title: Measuring extracellular pH in a lung fibrosis model with acidoCEST MRI.
abstract: OBJECTIVE
  A feed-forward loop involving lactic acid production may potentially occur during the formation of idiopathic pulmonary fibrosis. To provide evidence for this feed-forward loop, we used acidoCEST MRI to measure the extracellular pH (pHe), while also measuring percent uptake of the contrast agent, lesion size, and the apparent diffusion coefficient (ADC).
  
  
  METHODS
  We developed a respiration-gated version of acidoCEST MRI to improve the measurement of pHe and percent uptake in lesions. We also used T2-weighted MRI to measure lesion volumes and diffusion-weighted MRI to measure ADC.
  
  
  RESULTS
  The longitudinal changes in average pHe and % uptake of the contrast agent were inversely related to reduction in lung lesion volume. The average ADC did not change during the time frame of the study.
  
  
  CONCLUSIONS
  The increase in pHe during the reduction in lesion volume indicates a role for lactic acid in the proposed feed-forward loop of IPF.
authors.affiliation: Biomedical Engineering Graduate Interdisciplinary Program, University of Arizona, Tucson, AZ, USA.
authors.forename: Kyle M
authors.initials: KM
authors.lastname: Jones
authors.forename: Edward A
authors.initials: EA
authors.lastname: Randtke
authors.forename: Christine M
authors.initials: CM
authors.lastname: Howison
authors.forename: Julio
authors.initials: J
authors.lastname: Cárdenas-Rodríguez
authors.forename: Patricia J
authors.initials: PJ
authors.lastname: Sime
authors.forename: Matthew R
authors.initials: MR
authors.lastname: Kottmann
authors.forename: Mark D
authors.initials: MD
authors.lastname: Pagel
mesh_terms: D000818:Animals; D003094:Collagen / Q000378:metabolism; D003198:Computer Simulation; D004195:Disease Models, Animal; D005110:Extracellular Space / Q000737:chemistry*; D006863:Hydrogen-Ion Concentration; D054990:Idiopathic Pulmonary Fibrosis / Q000378:metabolism*; D007479:Iopamidol / Q000737:chemistry / Q000494:pharmacology; D008168:Lung / Q000473:pathology; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D008810:Mice, Inbred C57BL; D012119:Respiration
chemical_list: D003094:Collagen; D007479:Iopamidol