Transient effects in π-pulse sequences in MAS solid-state NMR

Hellwagner, Johannes; Wili, Nino; Wittmann, J.; Meier, Beat H.; Ibáñez, Luis Fábregas

doi:10.1016/j.jmr.2017.12.015

Cited by 13 publications

(17 citation statements)

References 41 publications

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“…Due to our inclusion criteria, the results of this study only apply to a selected patient group and must not be generalized for patients with recurrent myocardial infarction or other cardiac pathologies that entail left ventricular remodeling. However, with an overall incidence rate of STEMI of 43 to 144 per 100,000 in Europe [47], specific data for this particular group should be available to support clinical decision-making.…”

Section: Limitationsmentioning

confidence: 99%

Mitral annular plane systolic excursion by cardiac MR is an easy tool for optimized prognosis assessment in ST-elevation myocardial infarction

Mayr¹,

Pamminger²,

Reindl³

et al. 2019

Eur Radiol

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Objectives The purpose of this study was to assess the comparative prognostic value of mitral annular plane systolic excursion (MAPSE) versus left ventricular ejection fraction (LVEF), measured by cardiac magnetic resonance (CMR) imaging in patients with ST-elevation myocardial infarction (STEMI) treated with primary percutaneous coronary intervention (pPCI). Methods CMR was performed in 255 STEMI patients within 2 days (interquartile range (IQR) 2-4 days) after infarction. CMR included MAPSE measurement on CINE 4-chamber view. Patients were followed for major adverse cardiovascular events (MACE)-death, non-fatal myocardial re-infarction, stroke, and new congestive heart failure. Results Patients with MACE (n = 35, 14%, median follow-up 3 years [IQR 1-4 years]) showed significantly lower MAPSE (8 mm [7-8.8] vs. 9.6 mm [8.1-11.5], p < 0.001). The association between decreased MAPSE (< 9 mm, optimal cutoff value by c-statistics) remained significant after adjustment for independent clinical and CMR predictors of MACE. The AUC of MAPSE for the prediction of MACE was 0.74 (CI 95% 0.65-0.82), significantly higher than that of LVEF (0.61 [CI 95% 0.50-0.71]; p < 0.001). Conclusions Reduced long-axis function assessed with MAPSE measurement using CINE CMR independently predicts longterm prognosis following STEMI. Moreover, MAPSE provided significantly higher prognostic implication in comparison with conventional LVEF measurement. Key Points • MAPSE determined by CMR independently predicts long-term prognosis following STEMI. • MACE-free survival is significantly higher in patients with MAPSE ≥ 9 mm than < 9 mm. • MAPSE provides significantly higher prognostic implication than conventional LVEF.

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Section: Limitationsmentioning

confidence: 99%

Mitral annular plane systolic excursion by cardiac MR is an easy tool for optimized prognosis assessment in ST-elevation myocardial infarction

Mayr¹,

Pamminger²,

Reindl³

et al. 2019

Eur Radiol

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“…In this article, we investigate the influence of multiple parameters on the residual linewidth in FSLG decoupled spectra. We characterize the magnitude of the broadening by pulse transients for a standard FSLG sequence and compare the results to an implementation using transient-compensated pulses (Hellwagner et al, 2018;Tabuchi et al, 2010;Takeda et al, 2009;Wittmann et al, 2015Wittmann et al, , 2016. Furthermore, we analyze the FSLG sequence theoretically using Floquet theory up to third-order.…”

Section: Open Accessmentioning

confidence: 99%

Origin of the Residual Linewidth Under FSLG-Based Homonuclear Decoupling in MAS Solid-State NMR

