Decoupling of a tight-fit transceiver phased array for human brain imaging at 9.4T: Loop overlapping rediscovered

Nikolai I. Avdievich, Ioannis Angelos Giapitzakis, Andreas Pfrommer, Anke Henning

Research output: Contribution to journalArticlepeer-review

13 Scopus citations

Abstract

Purpose: To improve the decoupling of a transceiver human head phased array at ultra-high fields (UHF, ≥ 7T) and to optimize its transmit (Tx) and receive (Rx) performance, a single-row eight-element (1 × 8) tight-fit transceiver overlapped loop array was developed and constructed. Overlapping the loops increases the RF field penetration depth but can compromise decoupling by generating substantial mutual resistance. Methods: Based on analytical modeling, we optimized the loop geometry and relative positioning to simultaneously minimize the resistive and inductive coupling and constructed a 9.4T eight-loop transceiver head phased array decoupled entirely by overlapping loops. Results: We demonstrated that both the magnetic and electric coupling between adjacent loops is compensated at the same time by overlapping and nearly perfect decoupling (below -30 dB) can be obtained without additional decoupling strategies. Tx-efficiency and SNR of the overlapped array outperformed that of a common UHF gapped array of similar dimensions. Parallel Rx-performance was also not compromised due to overlapping the loops. Conclusion: As a proof of concept we developed and constructed a 9.4T (400 MHz) overlapped transceiver head array based on results of the analytical modeling. We demonstrated that at UHF overlapping loops not only provides excellent decoupling but also improves both Tx- and Rx-performance. Magn Reson Med 79:1200–1211, 2018.

Original languageEnglish (US)
Pages (from-to)1200-1211
Number of pages12
JournalMagnetic resonance in medicine
Volume79
Issue number2
DOIs
StatePublished - Feb 1 2018

Keywords

  • SNR improvement
  • analytical modeling
  • array optimization
  • transceiver arrays
  • ultra-high field MRI, decoupling

ASJC Scopus subject areas

  • Radiology Nuclear Medicine and imaging

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