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

Abstract

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 paramagnetic deoxyhemoglobin blood because of cortical neural activity. False positive activation may occur within noncortical cerebrospinal fluid (CSF) spaces due to activation in vessels and CFS how within sulci adjacent to the area performing a task. Also, true positive task-nonrelevant BOLD activation appearing in sulci away from the neuroanatomical regions associated with a specific task was assumed as false activation. Such false activations may lead to misinterpretations of fMRI maps. The currently used echo-planar imaging (EPI) techniques lack high spatial resolution to differentiate such false positive activation from true positive activation. The specific aim of the work was to develop an fMRI image postprocessing technique to identify the sulci in the EPI images using half-Fourier turbo-spin echo (HASTE) sequence. High resolution HASTE images are insensitive to susceptibility effect and have high contrast differences between areas filled with fluids and brain parenchyma. Therefore these HASTE images can be effectively used to clearly separate CSF in the sulci from other cortical brain structures where the true BOLD activation is present.