Rapid, B1-insensitive, dual-band quasi-adiabatic saturation transfer with optimal control for complete quantification of myocardial ATP flux
<p><strong>Purpose:</strong> Phosphorus saturation-transfer experiments can quantify metabolic fluxes non-invasively. Typically, the forward flux through the creatine-kinase reaction is investigated by observing the decrease in phosphocreatine (PCr) after saturation of γ-ATP. The q...
| Egile Nagusiak: | , , , , , , , , , , |
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| Formatua: | Journal article |
| Hizkuntza: | English |
| Argitaratua: |
Wiley
2021
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| _version_ | 1826298741044281344 |
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| author | Miller, JJ Valkovič, L Kerr, M Timm, KN Watson, WD Lau, JYC Tyler, A Rodgers, C Bottomley, PA Heather, LC Tyler, DJ |
| author_facet | Miller, JJ Valkovič, L Kerr, M Timm, KN Watson, WD Lau, JYC Tyler, A Rodgers, C Bottomley, PA Heather, LC Tyler, DJ |
| author_sort | Miller, JJ |
| collection | OXFORD |
| description | <p><strong>Purpose:</strong> Phosphorus saturation-transfer experiments can quantify metabolic fluxes non-invasively. Typically, the forward flux through the creatine-kinase reaction is investigated by observing the decrease in phosphocreatine (PCr) after saturation of γ-ATP. The quantification of total ATP utilisation is currently under-explored, as it requires simultaneous saturation of inorganic phosphate (Pi) and PCr. This is challenging, as currently available saturation pulses reduce the already-low γ-ATP signal present. </p>
<p><strong>Methods:</strong> Using a hybrid optimal-control and Shinnar-Le-Roux method, a quasi-adiabatic RF pulse was designed for the dual-saturation of PCr and Pi to enable determination of total ATP utilisation. The pulses were evaluated in Bloch equation simulations, compared with a conventional hard-cosine DANTE saturation sequence, before being applied to perfused rat hearts at 11.7 Tesla.
<p><strong>Results:</strong> The quasi-adiabatic pulse was insensitive to a > 2.5-fold variation in B1, producing equivalent saturation with a 53% reduction in delivered pulse power and a 33-fold reduction in spillover at the minimum effective B1. This enabled the complete quantification of the synthesis and degradation fluxes for ATP in 30-45 minutes in the perfused rat heart. While the net synthesis flux (4.24±0.8 mM/s, SEM) was not significantly different from degradation flux (6.88 ± 2 mM/s, p = 0.06) and both measures are consistent with prior work, nonlinear error analysis highlights uncertainties in the Pi-to-ATP measurement that may explain a trend suggesting a possible imbalance. </p>
<p><strong>Conclusion:</strong> This work demonstrates a novel quasi-adiabatic dual-saturation RF pulse with significantly improved performance that can be used to measure ATP turnover in the heart in vivo.</p> |
| first_indexed | 2024-03-07T04:51:26Z |
| format | Journal article |
| id | oxford-uuid:d51ab8f9-de7d-4f83-9bfc-6ee6f4cc828a |
| institution | University of Oxford |
| language | English |
| last_indexed | 2024-03-07T04:51:26Z |
| publishDate | 2021 |
| publisher | Wiley |
| record_format | dspace |
| spelling | oxford-uuid:d51ab8f9-de7d-4f83-9bfc-6ee6f4cc828a2022-03-27T08:23:36ZRapid, B1-insensitive, dual-band quasi-adiabatic saturation transfer with optimal control for complete quantification of myocardial ATP fluxJournal articlehttp://purl.org/coar/resource_type/c_dcae04bcuuid:d51ab8f9-de7d-4f83-9bfc-6ee6f4cc828aEnglishSymplectic ElementsWiley2021Miller, JJValkovič, LKerr, MTimm, KNWatson, WDLau, JYCTyler, ARodgers, CBottomley, PAHeather, LCTyler, DJ<p><strong>Purpose:</strong> Phosphorus saturation-transfer experiments can quantify metabolic fluxes non-invasively. Typically, the forward flux through the creatine-kinase reaction is investigated by observing the decrease in phosphocreatine (PCr) after saturation of γ-ATP. The quantification of total ATP utilisation is currently under-explored, as it requires simultaneous saturation of inorganic phosphate (Pi) and PCr. This is challenging, as currently available saturation pulses reduce the already-low γ-ATP signal present. </p> <p><strong>Methods:</strong> Using a hybrid optimal-control and Shinnar-Le-Roux method, a quasi-adiabatic RF pulse was designed for the dual-saturation of PCr and Pi to enable determination of total ATP utilisation. The pulses were evaluated in Bloch equation simulations, compared with a conventional hard-cosine DANTE saturation sequence, before being applied to perfused rat hearts at 11.7 Tesla. <p><strong>Results:</strong> The quasi-adiabatic pulse was insensitive to a > 2.5-fold variation in B1, producing equivalent saturation with a 53% reduction in delivered pulse power and a 33-fold reduction in spillover at the minimum effective B1. This enabled the complete quantification of the synthesis and degradation fluxes for ATP in 30-45 minutes in the perfused rat heart. While the net synthesis flux (4.24±0.8 mM/s, SEM) was not significantly different from degradation flux (6.88 ± 2 mM/s, p = 0.06) and both measures are consistent with prior work, nonlinear error analysis highlights uncertainties in the Pi-to-ATP measurement that may explain a trend suggesting a possible imbalance. </p> <p><strong>Conclusion:</strong> This work demonstrates a novel quasi-adiabatic dual-saturation RF pulse with significantly improved performance that can be used to measure ATP turnover in the heart in vivo.</p> |
| spellingShingle | Miller, JJ Valkovič, L Kerr, M Timm, KN Watson, WD Lau, JYC Tyler, A Rodgers, C Bottomley, PA Heather, LC Tyler, DJ Rapid, B1-insensitive, dual-band quasi-adiabatic saturation transfer with optimal control for complete quantification of myocardial ATP flux |
| title | Rapid, B1-insensitive, dual-band quasi-adiabatic saturation transfer with optimal control for complete quantification of myocardial ATP flux |
| title_full | Rapid, B1-insensitive, dual-band quasi-adiabatic saturation transfer with optimal control for complete quantification of myocardial ATP flux |
| title_fullStr | Rapid, B1-insensitive, dual-band quasi-adiabatic saturation transfer with optimal control for complete quantification of myocardial ATP flux |
| title_full_unstemmed | Rapid, B1-insensitive, dual-band quasi-adiabatic saturation transfer with optimal control for complete quantification of myocardial ATP flux |
| title_short | Rapid, B1-insensitive, dual-band quasi-adiabatic saturation transfer with optimal control for complete quantification of myocardial ATP flux |
| title_sort | rapid b1 insensitive dual band quasi adiabatic saturation transfer with optimal control for complete quantification of myocardial atp flux |
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