title: Spin-echo and gradient-echo EPI of human brain activation using BOLD contrast: a comparative study at 1.5 T.
abstract: In this study, Blood Oxygenation Level Dependent (BOLD) contrast in the detection of human brain activation was compared between spin-echo and gradient-echo echo-planar sequences at 1.5 T. Time course series of spin-echo and gradient-echo images containing the primary motor cortex were collected during rest (no finger movement) and activation (finger movement). Each time course series was collected using a different TE. Resting and active state signal intensities at each TE were measured in identical regions in the motor cortex. From these data, resting and active state R2 (1/T2) and R2* (1/T2*) values were obtained. Across four subjects, brain activation produced an average R2 change of -0.16 +/- 0.02/s (+/- SE), and an average R2* change of -0.55 +/- 0.08/s. The average delta R2*/delta R2 ratio was 3.52 +/- 0.56. The average gradient-echo/spin-echo ratio of activation-induced signal changes at the TE for maximal BOLD contrast for each sequence (TE approximately T2* and T2) was calculated to be 1.87 +/- 0.40.
authors.affiliation: Biophysics Research Institute, Medical College of Wisconsin, Milwaukee 53226.
authors.forename: P A
authors.initials: PA
authors.lastname: Bandettini
authors.forename: E C
authors.initials: EC
authors.lastname: Wong
authors.forename: A
authors.initials: A
authors.lastname: Jesmanowicz
authors.forename: R S
authors.initials: RS
authors.lastname: Hinks
authors.forename: J S
authors.initials: JS
authors.lastname: Hyde
mesh_terms: D000328:Adult; D001921:Brain / Q000033:anatomy & histology* / Q000098:blood supply / Q000502:physiology*; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D008954:Models, Biological; D009044:Motor Cortex / Q000033:anatomy & histology / Q000098:blood supply / Q000502:physiology; D010100:Oxygen / Q000097:blood*; D013997:Time Factors
chemical_list: D010100:Oxygen