title: Functional t1ρ imaging in panic disorder.
abstract: BACKGROUND
  Abnormal brain pH has been suggested to play a critical role in panic disorder. To investigate this possibility, we employed a pH-sensitive magnetic resonance (MR) imaging strategy (T1 relaxation in the rotating frame [T1ρ]) and conventional blood oxygen level-dependent (BOLD) imaging.
  
  
  METHODS
  Thirteen panic disorder participants and 13 matched control subjects were enrolled in the study. T1ρ and BOLD were used to study the functional response to a visual flashing checkerboard and their relationship to panic symptoms assessed using the Beck Anxiety Inventory.
  
  
  RESULTS
  In response to visual stimulation, T1ρ imaging revealed a significantly greater increase in the visual cortex of panic disorder participants. T1ρ also detected a stimulus-evoked decrease in the anterior cingulate cortex. Blood oxygen level-dependent imaging detected no functional differences between groups. The correspondence between panic symptoms and functional T1ρ response identified significant relationships within the left inferior parietal lobe, left middle temporal gyrus, and right insula. No relationships were found between panic symptoms and the BOLD signal.
  
  
  CONCLUSIONS
  The data suggest greater activity-evoked T1ρ changes in the visual cortex and anterior cingulate cortex of panic disorder participants. These observations are consistent with a pH dysregulation in panic disorder. In addition, our data suggest that T1ρ imaging may provide information about panic disorder that is distinct from conventional BOLD imaging and may reflect abnormalities in pH and/or brain metabolism.
authors.affiliation: Department of Radiology, University of Iowa, Iowa City, Iowa; Department of Biomedical Engineering, University of Iowa, Iowa City, Iowa; Department of Psychiatry, University of Iowa, Iowa City, Iowa. Electronic address: vincent-magnotta@uiowa.edu.
authors.forename: Vincent A
authors.initials: VA
authors.lastname: Magnotta
authors.affiliation: Department of Radiology, University of Iowa, Iowa City, Iowa.
authors.forename: Casey P
authors.initials: CP
authors.lastname: Johnson
authors.affiliation: Department of Psychiatry, University of Iowa, Iowa City, Iowa.
authors.forename: Robin
authors.initials: R
authors.lastname: Follmer
authors.affiliation: Department of Psychiatry, University of Iowa, Iowa City, Iowa; Department of Neurosurgery, University of Iowa, Iowa City, Iowa.
authors.forename: John A
authors.initials: JA
authors.lastname: Wemmie
mesh_terms: D000328:Adult; D001931:Brain Mapping / Q000379:methods*; D005260:Female; D006179:Gyrus Cinguli / Q000378:metabolism*; D006801:Humans; D006863:Hydrogen-Ion Concentration; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D008875:Middle Aged; D016584:Panic Disorder / Q000378:metabolism*; D056152:Respiratory Rate; D014793:Visual Cortex / Q000378:metabolism*; D055815:Young Adult
keywords: BOLD; T1ρ; brain activation; brain pH; metabolism; panic disorder