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Schlagwörter:
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Zusammenfassung:
Commonly, for optimal MRI performance at low (<3T) magnetic fields, a local receive-only (Rx) RF phased array is used in combination with an integrated transmit-only (Tx) body RF volume coil. This technique is difficult to apply at ultra-high (>7T) magnetic fields (UHF) because large body coils are very inefficient at UHF, and cannot satisfy requirements in RF magnetic field, B1, anymore. To improve Tx-efficiency, B1/√P, and achieve a good Rx-performance, a local Transmit-Only volume coil (or Tx-array) in combination with a smaller tight-fit Receive-Only array, a ToRo coil, is used instead. Since most of the commercial UHF scanners provide only 8 kW of RF power, half of which is lost on a way to the coil, ToRo design still does not deliver sufficient B1. Tight-fit transceiver (TxRx) phased arrays improve Tx-efficiency in comparison to Tx-only arrays, which are larger to fit Rx-only arrays inside. However, the number of elements in a TxRx-array is restricted by the number of available RF Tx-channels (commonly <16) and difficulties associated with decoupling during transmission. In this work, we optimized the decoupling and developed new methods to increase the number of Rx-elements without compromising the Tx-performance. Thus, both the Tx- and Rx-performance of the TxRx-array can be optimized at same time.