Manus J. Donahue1,
  Anna Tietze2, 3, Irene Klaerke Mikkelsen2,
  Leif Ostergaard2, Megan Strother1, Seth Smith1,
  Jakob Blicher2, 4
 1Radiology
  and Radiological Sciences, Vanderbilt University, Nashville, TN, United
  States; 2Center for Functionally Integrative Neuroscience, Aarhus
  University Hospital, Aarhus, Denmark; 3Neuroradiology, Aarhus
  University Hospital, Aarhus, Denmark; 4Hammel Neurorehabilitation
  and Research, Aarhus University Hospital, Hammel, Denmark
The purpose of this study is to apply a pH-sensitive CEST protocol in acute (≤4.5 hrs post-onset) and subacute (4.5-24 hrs post-onset) stroke patients to understand the extent to which amide proton transfer (APT) contrast may be used to identify metabolically-impaired tissue at highest risk for infarction. CEST provides unique contrast compared to DWI and PWI in tissue that progresses to infarction by one-month follow up. We also discuss ongoing limitations of CEST in the acute stroke setting and provide an outline of technical hurdles that must be overcome before CEST may be applied routinely in this important patient population.