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Fast Online 3D SPACE and FLAIR Imaging at 7T Using Multiple Subject-Specific Parallel Transmission Pulses Based on Subpopulation Universal Pulses.

Λεπτομέρειες βιβλιογραφικής εγγραφής
Τίτλος: Fast Online 3D SPACE and FLAIR Imaging at 7T Using Multiple Subject-Specific Parallel Transmission Pulses Based on Subpopulation Universal Pulses.
Συγγραφείς: Oran OF; Siemens Medical Solutions USA Inc., Palo Alto, California, USA., Herrler J; Siemens Healthineers AG, Forchheim, Germany., Liebig PA; Siemens Healthineers AG, Forchheim, Germany., Gati JS; Centre for Functional and Metabolic Mapping, Western University, London, Ontario, Canada.; Department of Medical Biophysics, Western University, London, Ontario, Canada., Klassen LM; Centre for Functional and Metabolic Mapping, Western University, London, Ontario, Canada., Menon RS; Centre for Functional and Metabolic Mapping, Western University, London, Ontario, Canada.; Department of Medical Biophysics, Western University, London, Ontario, Canada.
Πηγή: Magnetic resonance in medicine [Magn Reson Med] 2026 Aug; Vol. 96 (2), pp. 771-786. Date of Electronic Publication: 2026 Apr 19.
Τύπος έκδοσης: Journal Article
Γλώσσα: English
Στοιχεία περιοδικού: Publisher: Wiley Country of Publication: United States NLM ID: 8505245 Publication Model: Print-Electronic Cited Medium: Internet ISSN: 1522-2594 (Electronic) Linking ISSN: 07403194 NLM ISO Abbreviation: Magn Reson Med Subsets: MEDLINE
Imprint Name(s): Publication: 1999- : New York, NY : Wiley
Original Publication: San Diego : Academic Press
Ιατρικοί όροι (MeSH): Magnetic Resonance Imaging*/methods , Imaging, Three-Dimensional*/methods , Brain*/diagnostic imaging , Image Processing, Computer-Assisted*/methods, Image Enhancement/methods ; Humans ; Algorithms ; Artifacts ; Radio Waves ; Male ; Adult ; Female ; Signal Processing, Computer-Assisted ; Reproducibility of Results
Περίληψη: Purpose: In 3D SPACE and FLAIR sequences, designing single pTx RF pulse for excitation and refocusing pulses by scaling its amplitude can introduce artifacts. This study addresses this by designing multiple subject-specific RF pulses online within clinically viable times, using subpopulation universal pulses (UPs) as initialization.
Methods: Subpopulation UPs were calculated using INLINEMATH and INLINEMATH maps from 150 training subjects. During experiments, refocusing flip-angles were grouped into five clusters. Starting from the subpopulation UP yielding the lowest error, a reference RF pulse was optimized for the cluster with mean flip-angle closest to 90°. The remaining refocusing-cluster and excitation RF pulses were optimized using the reference phase response, with refocusing RF pulses scaled to desired flip-angles. Time-symmetric RF and anti-symmetric gradient waveforms were enforced as a constraint. For FLAIR, a new T2-prepared inversion scheme was proposed, based on designing a symmetric 180° inversion pTx pulse and splitting it to obtain 90° pulses.
Results: Compared to INLINEMATH -shimming and single-RF pulse optimization, the proposed method minimized artifacts resulting from RF pulse scaling, particularly in high INLINEMATH regions. Online pulse calculations required ∼20 s and an additional ∼9 s for FLAIR. Across 120 test subjects, the multi-RF approach demonstrated an 18% improvement in the simulated echo magnitude within high INLINEMATH regions and 13% improvement within the brain. pTx inversion pulses achieved an 86% SAR reduction compared to adiabatic ones.
Conclusion: The proposed method enables efficient subject-specific RF pulse design for 3D SPACE and FLAIR.
(© 2026 International Society for Magnetic Resonance in Medicine.)
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Grant Information: 4888 Fondation Brain Canada; RGPIN-2019-04743 Natural Sciences and Engineering Research Council of Canada; Canada First Research Excellence Fund (BrainsCAN)
Contributed Indexing: Keywords: FLAIR; FOCUS; SPACE; T2‐prepared inversion; dynamic pTx; subpopulation universal pulses; ultra‐high field MRI; universal pulses
Entry Date(s): Date Created: 20260420 Date Completed: 20260615 Latest Revision: 20260615
Update Code: 20260616
DOI: 10.1002/mrm.70387
PMID: 42003222
Βάση Δεδομένων: MEDLINE
Περιγραφή
ISSN:1522-2594
DOI:10.1002/mrm.70387