ABSTRACT
PURPOSE: The purpose of this study was to develop an X-Band electron paramagnetic resonance imaging protocol for visualization of oxidative stress in biopsies. METHODS: The developed electron paramagnetic resonance imaging protocol was based on spin trapping with the cyclic hydroxylamine spin probe 1-hydroxy-3-methoxycarbonyl-2,2,5,5-tetramethylpyrrolidine and X-Band EPR imaging. Computer software was developed for deconvolution and back-projection of the EPR image. A phantom containing radicals of known spatial characteristic was used for evaluation of the developed protocol. As a demonstration of the technique electron paramagnetic resonance imaging of oxidative stress was performed in six sections of atherosclerotic plaques. Histopathological analyses were performed on adjoining sections. RESULTS: The developed computer software for deconvolution and back-projection of the EPR images could accurately reproduce the shape of a phantom of known spatial distribution of radicals. The developed protocol could successfully be used to image oxidative stress in six sections of the three ex vivo atherosclerotic plaques. CONCLUSIONS: We have shown that oxidative stress can be imaged using a combination of spin trapping with the cyclic hydroxylamine spin probe cyclic hydroxylamine spin probe 1-hydroxy-3-methoxycarbonyl-2,2,5,5-tetramethylpyrrolidine and X-Band EPR imaging. A thorough and systematic evaluation on different types of biopsies must be performed in the future to validate the proposed technique.
Subject(s)
Carotid Arteries/metabolism , Electron Spin Resonance Spectroscopy/methods , Magnetic Resonance Imaging/methods , Molecular Imaging/methods , Oxidative Stress , Reactive Oxygen Species/metabolism , Aged , Aged, 80 and over , Biopsy/methods , Carotid Arteries/pathology , Female , Humans , Male , Middle Aged , Tissue Distribution , User-Computer InterfaceABSTRACT
Electron paramagnetic resonance (EPR) spectroscopy has been successfully employed to determine radiation dose using alanine. The EPR signal intensity reflects the number of stable free radicals produced, and provides a quantitative measurement of the absorbed dose. The aim of the present study was to explore whether this principle can be extended to provide information on spatial dose distribution using EPR imaging (EPRI). Lithium formate was selected because irradiation induces a single EPR line, a characteristic that is particularly convenient for imaging purposes. (125)I-brachytherapy seeds were inserted in tablets made of lithium formate. Images were acquired at 1.1 GHz. Monte Carlo (MC) calculations were used for comparison. The dose gradient can be determined using two-dimensional (2D) EPR images. Quantitative data correlated with the dose estimated by the MC simulations, although differences were observed. This study provides a first proof-of-concept that EPRI can be used to estimate the gradient dose distribution in phantoms after irradiation.
