| Zugriffsnummer | 45331 |
| Dokumenttyp | Zeitschriftenartikel |
| Peer Review | mit Peer Review |
| Sprache | Englisch |
| Titel | Fast online-customized (FOCUS) parallel transmission pulses: A combination of universal pulses and individual optimization |
| Autor(in); Institution |
Herrler, Jürgen; Department of Neuroradiology, University Hospital Erlangen, Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), Erlangen, GERMANY
Liebig, Patrick; Siemens Healthineers GmbH, Erlangen, GERMANY
Gumbrecht, Rene; Siemens Healthineers GmbH, Erlangen, GERMANY
Ritter, Dieter; Siemens Healthineers GmbH, Erlangen, GERMANY
Schmitter, Sebastian; 8.1, Biomedizinische Magnetresonanz, PTB-Berlin
Maier, Andreas; Department of Computer Science, Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), GERMANY
Schmidt, Manuel; Department of Neuroradiology, University Hospital Erlangen, Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), Erlangen, GERMANY
Uder, Michael; Department of Neuroradiology, University Hospital Erlangen, Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), Erlangen, GERMANY
Doerfler, Arnd; Siemens Healthineers GmbH, Erlangen, GERMANY
Nagel, Armin M.; Institute of Radiology, University Hospital Erlangen, Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), Erlangen, GERMANY
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| Quelle/Jahr | Magnetic Resonance in Medicine: 85 (2021), 6, 3140 - 3153 |
| ISSN | 0740-3194 (PRINT) ; 1522-2594 (ONLINE) |
| DOI | |
| Verlag | London: Wiley |
| Zusammenfassung | Purpose: To mitigate spatial flip angle (FA) variations under strict specific absorption rate (SAR) constraints for ultra-high field MRI using a combination of universal parallel transmit (pTx) pulses and fast subject-specific optimization. Methods: Data sets consisting of B0, B+1 maps, and virtual observation point (VOP) data were acquired from 72 subjects (study groups of 48/12 healthy uropeans/Asians and 12 Europeans with pathological or incidental findings) using an 8Tx/32Rx head coil on a 7T whole-body MR system. Combined optimization values (COV) were defined as combination of spiral-nonselective (SPINS) trajectory parameters and an energy regularization weight. A set of COV was optimized universally by simulating the individual RF pulse optimizations of 12 training data sets (healthy Europeans). Subsequently, corresponding universal pulses (UPs) were calculated. Using COV and UPs, individually optimized pulses (IOPs) were calculated during the sequence preparation phase (maximum 15 s). Two different UPs and IOPs were evaluated by calculating their normalized root-mean-square error (NRMSE) of the FA and SAR in simulations of all data sets. Seven additional subjects were examined using an MPRAGE sequence that uses the designed pTx excitation pulses and a conventional adiabatic inversion. Results: All pTx pulses resulted in decreased mean NRMSE compared to a circularly polarized (CP) pulse (CP = ~28%, UPs = ~17%, and IOPs = ~12%). UPs and IOPs improved homogeneity for all subjects. Differences in NRMSE between study groups were much lower than differences between different pulse types. Conclusion: UPs can be used to generate fast online-customized (FOCUS) pulses gaining lower NRMSE and/or lower SAR values. |
| Kostenfreier Zugang | Open Access Hybrid |
| Rechteinformation | CC BY 4.0 ; Creative Commons Attribution 4.0 License |
| Themenbereich der Metrologie | Metrologie in der Medizin |
| Förderinformationen (1) |
Förderername: Siemens Healthcare GmbH
Förderer ID: 0000 0004 0623 2494 Förderer ID Typ: ISNI |
Zitierung
Herrler, J., Liebig, P., Gumbrecht, R., Ritter, D., Schmitter, S., Maier, A., Schmidt, M., Uder, M., Doerfler, A., & Nagel, A. M. (2021). Fast online-customized (FOCUS) parallel transmission pulses: A combination of universal pulses and individual optimization. Magnetic Resonance in Medicine, 85(6), 3140–3153. https://doi.org/10.1002/mrm.28643