The fractionated dipole antenna: A new antenna for body imaging at 7 Tesla.

Abstract:

PURPOSE:Dipole antennas in ultrahigh field MRI have demonstrated advantages over more conventional designs. In this study, the fractionated dipole antenna is presented: a dipole where the legs are split into segments that are interconnected by capacitors or inductors. METHODS:A parameter study has been performed on dipole antenna length using numerical simulations. A subsequent simulation study investigates the optimal intersegment capacitor/inductor value. The resulting optimal design has been constructed and compared to a previous design, the single-side adapted dipole (SSAD) by simulations and measurements. An array of eight elements has been constructed for prostate imaging on four subjects (body mass index 20-27.5) using 8 × 2 kW amplifiers. RESULTS:For prostate imaging at 7T, lowest peak local specific-absorption rate (SAR) levels are achieved if the antenna is 30 cm or longer. A fractionated dipole antenna design with inductors between segments has been chosen to achieve even lower SAR levels and more homogeneous receive sensitivities. CONCLUSION:With the new design, good quality prostate images are acquired. SAR levels are reduced by 41% to 63% in comparison to the SSAD. Coupling levels are moderate (average nearest neighbor: -14.6 dB) for each subject and prostate B1+ levels range from 12 to 18 μT.

journal_name

Magn Reson Med

authors

Raaijmakers AJ,Italiaander M,Voogt IJ,Luijten PR,Hoogduin JM,Klomp DW,van den Berg CA

doi

10.1002/mrm.25596

subject

Has Abstract

pub_date

2016-03-01 00:00:00

pages

1366-74

issue

3

eissn

0740-3194

issn

1522-2594

journal_volume

75

pub_type

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