Interventional MRI: tapering improves the distal sensitivity of the loopless antenna

buir.contributor.authorAtalar, Ergin
dc.citation.epage802en_US
dc.citation.issueNumber3en_US
dc.citation.spage797en_US
dc.citation.volumeNumber63en_US
dc.contributor.authorQian, D.en_US
dc.contributor.authorEl-Sharkawy, A. M. M.en_US
dc.contributor.authorAtalar, Erginen_US
dc.contributor.authorBottomley, P. A.en_US
dc.date.accessioned2016-02-08T09:59:48Z
dc.date.available2016-02-08T09:59:48Z
dc.date.issued2010en_US
dc.departmentDepartment of Electrical and Electronics Engineeringen_US
dc.description.abstractThe "loopless antenna" is an interventional MRI detector consisting of a tuned coaxial cable and an extended inner conductor or "whip". A limitation is the poor sensitivity afforded at, and immediately proximal to, its distal end, which is exacerbated by the extended whip length when the whip is uniformly insulated. It is shown here that tapered insulation dramatically improves the distal sensitivity of the loopless antenna by pushing the current sensitivity toward the tip. The absolute signal-to-noise ratio is numerically computed by the electromagnetic method-of-moments for three resonant 3-T antennae with no insulation, uniform insulation, and with linearly tapered insulation. The analysis shows that tapered insulation provides an ∼400% increase in signal-to-noise ratio in trans-axial planes 1 cm from the tip and a 16-fold increase in the sensitive area as compared to an equivalent, uniformly insulated antenna. These findings are directly confirmed by phantom experiments and by MRI of an aorta specimen. The results demonstrate that numerical electromagnetic signal-tonoise ratio analysis can accurately predict the loopless detector's signal-to-noise ratio and play a central role in optimizing its design. The manifold improvement in distal signal-to-noise ratio afforded by redistributing the insulation should improve the loopless antenna's utility for interventional MRI.en_US
dc.identifier.doi10.1002/mrm.22152en_US
dc.identifier.issn0740-3194
dc.identifier.urihttp://hdl.handle.net/11693/22415
dc.language.isoEnglishen_US
dc.publisherWileyen_US
dc.relation.isversionofhttp://dx.doi.org/10.1002/mrm.22152en_US
dc.source.titleMagnetic Resonance in Medicineen_US
dc.subjectInterventional MRIen_US
dc.subjectIntravascular MRIen_US
dc.subjectLoopless antennaen_US
dc.subjectMRI detectorsen_US
dc.subjectSignal-to-noise ratioen_US
dc.subjectaccuracyen_US
dc.subjectaortaen_US
dc.subjectDielectric constanten_US
dc.subjectElectromagnetic fielden_US
dc.subjectSurgery, Computer-Assisteden_US
dc.titleInterventional MRI: tapering improves the distal sensitivity of the loopless antennaen_US
dc.typeArticleen_US
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