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dc.contributor.authorSchmidt, MAen_US
dc.contributor.authorWells, EJen_US
dc.contributor.authorDavison, Ken_US
dc.contributor.authorRiddell, AMen_US
dc.contributor.authorWelsh, Len_US
dc.contributor.authorSaran, Fen_US
dc.date.accessioned2018-02-14T15:09:51Z
dc.date.issued2017-02en_US
dc.identifier.citationMedical physics, 2017, 44 (2), pp. 375 - 381en_US
dc.identifier.issn0094-2405en_US
dc.identifier.urihttps://repository.icr.ac.uk/handle/internal/1080
dc.identifier.eissn2473-4209en_US
dc.identifier.doi10.1002/mp.12068en_US
dc.description.abstract<h4>Purpose</h4>MRI is a mandatory requirement to accurately plan Stereotactic Radiosurgery (SRS) for Vestibular Schwannomas. However, MRI may be distorted due not only to inhomogeneity of the static magnetic field and gradients but also due to susceptibility-induced effects, which are more prominent at higher magnetic fields. We assess geometrical distortions around air spaces and consider MRI protocol requirements for SRS planning at 3 T.<h4>Methods</h4>Hardware-related distortion and the effect of incorrect shimming were investigated with structured test objects. The magnetic field was mapped over the head on five volunteers to assess susceptibility-related distortion in the naso-oro-pharyngeal cavities (NOPC) and around the internal ear canal (IAC).<h4>Results</h4>Hardware-related geometric displacements were found to be less than 0.45 mm within the head volume, after distortion correction. Shimming errors can lead to displacements of up to 4 mm, but errors of this magnitude are unlikely to arise in practice. Susceptibility-related field inhomogeneity was under 3.4 ppm, 2.8 ppm, and 2.7 ppm for the head, NOPC region and IAC region, respectively. For the SRS planning protocol (890 Hz/pixel, approximately 1 mm<sup>3</sup> isotropic), susceptibility-related displacements were less than 0.5 mm (head), and 0.4 mm (IAC and NOPC). Large displacements are possible in MRI examinations undertaken with lower receiver bandwidth values, commonly used in clinical MRI. Higher receiver bandwidth makes the protocol less vulnerable to sub-optimal shimming. The shimming volume and the CT-MR co-registration must be considered jointly.<h4>Conclusion</h4>Geometric displacements can be kept under 1 mm in the vicinity of air spaces within the head at 3 T with appropriate setting of the receiver bandwidth, correct shimming and employing distortion correction.en_US
dc.formatPrinten_US
dc.format.extent375 - 381en_US
dc.languageengen_US
dc.language.isoengen_US
dc.subjectHeaden_US
dc.subjectHumansen_US
dc.subjectNeuroma, Acousticen_US
dc.subjectImaging, Three-Dimensionalen_US
dc.subjectMagnetic Resonance Imagingen_US
dc.subjectRadiosurgeryen_US
dc.subjectRadiotherapy Planning, Computer-Assisteden_US
dc.subjectArtifactsen_US
dc.titleStereotactic radiosurgery planning of vestibular schwannomas: Is MRI at 3 Tesla geometrically accurate?en_US
dc.typeJournal Article
dcterms.dateAccepted2016-12-14en_US
rioxxterms.versionofrecord10.1002/mp.12068en_US
rioxxterms.licenseref.urihttps://creativecommons.org/licenses/by/4.0en_US
rioxxterms.licenseref.startdate2017-02en_US
rioxxterms.typeJournal Article/Reviewen_US
dc.relation.isPartOfMedical physicsen_US
pubs.issue2en_US
pubs.notesNot knownen_US
pubs.organisational-group/ICR
pubs.organisational-group/ICR/Primary Group
pubs.organisational-group/ICR/Primary Group/Royal Marsden Clinical Units
pubs.publication-statusPublisheden_US
pubs.volume44en_US
pubs.embargo.termsNot knownen_US
dc.contributor.icrauthorMarsden,en_US


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