological applications but are hampered by low sensitivity. Lanthanide-complexes that shorten the 19F T1 and T2 relaxation times can boost the SNR in spoiled gradient echo sequences (FLASH). We investigated the MRI signal systematically for a wide range of T1 and T2 times for FLASH and balanced steady state free precession (tFISP). For long T2 times the tFISP signal is always greater, and for short relaxation times the signal gain depends on the duration of encoding and spoiling. None of the available compounds had ideal relaxation times that gives the highest possible signal. Our results can be used to design better 19F contrast agents tailored to a specific MRI sequence.