Currently, tcMRgFUS treatments are done in the body coil for both transmit and receive. Virtually no MRI is done with the body coil today because local coils provide better SNR than the body coil. However, off- the-shelf coils cannot be used in this application due to 1) the water bath, since coils are not built to sustain water immersion, and 2) the transducer, which for 13 of the 15 systems has a conducting surface and is therefore an RF shield. As a result, positioning the coil as close to the head as possible and in the water bath is a must. In fact, the coil must optimize sensitivity at the plane of the membrane (the focus of the transducer) and thus has to reside on both sides of the membrane. The coil must have a low profile in order to allow as much transmission of ultrasound as possible. Lastly, it must overcome the dielectric artifact which is present due to the conductive matching layer used for the trandsducer (graphite). While graphite is the state-of-the-art for transducer design and optimizes transducer efficiency, it distorts the RF field, with low signal at a half wavelength from the transducer surface (15 cm at 3T), exactly at the transducer focus
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