A new fMRI postprocessing HASTE map technique to increase accuracyof the cortical BOLD activation in the visual cortex

摘要

In functional MRI (fMRT), blood oxygenation level dependent (BOLD)imaging studies of the brain activated voxels often appear in sulci.True positive activation appears due to the presence of paramagneticdeoxyhemoglobin blood because of cortical neural activity. Falsepositive activation may occur within noncortical cerebrospinal fluid(CSF) spaces due to activation in vessels and CFS how within sulciadjacent to the area performing a task. Also, true positivetask-nonrelevant BOLD activation appearing in sulci away from theneuroanatomical regions associated with a specific task was assumed asfalse activation. Such false activations may lead to misinterpretationsof fMRI maps. The currently used echo-planar imaging (EPI) techniqueslack high spatial resolution to differentiate such false positiveactivation from true positive activation. The specific aim of the workwas to develop an fMRI image postprocessing technique to identify thesulci in the EPI images using half-Fourier turbo-spin echo (HASTE)sequence. High resolution HASTE images are insensitive to susceptibilityeffect and have high contrast differences between areas filled withfluids and brain parenchyma. Therefore these HASTE images can beeffectively used to clearly separate CSF in the sulci from othercortical brain structures where the true BOLD activation ispresent