Charlotte Sappo1,2, Gary R Drake1,3, Xinqiang Yan1,3, and William A Grissom1,2,3,4
1Vanderbilt University Institute of Imaging Science, Nashville, TN, United States, 2Biomedical Engineering, Vanderbilt University, Nashville, TN, United States, 3Radiology, Vanderbilt University, Nashville, TN, United States, 4Electrical and Computer Engineering, Vanderbilt University, Nashville, TN, United States
1Vanderbilt University Institute of Imaging Science, Nashville, TN, United States, 2Biomedical Engineering, Vanderbilt University, Nashville, TN, United States, 3Radiology, Vanderbilt University, Nashville, TN, United States, 4Electrical and Computer Engineering, Vanderbilt University, Nashville, TN, United States
A 30-channel pTx coil is validated on the bench in phantom measurements for array-compressed parallel transmission. The design presented will enable the mitigation of B1+ field inhomogeneities and control over specific absorption rate in human imaging experiments in the future.
Fig 3. A. Side and top views of the constructed 30-element coil. B. The Nova 32-channel receive coil inserted to show the excellent fit inside the coil. The receive coil sits on an acrylic part so that the pTx coil can slide easily without moving the patient from the helmet. C. The 30-element coil without the shield is shown in detail. All coils are tuned and matching to 298MHz and have a lattice balun at the feedport to reduce cable currents. The head-shaped phantom (The Monster Makers, Cleveland, OH, USA) was filled with a tissue-mimicking solution to tune and match the coil on the bench.
Fig 4. A. The simulation results from a 2x2 self-decoupled and overlapped array in Ansys HFSS (Canonsburg, PA, USA). This decoupling strategy is used throughout the constructed 30-element coil. B. The plot shown is the S11 measurements for all 30 coils at 298MHz. C. A selected set of coupling bench results are shown for a section of the array (coils 2,3,4,12,13,14,22,23,24) for ease of understanding. These decoupling results carry over for the entire coil. All measurements were taken on a Keysight 4-port VNA E5071C and ports that were not being used were terminated using a 50-ohm load.