Purpose A calibration‐free pulse design method is introduced to alleviate B1+ artifacts in clinical routine with parallel transmission at high field, dealing with significant inter‐subject variability, found for instance in the abdomen. Theory and Methods From a dual‐transmit 3T scanner, a database of B1+ and off‐resonance abdominal maps from 50 subjects was first divided into 3 clusters based on mutual affinity between their respective tailored kT‐points pulses. For each cluster, a kT‐points pulse was computed, minimizing normalized root‐mean‐square flip angle deviations simultaneously for all subjects comprised in it. Using 30 additional subjects' field distributions, a machine learning classifier was trained on this 80‐labeled‐subject database to recognize the best pulse from the 3 ones available, relying only on patient features accessible from the preliminary localizer sequence present in all protocols. This so‐called SmartPulse process was experimentally tested on an additional 53‐subject set and compared with other pulse types: vendor's hard calibration‐free dual excitation, tailored static radiofrequency shimming, universal and tailored kT‐points pulses. Results SmartPulse outperformed both calibration‐free approaches. Tailored static radiofrequency shimming yielded similar flip angle homogeneity for most patients but broke down for some while SmartPulse remained robust. Although flip angle homogeneity was systematically better with tailored kT‐points, the difference was barely noticeable on in vivo images. Conclusion The proposed method paves the way toward an efficient trade‐off between tailored and universal pulse design approaches for large inter‐subject variability. With no need for on‐line field mapping or pulse design, it can fit seamlessly into a clinical protocol.
People interested in the research are advised to contact the author for the final version of the publication, or visit the DOI to the publisher's website.• The final author version and the galley proof are versions of the publication after peer review.• The final published version features the final layout of the paper including the volume, issue and page numbers. Link to publication General rightsCopyright and moral rights for the publications made accessible in the public portal are retained by the authors and/or other copyright owners and it is a condition of accessing publications that users recognise and abide by the legal requirements associated with these rights.• Users may download and print one copy of any publication from the public portal for the purpose of private study or research. • You may not further distribute the material or use it for any profit-making activity or commercial gain • You may freely distribute the URL identifying the publication in the public portal.If the publication is distributed under the terms of Article 25fa of the Dutch Copyright Act, indicated by the "Taverne" license above, please follow below link for the End User Agreement:
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.