title: Optimization of blood oxygenation level-dependent sensitivity in magnetic resonance imaging using intermolecular double-quantum coherence.
abstract: OBJECTIVE
  To optimize timing parameters in an intermolecular double-quantum coherence (iDQC) imaging pulse sequence for overall image signal-to-noise ratio (SNR) and blood oxygenation level-dependent (BOLD) sensitivity for brain functional imaging.
  
  
  METHODS
  Fresh human blood was measured under different oxygenation conditions, and human brain functional magnetic resonance (fMR) images in three normal volunteers were obtained, using iDQC techniques at 1.5 T. The dependence of SNR and BOLD sensitivity was measured as a function of time delays after the iDQC evolution period.
  
  
  RESULTS
  A time delay after the iDQC evolution period tau can be adjusted either to refocus the dephasing accumulated during tau, thus increasing SNR, with full rephasing occurring at delay = +/-2tau (for iDQC order n = +/-2), or to enhance BOLD effects with consequent reduced image SNR at delay = 0.
  
  
  CONCLUSIONS
  Image SNR and BOLD sensitivity often impose different requirements for iDQC image sequence design and timing parameter selections. It is therefore important to select properly relevant parameters for different applications.
authors.affiliation: Department of Radiology, University of Rochester, Rochester, New York, USA. jianhui.zhong@rochester.edu
authors.forename: Jianhui
authors.initials: J
authors.lastname: Zhong
authors.forename: Zhong
authors.initials: Z
authors.lastname: Chen
authors.forename: W Edmund
authors.initials: WE
authors.lastname: Kwok
authors.forename: Scott
authors.initials: S
authors.lastname: Kennedy
authors.forename: Zhiyang
authors.initials: Z
authors.lastname: You
mesh_terms: D000161:Acoustic Stimulation; D001769:Blood / Q000378:metabolism*; D001921:Brain / Q000033:anatomy & histology*; D001931:Brain Mapping; D006801:Humans; D008279:Magnetic Resonance Imaging / Q000379:methods*; D010100:Oxygen / Q000378:metabolism*; D012680:Sensitivity and Specificity
chemical_list: D010100:Oxygen