Enhancing the Detection of BOLD Signal in fMRI by Reducing the Partial Volume Effect

Figure 8

The 𝑡-scores are evaluated in the original and 𝑘-space interpolated activation maps in the FEF region in six subjects. The inset drawing shows the spatial relationship of the A- and B-type voxels in the interpolated image to the location of the original voxels, labeled as Os. Each circle in this plot shows an interpolated voxel that has a higher 𝑡-score (𝑦-axis) than the highest 𝑡-score of its nearest original neighbors (𝑥-axis), either an A-type (open circle) or B-type (gray solid circle) voxel. In the 6 interpolated maps, the 𝑡-scores in 62 of a total 304 voxels are higher than the highest 𝑡-scores in the nearest neighboring original voxels, with an average of 13.3% increase of the 𝑡-score. In each of the 6 interpolated voxels shown as dark solid circles, the highest 𝑡-score of its nearest original neighbors is below the threshold of 3.18 in the original maps. These 6 interpolated voxels, indicated by the blue arrows in Figure 7(a), have 𝑡-scores above the threshold and are located at the edge of the multivoxel activated regions. The diagonal line represents the situation when the 𝑡-scores in the original maps are identical to that in the interpolated maps.