title: Fast dynamic electron paramagnetic resonance (EPR) oxygen imaging using low-rank tensors.
abstract: Hypoxic tumors are resistant to radiotherapy, motivating the development of tools to image local oxygen concentrations. It is generally believed that stable or chronic hypoxia is the source of resistance, but more recent work suggests a role for transient hypoxia. Conventional EPR imaging (EPRI) is capable of imaging tissue pO2in vivo, with high pO2 resolution and 1mm spatial resolution but low imaging speed (10min temporal resolution for T1-based pO2 mapping), which makes it difficult to investigate the oxygen changes, e.g., transient hypoxia. Here we describe a new imaging method which accelerates dynamic EPR oxygen imaging, allowing 3D imaging at 2 frames per minute, fast enough to image transient hypoxia at the "speed limit" of observed pO2 change. The method centers on a low-rank tensor model that decouples the tradeoff between imaging speed, spatial coverage/resolution, and number of inversion times (pO2 accuracy). We present a specialized sparse sampling strategy and image reconstruction algorithm for use with this model. The quality and utility of the method is demonstrated in simulations and in vivo experiments in tumor bearing mice.
authors: Center for EPR Imaging In Vivo Physiology, University of Chicago, Chicago, IL 60637, USA; Department of Electrical and Computer Engineering and Beckman Institute for Advanced Science and Technology, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA.
authors: Anthony G
authors: AG
authors: Christodoulou
authors: Center for EPR Imaging In Vivo Physiology, University of Chicago, Chicago, IL 60637, USA; Department of Radiation and Cellular Oncology, University of Chicago, Chicago, IL 60637, USA.
authors: Gage
authors: G
authors: Redler
authors: Center for EPR Imaging In Vivo Physiology, University of Chicago, Chicago, IL 60637, USA; Department of Electrical and Computer Engineering and Beckman Institute for Advanced Science and Technology, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA.
authors: Bryan
authors: B
authors: Clifford
authors: Center for EPR Imaging In Vivo Physiology, University of Chicago, Chicago, IL 60637, USA; Department of Electrical and Computer Engineering and Beckman Institute for Advanced Science and Technology, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA.
authors: Zhi-Pei
authors: ZP
authors: Liang
authors: Center for EPR Imaging In Vivo Physiology, University of Chicago, Chicago, IL 60637, USA; Department of Radiation and Cellular Oncology, University of Chicago, Chicago, IL 60637, USA.
authors: Howard J
authors: HJ
authors: Halpern
authors: Center for EPR Imaging In Vivo Physiology, University of Chicago, Chicago, IL 60637, USA; Department of Radiation and Cellular Oncology, University of Chicago, Chicago, IL 60637, USA. Electronic address: bepel@uchicago.edu.
authors: Boris
authors: B
authors: Epel
mesh_terms: D000465:Algorithms; D000818:Animals; D004578:Electron Spin Resonance Spectroscopy; D000860:Hypoxia; D007091:Image Processing, Computer-Assisted; D051379:Mice; D009369:Neoplasms / Q000000981:diagnostic imaging*; D010100:Oxygen
chemical_list: D010100:Oxygen
keywords: EPR; Imaging; Oxygen; Sparse sampling