Sheared two-dimensional radiofrequency excitation for off-resonance robustness and fat suppression in reduced field-of-view imaging

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buir.contributor.authorBarlas, Bahadır Alp
buir.contributor.authorBahadır, Çağla Deniz
buir.contributor.authorKafalı, Sevgi Gökçe
buir.contributor.authorYılmaz, Uğur
buir.contributor.authorSarıtaş, Emine Ülkü
buir.contributor.orcidBarlas, Bahadır Alp|0000-0001-6963-9644
buir.contributor.orcidBahadır, Çağla Deniz|0000-0003-2247-9975
buir.contributor.orcidKafalı, Sevgi Gökçe|0000-0001-5941-5399
buir.contributor.orcidSarıtaş, Emine Ülkü|0000-0001-8551-1077
dc.citation.epage2519en_US
dc.citation.issueNumber6en_US
dc.citation.spage2504en_US
dc.citation.volumeNumber88en_US
dc.contributor.authorBarlas, Bahadır Alp
dc.contributor.authorBahadır, Çağla Deniz
dc.contributor.authorKafalı, Sevgi Gökçe
dc.contributor.authorYılmaz, Uğur
dc.contributor.authorSarıtaş, Emine Ülkü
dc.date.accessioned2023-02-13T11:27:58Z
dc.date.available2023-02-13T11:27:58Z
dc.date.issued2022-09-30
dc.departmentDepartment of Electrical and Electronics Engineeringen_US
dc.departmentGraduate School of Engineering and Scienceen_US
dc.departmentInterdisciplinary Program in Neuroscience (NEUROSCIENCE)en_US
dc.departmentNational Magnetic Resonance Research Center (UMRAM)en_US
dc.description.abstractPurpose: Two-dimensional (2D) echo-planar radiofrequency (RF) pulses are widely used for reduced field-of-view (FOV) imaging in applications such as diffusion-weighted imaging. However, long pulse durations render the 2D RF pulses sensitive to off-resonance effects, causing local signal losses in reduced-FOV images. This work aims to achieve off-resonance robustness for 2D RF pulses via a sheared trajectory design. Theory and Methods: A sheared 2D RF pulse design is proposed to reduce pulse durations while covering identical excitation k-space extent as a standard 2D RF pulse. For a given shear angle, the number of sheared trajectory lines is minimized to obtain the shortest pulse duration, such that the excitation replicas are repositioned outside the slice stack to guarantee unlimited slice coverage. A target fat/water signal ratio of 5% is chosen to achieve robust fat suppression. Results: Simulations, imaging experiments on a custom head and neck phantom, and in vivo imaging experiments in the spinal cord at 3 T demonstrate that the sheared 2D RF design provides significant improvement in image quality while preserving profile sharpnesses. In regions with high off-resonance effects, the sheared 2D RF pulse improves the signal by more than 50% when compared to the standard 2D RF pulse. Conclusion: The proposed sheared 2D RF design successfully reduces pulse durations, exhibiting significantly improved through-plane off-resonance robustness, while providing unlimited slice coverage and high fidelity fat suppression. This method will be especially beneficial in regions suffering from a variety of off-resonance effects, such as spinal cord and breast. © 2022 International Society for Magnetic Resonance in Medicine.en_US
dc.description.provenanceSubmitted by Evrim Ergin (eergin@bilkent.edu.tr) on 2023-02-13T11:27:58Z No. of bitstreams: 1 Sheared_two_dimensional_radiofrequency_excitation-for_off_resonance-robustness.pdf: 2483250 bytes, checksum: 48deba47b96bce73140a1d17015e43ae (MD5)en
dc.description.provenanceMade available in DSpace on 2023-02-13T11:27:58Z (GMT). No. of bitstreams: 1 Sheared_two_dimensional_radiofrequency_excitation-for_off_resonance-robustness.pdf: 2483250 bytes, checksum: 48deba47b96bce73140a1d17015e43ae (MD5) Previous issue date: 2022-09-30en
dc.identifier.doi10.1002/mrm.29416en_US
dc.identifier.eissn1522-2594
dc.identifier.issn0740-3194
dc.identifier.urihttp://hdl.handle.net/11693/111213
dc.language.isoEnglishen_US
dc.publisherWileyen_US
dc.relation.isversionofhttps://doi.org/10.1002/mrm.29416en_US
dc.source.titleMagnetic Resonance in Medicineen_US
dc.subject2D RF pulseen_US
dc.subjectFat suppressionen_US
dc.subjectMultislice imagingen_US
dc.subjectOff-resonance robustnessen_US
dc.subjectReduced field-of-view imagingen_US
dc.subjectSheared trajectoryen_US
dc.titleSheared two-dimensional radiofrequency excitation for off-resonance robustness and fat suppression in reduced field-of-view imagingen_US
dc.typeArticleen_US

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