Bu S Park1, Ge Ma2, William T Koch2, Sunder S Rajan3, Manuel Mastromanolis2, Johnny Lam2, Kyung Sung2, Brent McCright2. 1. Division of Cellular and Gene Therapies (DCGT)/OTAT/CBER, Food and Drug Administration, Silver Spring, MD, 20993-0002, USA. Bu.Park@fda.hhs.gov. 2. Division of Cellular and Gene Therapies (DCGT)/OTAT/CBER, Food and Drug Administration, Silver Spring, MD, 20993-0002, USA. 3. Division of Biomedical Physics (DBP)/OSEL/CDRH, Food and Drug Administration, Silver Spring, MD, 20993-0002, USA.
Abstract
OBJECTIVE: Improve 19F magnetic resonance imaging uniformity of perfluorocarbon (PFC)-labeled cells by using a secondary inductive resonator tuned to 287 MHz to enhance the induced radio frequency (RF) magnetic field (B1) at 7.05 T. MATERIALS AND METHODS: Following Faraday's induction law, the sign of induced B1 made by the secondary resonator can be changed depending on the tuning of the resonator. A secondary resonator located on the opposite side of the phantom of the 19F surface coil can be shown to enhance or subtract the induced B1 field, depending upon its tuning. RESULTS: The numerical simulation results of rotating transmit B1 magnitude (|B 1 + |) and corresponding experimental 19F images were compared without and with the secondary resonator. With the secondary resonator tuned to 287 MHz, improvements of |B 1 + | and 19F image uniformity were demonstrated. The use of the secondary resonator improved our ability to visualize transplanted cell location non-invasively over a period of 6 weeks. CONCLUSION: The secondary resonator tuned to enhance the induced B1 results in improved image uniformity in a pre-clinical application, enabling cell tracking of PFC-labeled cells with the secondary resonator.
OBJECTIVE: Improve 19F magnetic resonance imaging uniformity of perfluorocarbon (PFC)-labeled cells by using a secondary inductive resonator tuned to 287 MHz to enhance the induced radio frequency (RF) magnetic field (B1) at 7.05 T. MATERIALS AND METHODS: Following Faraday's induction law, the sign of induced B1 made by the secondary resonator can be changed depending on the tuning of the resonator. A secondary resonator located on the opposite side of the phantom of the 19F surface coil can be shown to enhance or subtract the induced B1 field, depending upon its tuning. RESULTS: The numerical simulation results of rotating transmit B1 magnitude (|B 1 + |) and corresponding experimental 19F images were compared without and with the secondary resonator. With the secondary resonator tuned to 287 MHz, improvements of |B 1 + | and 19F image uniformity were demonstrated. The use of the secondary resonator improved our ability to visualize transplanted cell location non-invasively over a period of 6 weeks. CONCLUSION: The secondary resonator tuned to enhance the induced B1 results in improved image uniformity in a pre-clinical application, enabling cell tracking of PFC-labeled cells with the secondary resonator.