title: Noncontrast mapping of arterial delay and functional connectivity using resting-state functional MRI: a study in Moyamoya patients.
abstract: OBJECTIVE
  To investigate if delays in resting-state spontaneous fluctuations of the BOLD (sfBOLD) signal can be used to create maps similar to time-to-maximum of the residue function (Tmax) in Moyamoya patients and to determine whether sfBOLD delays affect the results of brain connectivity mapping.
  
  
  METHODS
  Ten patients were scanned at 3 Tesla using a gradient-echo echo planar imaging sequence for sfBOLD imaging. Cross correlation analysis was performed between each brain voxel signal and a reference signal comprised of either the superior sagittal sinus (SSS) or whole brain (WB) average time course. sfBOLD delay maps were created based on the time shift necessary to maximize the correlation coefficient, and compared with dynamic susceptibility contrast Tmax maps. Standard and time-shifted resting-state BOLD connectivity analyses of the default mode network were compared.
  
  
  RESULTS
  Good linear correlations were found between sfBOLD delays and Tmax using the SSS as reference (r(2)  = 0.8, slope = 1.4, intercept = -4.6) or WB (r(2)  = 0.7, slope = 0.8, intercept = -3.2). New nodes of connectivity were found in delayed regions when accounting for delays in the analysis.
  
  
  CONCLUSIONS
  Resting-state sfBOLD imaging can create delay maps similar to Tmax maps without the use of contrast agents in Moyamoya patients. Accounting for these delays may affect the results of functional connectivity maps.
authors.affiliation: Department of Radiology, Stanford University, Stanford, California, USA.
authors.forename: Thomas
authors.initials: T
authors.lastname: Christen
authors.forename: Hesamoddin
authors.initials: H
authors.lastname: Jahanian
authors.forename: Wendy W
authors.initials: WW
authors.lastname: Ni
authors.forename: Deqiang
authors.initials: D
authors.lastname: Qiu
authors.forename: Michael E
authors.initials: ME
authors.lastname: Moseley
authors.forename: Greg
authors.initials: G
authors.lastname: Zaharchuk
mesh_terms: D000328:Adult; D000368:Aged; D001931:Brain Mapping / Q000379:methods*; D003287:Contrast Media; D017352:Echo-Planar Imaging; D005260:Female; D006801:Humans; D007090:Image Interpretation, Computer-Assisted; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D008536:Meglumine / Q000031:analogs & derivatives; D008875:Middle Aged; D009072:Moyamoya Disease / Q000473:pathology*; D009942:Organometallic Compounds; D011446:Prospective Studies
chemical_list: D003287:Contrast Media; D009942:Organometallic Compounds; C064572:gadobenic acid; D008536:Meglumine
keywords: BOLD contrast; MRI; Moyamoya disease; functional connectivity; perfusion; resting-state fMRI