Program Information
Quantitative Evaluation of Excitation Angle Strategy Effects On Detection Accuracy of Hyperpolarized Pyruvate Metabolism
C Walker*, J Bankson , UT MD Anderson Cancer Center, Houston, TX
Presentations
TU-AB-601-9 (Tuesday, August 1, 2017) 7:30 AM - 9:30 AM Room: 601
Purpose: Magnetic resonance signal evolution of hyperpolarized agents is fundamentally different than conventional magnetic resonance. Allowing the excitation angle to change over time has been shown to improve hyperpolarized signal detected by magnetic resonance. However, it is still unclear if such signal increases correspond to more accurate detection of metabolism. In this work variable excitation angle strategies are compared to simpler constant excitation angle strategies on the basis of metabolic rate detection accuracy.
Methods: Signal evolution was simulated by coupling a two physical compartment model of perfusion to a two chemical pool model of hyperpolarized signal evolution. Both broadband and multi-band excitations strategies were compared numerically. Noisy simulation data was fit with the same model of chemical exchange and fit results were compared to simulation parameters to determine accuracy and repeatability.
Results: Simulations show that while variable excitation angle strategies had peak improved lactate signal, they did not improve the accuracy or repeatability of kinetic analyses when compared to constant small excitation strategies. Accounting for perfusion when designing variable excitation strategies does improve accuracy but not enough to outperform constant excitation angle strategies.
Conclusion: These numerical results suggest that the additional complexity and practical limitations of variable excitation strategies may not be justified for quantitative dynamic spectroscopy of hyperpolarized agents. Such variable excitation strategies are likely best suited for imaging techniques where a constant signal is desired during the population of k-space. Accounting for perfusion when designing variable excitation strategies does modestly improve accuracy but not enough to compare favorably against constant excitation angle strategies.
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