title: Proton-Electron Double-Resonance Imaging of pH using phosphonated trityl probe.
abstract: Variable Radio Frequency Proton-Electron Double-Resonance Imaging (VRF PEDRI) enables extracting a functional map from a limited number of images acquired at pre-selected EPR frequencies using specifically designed paramagnetic probes with high quality spatial resolution and short acquisition times. In this work we explored potential of VRF PEDRI for pH mapping of aqueous samples using recently synthesized pH-sensitive phosphonated trityl radical, pTR. The ratio of Overhauser enhancements measured at each pixel at two different excitation frequencies corresponding to the resonances of protonated and deprotonated forms of pTR probe allows for a pH map extraction. Long relaxation times of pTR allow for pH mapping at EPR irradiation power as low as 1.25 W during 130 s acquisition time with spatial resolution of about 1 mm. This is particularly important forin vivoapplications enabling one to avoid sample overheating by reducing RF power deposition.
authors.affiliation: Division of Pulmonary, Allergy, Critical Care & Sleep Medicine, Department of Internal Medicine and Dorothy M. Davis Heart & Lung Research Institute, The Ohio State University, Columbus, OH, USA ; Division of Bioengineering and Bioinformatics, Graduate School of Information Science and Technology, Hokkaido University, Sapporo, Japan.
authors.forename: Wataru
authors.initials: W
authors.lastname: Takahashi
authors.affiliation: Division of Pulmonary, Allergy, Critical Care & Sleep Medicine, Department of Internal Medicine and Dorothy M. Davis Heart & Lung Research Institute, The Ohio State University, Columbus, OH, USA.
authors.forename: Andrey A
authors.initials: AA
authors.lastname: Bobko
authors.affiliation: Division of Pulmonary, Allergy, Critical Care & Sleep Medicine, Department of Internal Medicine and Dorothy M. Davis Heart & Lung Research Institute, The Ohio State University, Columbus, OH, USA.
authors.forename: Ilirian
authors.initials: I
authors.lastname: Dhimitruka
authors.affiliation: Division of Bioengineering and Bioinformatics, Graduate School of Information Science and Technology, Hokkaido University, Sapporo, Japan.
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Hirata
authors.affiliation: Division of Cardiology and Dorothy M. Davis Heart & Lung Research Institute, Department of Internal Medicine, The Ohio State University, Columbus, OH, USA.
authors.forename: Jay L
authors.initials: JL
authors.lastname: Zweier
authors.affiliation: Division of Cardiology and Dorothy M. Davis Heart & Lung Research Institute, Department of Internal Medicine, The Ohio State University, Columbus, OH, USA.
authors.forename: Alexandre
authors.initials: A
authors.lastname: Samouilov
authors.affiliation: Division of Pulmonary, Allergy, Critical Care & Sleep Medicine, Department of Internal Medicine and Dorothy M. Davis Heart & Lung Research Institute, The Ohio State University, Columbus, OH, USA.
authors.forename: Valery V
authors.initials: VV
authors.lastname: Khramtsov
keywords: Overhauser-enhanced magnetic resonance imaging; PH mapping; Proton-Electron Double-Resonance Imaging; Trityl radical