Denmark – Scanners – Delivery of Gradient Coil for human magnetic resonance imaging

DTU needs to purchase a uniaxial resonant head insert gradient coil for animal and human magnetic resonance imaging (MRI), particularly for hydrogen and hyperpolarized carbon-13 MRI. We aim for 3D mapping of brain metabolites with a time resolution of around a second for calculation of metabolic rates. This requires gradient performance exceeding that of clinical scanners. To drive the gradient coil at the needed slew rate and current with an MRI gradient amplifier, it needs to be resonant, so it amplifies the output at specific frequencies multi-fold. An integrated capacitor bank is needed to make the coil resonant at around 10 kHz for carbon-13, and 20 kHz for hydrogen to make the data acquisition quiet for fMRI (Versteeg et al, Magn Reson Med. 2022;87:1062–1073). To compensate for the low gyromagnetic ratio of carbon-13, an efficiency of around 0.3 mT/m/A is needed. At 10 kHz, it must sustain maximum voltages and currents of 1.8 kV and 300 A (4.8 kV and 225 A at 20 kHz). The maximum duty cycle needs to be near 100% during the lifetime of the carbon MRI signal, i.e., 2 minutes. The application shall include functional MRI with visual stimulation, so the gradient coil needs to be open in front of the subject eyes. Since the coil will only be relevant for a patient sub-group, it needs to be mountable and configured within an hour to enable flexible use of the scanner with intermittent coil use required to enable clinical translation. The coil needs to be designed, built and equipped with safety measures (sensors) so it can be approved for human use, even though CE labelling is not a requirement. Market research has shown, that the only supplier of resonant human-suited head insert gradient coils is Futura Composites BV that can fulfill the requirements above. Therefore, DTU intends to issue a purchase order to the company.