Academic Journal
Optimizing Selective RF Pulses for Enhanced Signal Stability in Turbo Spin Echo Using a Differentiable Extended Phase Graph Model.
| Title: | Optimizing Selective RF Pulses for Enhanced Signal Stability in Turbo Spin Echo Using a Differentiable Extended Phase Graph Model. |
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| Authors: | Augelli MM; Biomedical Engineering, Case Western Reserve University, Cleveland, Ohio, USA., Sharma A; Biomedical Engineering, Case Western Reserve University, Cleveland, Ohio, USA., Griswold MA; Biomedical Engineering, Case Western Reserve University, Cleveland, Ohio, USA.; Department of Radiology, Case Western Reserve University, Cleveland, Ohio, USA., Grissom WA; Biomedical Engineering, Case Western Reserve University, Cleveland, Ohio, USA.; Department of Radiology, Case Western Reserve University, Cleveland, Ohio, USA. |
| Source: | Magnetic resonance in medicine [Magn Reson Med] 2026 Jul; Vol. 96 (1), pp. 214-226. Date of Electronic Publication: 2026 Mar 12. |
| Publication Type: | Journal Article |
| Language: | English |
| Journal Info: | 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 |
| MeSH Terms: | Magnetic Resonance Imaging*/methods , Image Enhancement*/methods , Brain*/diagnostic imaging , Image Interpretation, Computer-Assisted*/methods , Image Processing, Computer-Assisted*/methods, Phantoms, Imaging ; Algorithms ; Humans ; Radio Waves ; Reproducibility of Results ; Computer Simulation ; Signal Processing, Computer-Assisted ; Artifacts |
| Abstract: | Purpose: To improve slice profile consistency across echo trains in turbo spin echo (TSE) imaging, thereby reducing image blurring and increasing the accuracy of multi echo spin echo INLINEMATH mapping. Methods: Excitation and refocusing RF pulses were optimized for TSE using a differentiable extended phase graph model that incorporates the spinor profiles of the RF pulses to calculate the magnetization slice profile across the echo train. The pulses were optimized using an L-BFGS algorithm in PyTorch to minimize an error term on the target signal magnitude with singular value regularization to promote similarity. The performance of the optimized pulses was assessed by comparing to time bandwidth-matched SLR RF pulses. Slice profile consistency was calculated in simulation and in a homogeneous phantom. Images were acquired in vivo to assess blurring artifacts, and INLINEMATH measurements were acquired in a NIST phantom and in vivo to assess improvements in accuracy. Results: The optimized pulses demonstrated superior performance over time bandwidth-matched SLR pulses, with a 90% reduction in the standard deviation of the normalized integrated signal at each echo. Optimized pulses increased sharpness in vivo at the edges of CSF and veins perpendicular to the phase-encoded direction, reduced INLINEMATH mapping error in the NIST phantom by 91%, and produced more accurate in vivo INLINEMATH maps. Conclusion: The optimization method enables flexible design of RF pulses in echo train pulse sequences with consistent slice profiles, achieving a target signal progression while also maintaining a constant phase and FWHM between echoes. (© 2026 The Author(s). Magnetic Resonance in Medicine published by Wiley Periodicals LLC on behalf of International Society for Magnetic Resonance in Medicine.) |
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| Grant Information: | GRFP 2437833 National Science Foundation; Siemens Healthineers; R01 CA 281043 United States NH NIH HHS; R01 EB 019437 United States NH NIH HHS; T32 EB 007509 United States NH NIH HHS |
| Contributed Indexing: | Keywords: RF pulse design; extended phase graph; optimization; turbo spin echo |
| Entry Date(s): | Date Created: 20260312 Date Completed: 20260710 Latest Revision: 20260813 |
| Update Code: | 20260813 |
| PubMed Central ID: | PMC13156457 |
| DOI: | 10.1002/mrm.70340 |
| PMID: | 41820234 |
| Database: | MEDLINE |
| ISSN: | 1522-2594 |
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| DOI: | 10.1002/mrm.70340 |