Erika Mariotti1, Mattia Veronese2, Joel T Dunn1, Richard Southworth1, Thomas R Eykyn1. 1. Division of Imaging Sciences and Biomedical Engineering, St. Thomas' Hospital, King's College London, London, United Kingdom. 2. Institute of Psychiatry, King's College London, London, United Kingdom.
Abstract
PURPOSE: To assess the feasibility of using a hybrid Maximum-Entropy/Nonlinear Least Squares (MEM/NLS) method for analyzing the kinetics of hyperpolarized dynamic data with minimum a priori knowledge. THEORY AND METHODS: A continuous distribution of rates obtained through the Laplace inversion of the data is used as a constraint on the NLS fitting to derive a discrete spectrum of rates. Performance of the MEM/NLS algorithm was assessed through Monte Carlo simulations and validated by fitting the longitudinal relaxation time curves of hyperpolarized [1-(13) C] pyruvate acquired at 9.4 Tesla and at three different flip angles. The method was further used to assess the kinetics of hyperpolarized pyruvate-lactate exchange acquired in vitro in whole blood and to re-analyze the previously published in vitro reaction of hyperpolarized (15) N choline with choline kinase. RESULTS: The MEM/NLS method was found to be adequate for the kinetic characterization of hyperpolarized in vitro time-series. Additional insights were obtained from experimental data in blood as well as from previously published (15) N choline experimental data. CONCLUSION: The proposed method informs on the compartmental model that best approximate the biological system observed using hyperpolarized (13) C MR especially when the metabolic pathway assessed is complex or a new hyperpolarized probe is used.
PURPOSE: To assess the feasibility of using a hybrid Maximum-Entropy/Nonlinear Least Squares (MEM/NLS) method for analyzing the kinetics of hyperpolarized dynamic data with minimum a priori knowledge. THEORY AND METHODS: A continuous distribution of rates obtained through the Laplace inversion of the data is used as a constraint on the NLS fitting to derive a discrete spectrum of rates. Performance of the MEM/NLS algorithm was assessed through Monte Carlo simulations and validated by fitting the longitudinal relaxation time curves of hyperpolarized [1-(13) C] pyruvate acquired at 9.4 Tesla and at three different flip angles. The method was further used to assess the kinetics of hyperpolarized pyruvate-lactate exchange acquired in vitro in whole blood and to re-analyze the previously published in vitro reaction of hyperpolarized (15) N choline with choline kinase. RESULTS: The MEM/NLS method was found to be adequate for the kinetic characterization of hyperpolarized in vitro time-series. Additional insights were obtained from experimental data in blood as well as from previously published (15) N choline experimental data. CONCLUSION: The proposed method informs on the compartmental model that best approximate the biological system observed using hyperpolarized (13) C MR especially when the metabolic pathway assessed is complex or a new hyperpolarized probe is used.
Authors: James A Bankson; Christopher M Walker; Marc S Ramirez; Wolfgang Stefan; David Fuentes; Matthew E Merritt; Jaehyuk Lee; Vlad C Sandulache; Yunyun Chen; Liem Phan; Ping-Chieh Chou; Arvind Rao; Sai-Ching J Yeung; Mong-Hong Lee; Dawid Schellingerhout; Charles A Conrad; Craig Malloy; A Dean Sherry; Stephen Y Lai; John D Hazle Journal: Cancer Res Date: 2015-09-29 Impact factor: 12.701
Authors: Kiaran P McGee; Ken-Pin Hwang; Daniel C Sullivan; John Kurhanewicz; Yanle Hu; Jihong Wang; Wen Li; Josef Debbins; Eric Paulson; Jeffrey R Olsen; Chia-Ho Hua; Lizette Warner; Daniel Ma; Eduardo Moros; Neelam Tyagi; Caroline Chung Journal: Med Phys Date: 2021-05-20 Impact factor: 4.071