Hellwagner

Grunwald

Ochsner

et al. 2019

Preprint

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Abstract. Homonuclear decoupling sequences in solid-state NMR under magic-angle spinning (MAS) show experimentally significantly larger residual linewidth than expected from Floquet theory to second order. We present an in-depth theoretical and experimental analysis of the origin of the residual linewidth in frequency-switched Lee-Goldburg (FSLG) based decoupling sequences. We analyze the effect of experimental pulse-shape errors (e.g. pulse transients and B1-field inhomogeneities) and use a Floquet-theory based description of higher-order error terms that arise from the interference between the MAS rotation and the pulse sequence. It is shown that the magnitude of the third-order auto term of a single homo- or heteronuclear coupled spin pair is important and leads to significant line broadening under FSLG decoupling. Furthermore, we show the dependence of these third-order error terms on the angle of the effective field with the B0 field. An analysis of second-order cross terms is presented that shows that the influence of three-spin terms is small since they are averaged by the pulse sequence. The importance of the static rf-field inhomogeneity is discussed and shown to be the main source of residual line broadening while pulse transients do not seem to play an important role. Experimentally, the influence of the combination of these error terms is shown by using restricted samples and pulse-transient compensation. The results show that all terms are additive but the major contribution to the residual linewidth comes from the rf-field inhomogeneity for the standard implementation of FSLG sequences, which is significant even for samples with a restricted volume.

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“…To further reduce the residual line width, especially at slow and medium-range MAS frequencies (lower than 60 kHz), homonuclear decoupling sequences can be employed. The first strategy to average out homonuclear proton-proton interactions using radio-frequency (rf) fields in static samples was suggested by Lee and Goldburg (Goldburg and Lee, 1963;Lee and Goldburg, 1965). Since then, many homonuclear decoupling sequences have been developed including solid-echo-based sequences (WAHUHA; Waugh et al, 1968, MREV;Mansfield and Grannell, 1971;Rhim et al, 1973), (Burum and Rhim, 1979a, b), time-reversal sequences (Rhim et al, 1971), C-and R-symmetry-based sequences (Levitt, 2007;Madhu et al, 2001;Paul et al, 2010), tilted magic-echo-based sequences (Gan et al, 2011;Lu et al, 2012;Nishiyama et al, 2012), and computer-optimized sequences like DUMBO (Grimminck et al, 2011;Halse and Emsley, 2012;Sakellariou et al, 2000;Salager et al, 2009).…”

Section: Introductionmentioning

confidence: 99%

“…The theoretical basis of the Lee-Goldburg sequence relies on the manipulation of the spin interactions by an offresonance irradiation such that the quantization axis of the effective field is along the magic angle in a rotating frame (Lee and Goldburg, 1965). This leads to the removal of all secondrank interactions in spin space, i.e., the dipolar coupling, to second order in static samples.…”

Section: Introductionmentioning

confidence: 99%

Origin of the residual line width under frequency-switched Lee–Goldburg decoupling in MAS solid-state NMR

et al. 2020

Self Cite

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Abstract. Homonuclear decoupling sequences in solid-state nuclear magnetic resonance (NMR) under magic-angle spinning (MAS) show experimentally significantly larger residual line width than expected from Floquet theory to second order. We present an in-depth theoretical and experimental analysis of the origin of the residual line width under decoupling based on frequency-switched Lee–Goldburg (FSLG) sequences. We analyze the effect of experimental pulse-shape errors (e.g., pulse transients and B1-field inhomogeneities) and use a Floquet-theory-based description of higher-order error terms that arise from the interference between the MAS rotation and the pulse sequence. It is shown that the magnitude of the third-order auto term of a single homo- or heteronuclear coupled spin pair is important and leads to significant line broadening under FSLG decoupling. Furthermore, we show the dependence of these third-order error terms on the angle of the effective field with the B0 field. An analysis of second-order cross terms is presented that shows that the influence of three-spin terms is small since they are averaged by the pulse sequence. The importance of the inhomogeneity of the radio-frequency (rf) field is discussed and shown to be the main source of residual line broadening while pulse transients do not seem to play an important role. Experimentally, the influence of the combination of these error terms is shown by using restricted samples and pulse-transient compensation. The results show that all terms are additive but the major contribution to the residual line width comes from the rf-field inhomogeneity for the standard implementation of FSLG sequences, which is significant even for samples with a restricted volume.

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Transient effects in π-pulse sequences in MAS solid-state NMR

Cited by 13 publications

References 41 publications

Mitral annular plane systolic excursion by cardiac MR is an easy tool for optimized prognosis assessment in ST-elevation myocardial infarction

Mitral annular plane systolic excursion by cardiac MR is an easy tool for optimized prognosis assessment in ST-elevation myocardial infarction

Origin of the Residual Linewidth Under FSLG-Based Homonuclear Decoupling in MAS Solid-State NMR

Origin of the residual line width under frequency-switched Lee–Goldburg decoupling in MAS solid-state NMR

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