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dc.contributor.authorFreedman, JNen_US
dc.contributor.authorCollins, DJen_US
dc.contributor.authorBainbridge, Hen_US
dc.contributor.authorRank, CMen_US
dc.contributor.authorNill, Sen_US
dc.contributor.authorKachelrieß, Men_US
dc.contributor.authorOelfke, Uen_US
dc.contributor.authorLeach, MOen_US
dc.contributor.authorWetscherek, Aen_US
dc.date.accessioned2017-05-23T14:50:32Z
dc.date.issued2017-10en_US
dc.identifier.citationInvestigative radiology, 2017, 52 (10), pp. 563 - 573en_US
dc.identifier.issn0020-9996en_US
dc.identifier.urihttps://repository.icr.ac.uk/handle/internal/642
dc.identifier.eissn1536-0210en_US
dc.identifier.doi10.1097/rli.0000000000000381en_US
dc.description.abstract<h4>Objectives</h4>The aim of this study was to develop and verify a method to obtain good temporal resolution T2-weighted 4-dimensional (4D-T2w) magnetic resonance imaging (MRI) by using motion information from T1-weighted 4D (4D-T1w) MRI, to support treatment planning in MR-guided radiotherapy.<h4>Materials and methods</h4>Ten patients with primary non-small cell lung cancer were scanned at 1.5 T axially with a volumetric T2-weighted turbo spin echo sequence gated to exhalation and a volumetric T1-weighted stack-of-stars spoiled gradient echo sequence with golden angle spacing acquired in free breathing. From the latter, 20 respiratory phases were reconstructed using the recently developed 4D joint MoCo-HDTV algorithm based on the self-gating signal obtained from the k-space center. Motion vector fields describing the respiratory cycle were obtained by deformable image registration between the respiratory phases and projected onto the T2-weighted image volume. The resulting 4D-T2w volumes were verified against the 4D-T1w volumes: an edge-detection method was used to measure the diaphragm positions; the locations of anatomical landmarks delineated by a radiation oncologist were compared and normalized mutual information was calculated to evaluate volumetric image similarity.<h4>Results</h4>High-resolution 4D-T2w MRI was obtained. Respiratory motion was preserved on calculated 4D-T2w MRI, with median diaphragm positions being consistent with less than 6.6 mm (2 voxels) for all patients and less than 3.3 mm (1 voxel) for 9 of 10 patients. Geometrical positions were coherent between 4D-T1w and 4D-T2w MRI as Euclidean distances between all corresponding anatomical landmarks agreed to within 7.6 mm (Euclidean distance of 2 voxels) and were below 3.8 mm (Euclidean distance of 1 voxel) for 355 of 470 pairs of anatomical landmarks. Volumetric image similarity was commensurate between 4D-T1w and 4D-T2w MRI, as mean percentage differences in normalized mutual information (calculated over all respiratory phases and patients), between corresponding respiratory phases of 4D-T1w and 4D-T2w MRI and the tie-phase of 4D-T1w and 3-dimensional T2w MRI, were consistent to 0.41% ± 0.37%. Four-dimensional T2w MRI displayed tumor extent, structure, and position more clearly than corresponding 4D-T1w MRI, especially when mobile tumor sites were adjacent to organs at risk.<h4>Conclusions</h4>A methodology to obtain 4D-T2w MRI that retrospectively applies the motion information from 4D-T1w MRI to 3-dimensional T2w MRI was developed and verified. Four-dimensional T2w MRI can assist clinicians in delineating mobile lesions that are difficult to define on 4D-T1w MRI, because of poor tumor-tissue contrast.en_US
dc.formatPrinten_US
dc.format.extent563 - 573en_US
dc.languageengen_US
dc.language.isoengen_US
dc.subjectHumansen_US
dc.subjectCarcinoma, Non-Small-Cell Lungen_US
dc.subjectLung Neoplasmsen_US
dc.subjectImaging, Three-Dimensionalen_US
dc.subjectRadiotherapy Planning, Computer-Assisteden_US
dc.subjectAgeden_US
dc.subjectAged, 80 and overen_US
dc.subjectMiddle Ageden_US
dc.subjectFemaleen_US
dc.subjectMaleen_US
dc.subjectMagnetic Resonance Imaging, Interventionalen_US
dc.titleT2-Weighted 4D Magnetic Resonance Imaging for Application in Magnetic Resonance-Guided Radiotherapy Treatment Planning.en_US
dc.typeJournal Article
dcterms.dateAccepted2017-03-20en_US
rioxxterms.versionofrecord10.1097/rli.0000000000000381en_US
rioxxterms.licenseref.urihttps://creativecommons.org/licenses/by/4.0en_US
rioxxterms.licenseref.startdate2017-10en_US
rioxxterms.typeJournal Article/Reviewen_US
dc.relation.isPartOfInvestigative radiologyen_US
pubs.issue10en_US
pubs.notesNo embargoen_US
pubs.organisational-group/ICR
pubs.organisational-group/ICR/Primary Group
pubs.organisational-group/ICR/Primary Group/ICR Divisions
pubs.organisational-group/ICR/Primary Group/ICR Divisions/Radiotherapy and Imaging
pubs.organisational-group/ICR/Primary Group/ICR Divisions/Radiotherapy and Imaging/Magnetic Resonance
pubs.organisational-group/ICR/Primary Group/ICR Divisions/Radiotherapy and Imaging/Radiotherapy Physics Modelling
pubs.organisational-group/ICR/Primary Group/Royal Marsden Clinical Units
pubs.publication-statusPublisheden_US
pubs.volume52en_US
pubs.embargo.termsNo embargoen_US
icr.researchteamMagnetic Resonanceen_US
icr.researchteamRadiotherapy Physics Modellingen_US
dc.contributor.icrauthorFreedman, Joshuaen_US
dc.contributor.icrauthorOelfke, Uween_US
dc.contributor.icrauthorLeach, Martinen_US
dc.contributor.icrauthorNill, Simeonen_US
dc.contributor.icrauthorMarsden,en_US
dc.contributor.icrauthorBainbridge, Hannahen_US
dc.contributor.icrauthorWetscherek, Andreasen_US


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