Lu, Ming; Jiang, Xiaoyu; Ma, Yajun; Qian, Yurui; Liao, Congyu; Yang, Yang; Gore, John C.; Yan, Xinqiang. (2026).听.听NMR in Biomedicine, 39(11), e70408.听
Wireless resonators can improve MRI performance, but they must safely deactivate, or 鈥渄etune,鈥� when exposed to the scanner鈥檚 transmitted radiofrequency power. We developed a simple method to determine the power level at which this detuning becomes reliable. Using MRI scans of test objects, the method compares signals near and farther from the resonator across different transmit-power levels to identify the detuning threshold. Testing with several resonator designs, MRI field strengths (3 and 7T), and scanners from different manufacturers produced consistent results. This approach provides a practical tool for testing and monitoring the safety of wireless resonators used in clinical and research MRI.
FIGURE 1
Passive detuning of wireless resonators. (A)聽Illustration of the induced current in the wireless resonator during RF transmission. (B)聽Crossed diodes in parallel with a distributed capacitor (capacitor shorted when diodes conduct). (C)聽Crossed diodes with a series inductor in parallel with a distributed capacitor (capacitor effectively open-circuited when diodes conduct). (D)聽Coaxial coil implementation with diodes placed across the gap of the open ends. The ellipses indicate the presence of multiple distributed capacitors along the conductor.