Functional imaging by I0- and T2*-parameter mapping using multi-image EPI.
A new functional imaging method has been developed and used to measure T2*- and initial intensity (I0)-parameter maps of multiple slices during activation of the cortex with high temporal resolution. Multiple echo-planar images (EPIs) are read out after a single excitation of the spin system, leading to several images with increasing effective echo times. Changes induced by primary visual stimulation in T2* and I0 were measured in eight subjects. Although stimulation-induced increases in I0 only occurred at short repetition times, T2* increased from 57.3 to 60.9 ms on average. The method combines the high stability of a single shot EPI experiment with the high information content of a multiecho acquisition. In addition, stimulation-induced changes in inflow can be easily separated from true blood oxygenation level dependent (BOLD) signal changes.
Speck
O
O
Department of Radiology, University of Freiburg, Germany.
Hennig
J
J
D001143:Arousal / Q000502:physiology*; D001931:Brain Mapping; D002540:Cerebral Cortex / Q000502:physiology*; D017352:Echo-Planar Imaging / Q000295:instrumentation*; D004867:Equipment Design; D006801:Humans; D007091:Image Processing, Computer-Assisted; D008279:Magnetic Resonance Imaging / Q000295:instrumentation*; D010101:Oxygen Consumption / Q000502:physiology; D010364:Pattern Recognition, Visual / Q000502:physiology; D012680:Sensitivity and Specificity; D014793:Visual Cortex / Q000502:physiology