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Abstract #4264

Analyse the Important Fitted Parameters Using Pulsed Fitting and Continuous CEST Approximation for Pulsed CEST

Yee Kai Tee1, Alexandr A. Khrapichev2, Nicola R. Sibson2, Stephen J. Payne1, Michael A. Chappell1, 3

1Department of Engineering Science, Institute of Biomedical Engineering, University of Oxford, Oxford, Oxfordshire, United Kingdom; 2Department of Oncology, CR-UK/MRC Gray Institute for Radiation Oncology & Biology, University of Oxford, Oxford, Oxfordshire, United Kingdom; 3Oxford Centre for Functional MRI of the Brain, University of Oxford, Oxford, Oxfordshire, United Kingdom

Pulsed CEST (PC) is the only feasible irradiation scheme for clinical application as a result of SAR and hardware limitations but there is no simple analytical solution available. Thus, it is typically treated as continuous CEST (CC) by finding its equivalent average field or power to exploit the closed-form analytical solution of CC. Although fitting the data by discretizing the short pulses used by PC is able to produce smaller fitted errors, there is no significant difference found for the important fitted parameters such as amide proton exchange rate (related to pH) when CC approximation, which is fast, is used.

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Keywords

able absorption according advantages agents agreement amide analytical applied approximation approximations assess assumed available bandwidth bars become better bigger biology biomedical cancer chemical clinical closed collects compute concentration conditions continuous correlated delay determined differentiated discretized done duration duty easy engineering equivalent errors except exchange exists expected experiment exploit field final finding fits fitted fitting form former frequency generated good gray hardware identical important initial institute interval irradiation kingdom largest latter like limitations literature long magnetization maps matrix measured model much near needed nevertheless next novel numerical offer offsets oncology optimal oxford permitted phantom phantoms planar plots plotted pool power predominantly prepared propagate properties proton protons pulse pulsed pulses quantification radiation readout rectangular refer related remaining reproducing residual sampling saturation scheme segments serving setting short simulate simulated simulation since slice solution solving spectra spectrometer spectrum stroke suitable tailed technologies tissue transfer translation treated types typically unavoidable variables varying view water whereas zero