TY - JOUR
T1 - Quantitative assessment of blood inflow effects in functional MRI signals
AU - Gao, Jia Hong
AU - Miller, Ira
AU - Lai, Song
AU - Xiong, Jinhu
AU - Fox, Peter T.
PY - 1996/8
Y1 - 1996/8
N2 - Functional MRI (fMRI) signal dependence on changes in blood flow velocities were analyzed for both conventional and echoplanar (EPI) gradient-echo pulse sequences. As the flow velocity increases, the fMRI signal increases monotonically in spoiled gradient-echo sequences, while the fMRI signal may increase or decrease in conventional refocused gradient- echo sequences. A larger flip angle generates a larger inflow contribution to the fMRI signal. For conventional gradient-echo sequences, the inflow contribution to the fMRI images is dominated by the cortical draining veins, while its effect on capillaries is generally small and may be negligible in the spoiled sequences. For EPI gradient-echo sequences, the contribution from inflow effects is relatively small, as compared with the blood oxygen level-dependent (BOLD) contribution, to the fMRI signal, not only for capillaries but also for the cortical draining veins.
AB - Functional MRI (fMRI) signal dependence on changes in blood flow velocities were analyzed for both conventional and echoplanar (EPI) gradient-echo pulse sequences. As the flow velocity increases, the fMRI signal increases monotonically in spoiled gradient-echo sequences, while the fMRI signal may increase or decrease in conventional refocused gradient- echo sequences. A larger flip angle generates a larger inflow contribution to the fMRI signal. For conventional gradient-echo sequences, the inflow contribution to the fMRI images is dominated by the cortical draining veins, while its effect on capillaries is generally small and may be negligible in the spoiled sequences. For EPI gradient-echo sequences, the contribution from inflow effects is relatively small, as compared with the blood oxygen level-dependent (BOLD) contribution, to the fMRI signal, not only for capillaries but also for the cortical draining veins.
KW - EPI
KW - flow
KW - functional MRI (fMRI)
KW - gradient-echo sequence
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U2 - 10.1002/mrm.1910360219
DO - 10.1002/mrm.1910360219
M3 - Article
C2 - 8843386
AN - SCOPUS:0029783656
SN - 0740-3194
VL - 36
SP - 314
EP - 319
JO - Magnetic Resonance in Medicine
JF - Magnetic Resonance in Medicine
IS - 2
ER -