title: Multi-turn multi-gap transmission line resonators - Concept, design and first implementation at 4.7T and 7T.
abstract: A novel design scheme for monolithic transmission line resonators (TLRs) is presented - the multi-turn multi-gap TLR (MTMG-TLR) design. The MTMG-TLR design enables the construction of TLRs with multiple turns and multiple gaps. This presents an additional degree of freedom in tuning self-resonant TLRs, as their resonance frequency is fully determined by the coil geometry (e.g. diameter, number of turns, conductor width, etc.). The novel design is evaluated at 4.7T and 7T by simulations and experiments, where it is demonstrated that MTMG-TLRs can be used for MRI, and that the B1distribution of MTMG-TLRs strongly depends on the number and distribution of turns. A comparison to conventional loop coils revealed that the B1performance of MTMG-TLRs is comparable to a loop coil with the same mean diameter; however, lower 10g SAR values were found for MTMG-TLRs. The MTMG-TLR design is expected to bring most benefits at high static field, where it allows for independent size and frequency selection, which cannot be achieved with standard TLR design. However, it also enables more accurate geometric optimization at low static field. Thereby, the MTMG-TLR design preserves the intrinsic advantages of TLRs, i.e. mechanical flexibility, high SAR efficiency, mass production, and coil miniaturization.
authors.affiliation: Center for Medical Physics and Biomedical Engineering, Medical University of Vienna, Währinger Gürtel 18-20, 1090 Vienna, Austria; MR Centre of Excellence, Medical University of Vienna, Lazarettgasse 14, 1090 Vienna, Austria. Electronic address: roberta.frass@meduniwien.ac.at.
authors.forename: Roberta
authors.initials: R
authors.lastname: Frass-Kriegl
authors.affiliation: Center for Medical Physics and Biomedical Engineering, Medical University of Vienna, Währinger Gürtel 18-20, 1090 Vienna, Austria; MR Centre of Excellence, Medical University of Vienna, Lazarettgasse 14, 1090 Vienna, Austria.
authors.forename: Elmar
authors.initials: E
authors.lastname: Laistler
authors.affiliation: Center for Medical Physics and Biomedical Engineering, Medical University of Vienna, Währinger Gürtel 18-20, 1090 Vienna, Austria; MR Centre of Excellence, Medical University of Vienna, Lazarettgasse 14, 1090 Vienna, Austria; Laboratoire d'Imagerie par Résonance Magnétique Médicale et Multi-Modalités (IR4M), Université Paris-Sud, CNRS, Université Paris-Saclay, Bâtiment 220, Rue André Ampère, 91405 Orsay, France.
authors.forename: Sajad
authors.initials: S
authors.lastname: Hosseinnezhadian
authors.affiliation: Center for Medical Physics and Biomedical Engineering, Medical University of Vienna, Währinger Gürtel 18-20, 1090 Vienna, Austria; MR Centre of Excellence, Medical University of Vienna, Lazarettgasse 14, 1090 Vienna, Austria.
authors.forename: Albrecht Ingo
authors.initials: AI
authors.lastname: Schmid
authors.affiliation: Center for Medical Physics and Biomedical Engineering, Medical University of Vienna, Währinger Gürtel 18-20, 1090 Vienna, Austria; MR Centre of Excellence, Medical University of Vienna, Lazarettgasse 14, 1090 Vienna, Austria.
authors.forename: Ewald
authors.initials: E
authors.lastname: Moser
authors.affiliation: Laboratoire d'Imagerie par Résonance Magnétique Médicale et Multi-Modalités (IR4M), Université Paris-Sud, CNRS, Université Paris-Saclay, Bâtiment 220, Rue André Ampère, 91405 Orsay, France.
authors.forename: Marie
authors.initials: M
authors.lastname: Poirier-Quinot
authors.affiliation: Laboratoire d'Imagerie par Résonance Magnétique Médicale et Multi-Modalités (IR4M), Université Paris-Sud, CNRS, Université Paris-Saclay, Bâtiment 220, Rue André Ampère, 91405 Orsay, France.
authors.forename: Luc
authors.initials: L
authors.lastname: Darrasse
authors.affiliation: Laboratoire d'Imagerie par Résonance Magnétique Médicale et Multi-Modalités (IR4M), Université Paris-Sud, CNRS, Université Paris-Saclay, Bâtiment 220, Rue André Ampère, 91405 Orsay, France.
authors.forename: Jean-Christophe
authors.initials: JC
authors.lastname: Ginefri
keywords: B(1) mapping; EM simulation; High-field MRI; RF coil; Surface coil; Transmission line resonator