Wideband Self-Grounded Bow-Tie Antenna for Thermal MR
Journal article, 2020

The objective of this study was the design, implementation, evaluation and application of a compact wideband self-grounded bow-tie (SGBT) radiofrequency (RF) antenna building block that supports anatomical proton (H-1) MRI, fluorine (F-19) MRI, MR thermometry and broadband thermal intervention integrated in a whole-body 7.0 T system. Design considerations and optimizations were conducted with numerical electromagnetic field (EMF) simulations to facilitate a broadband thermal intervention frequency of the RF antenna building block. RF transmission (B-1(+)) field efficiency and specific absorption rate (SAR) were obtained in a phantom, and the thigh of human voxel models (Ella, Duke) for H-1 and F-19 MRI at 7.0 T. B-1(+) efficiency simulations were validated with actual flip-angle imaging measurements. The feasibility of thermal intervention was examined by temperature simulations (f = 300, 400 and 500 MHz) in a phantom. The RF heating intervention (P-in = 100 W, t = 120 seconds) was validated experimentally using the proton resonance shift method and fiberoptic probes for temperature monitoring. The applicability of the SGBT RF antenna building block for in vivo H-1 and F-19 MRI was demonstrated for the thigh and forearm of a healthy volunteer. The SGBT RF antenna building block facilitated F-19 and H-1 MRI at 7.0 T as well as broadband thermal intervention (234-561 MHz). For the thigh of the human voxel models, a B-1(+) efficiency >= 11.8 mu T/root kW was achieved at a depth of 50 mm. Temperature simulations and heating experiments in a phantom demonstrated a temperature increase Delta T >7 K at a depth of 10 mm. The compact SGBT antenna building block provides technology for the design of integrated high-density RF applicators and for the study of the role of temperature in (patho-) physiological processes by adding a thermal intervention dimension to an MRI device (Thermal MR).

radiofrequency antenna

self-grounded bow-tie

thermal intervention

broadband antenna

ultrahigh field MR

thermal magnetic resonance

magnetic resonance

Author

Thomas Wilhelm Eigentler

Technische Universität Berlin

Max Delbruck Ctr Mol Med Helmholtz Assoc

Lukas Winter

Max Delbruck Ctr Mol Med Helmholtz Assoc

Physikalisch-Technische Bundesanstalt (PTB)

Haopeng Han

Max Delbruck Ctr Mol Med Helmholtz Assoc

Humboldt University of Berlin

Eva Oberacker

Max Delbruck Ctr Mol Med Helmholtz Assoc

Andre Kuehne

MRI TOOLS GmbH

Helmar Waiczies

MRI TOOLS GmbH

Sebastian Schmitter

Physikalisch-Technische Bundesanstalt (PTB)

Laura Boehmert

Berlin Institute of Health

Humboldt University of Berlin

Charité University Medicine Berlin

Max Delbruck Ctr Mol Med Helmholtz Assoc

Freie Universität Berlin

Christian Prinz

Charité University Medicine Berlin

Max Delbruck Ctr Mol Med Helmholtz Assoc

Humboldt University of Berlin

Freie Universität Berlin

Berlin Institute of Health

Hana Dobsicek Trefna

Chalmers, Electrical Engineering, Signalbehandling och medicinsk teknik, Biomedical Electromagnetics

Thoralf Niendorf

ECRC

MRI TOOLS GmbH

Max Delbruck Ctr Mol Med Helmholtz Assoc

NMR in Biomedicine

0952-3480 (ISSN) 1099-1492 (eISSN)

Vol. 33 5 e4274

Subject Categories

Energy Engineering

Building Technologies

Other Electrical Engineering, Electronic Engineering, Information Engineering

DOI

10.1002/nbm.4274

PubMed

32078208

More information

Latest update

5/20/2020