Transmit Power Optimization for Multimode Coil
نویسندگان
چکیده
Introduction: In previous work, we introduced the concept of the multimode coil [1]. The multimode coil consists of a tracking coil connected in series with a multi-turn imaging coil and simultaneously performs the functions of active tip tracking, imaging and inductively coupled wireless marker. The tracking and imaging coils have conflicting design requirements. While the region of sensitivity of the tracking coil must be highly localized, that of the imaging coil must reach as far as possible. In addition, the tracking peak must dominate the overall signal profile of the coil in order to enable robust tracking. Furthermore, the multimode coil is inductively coupled to the external transmit or transmit/receive coil as the case may be in order to enable the wireless marker functionality. This results in the magnification of the transmit B1 field within the region of sensitivity of the multimode coil, leading to larger flip angles compared to regions outside the coil sensitivity. Furthermore, the magnification of the B1 field due to the tracking component of the multimode coil is greater than that due to the imaging component. Optimization of the transmit power from the external transmit coil is therefore necessary to enable robust tip tracking and imaging.
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