Purpose: To enhance the SNR in MRI within a localized region of interest using a novel interventional wireless RF resonator probe combined with a dual-drive pTx system. Methods: A dual-drive body birdcage coil was operated in a linearly-polarized mode to decouple a passive RF resonator probe from the transmit field while maintaining the resonator in a receive-only coupled mode. The resonator was fabricated using standard microfabrication techniques and tuned to the Larmor frequency of a 3T MRI system. The 10-g specific absorption rate (SAR) distribution was simulated to identify potential hot spots around the resonator prior to heating experiments. To evaluate the interaction between the resonator probe and the linearly-polarized transmit field, SNR and flip-angle distributions were measured in a phantom. In vivo imaging studies were subsequently performed using the resonator probe in conjunction with the linearly polarized dual-drive birdcage coil. Results: Temperature measurements demonstrated a normalized temperature increase of less than 0.10 degrees, corresponding to a SAR value below 1.21 W/kg. Experimental flip-angle mapping confirmed effective magnetic decoupling of the resonator probe using linearly-polarized dual-drive transmission. An SNR enhancement factor of 1.6 was achieved within the region of interest in phantom experiments. In vivo imaging demonstrated a 2.0-fold SNR enhancement in the vicinity of the resonator probe. Conclusion: A novel interventional approach for localized SNR enhancement in MRI was demonstrated using a wireless RF resonator probe and a dual-drive pTx system. The proposed technique enables local signal enhancement while minimizing transmit-field interactions, thereby facilitating safe interventional MRI and potentially improving image quality and diagnostic performance.
Alipour, A., Acikel, V., Gokyar, S., Algin, O., Oto, C., Balchandani, P., Demir, H. V., Atalar, E.
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