A Study of Combination fMRI and DTI in A Cognitive Task

Magnetic resonance diffusion tensor imaging (MR-DTI) as a noninvasive technique can investigate the cerebral white matter architecture based on the directional information of diffusion that is related to fiber tract. With the development of DTI technique in recent years, more and more studies of combining fMRI with DTI are used to explore the relationships between functional connectivity and its structural properties in vivo, especially in pathological researches. In our work, we focus on whether functional connectivity takes structural connectivity as its basis in a specific cognitive task in normal brains. Temporal correlation method was used to acquire the functional connectivity network based on fMRI in a picture-naming task. Fractional anisotropy (FA) that denoted the degree of the diffusion anisotropy was calculated using diffusion tensor matrix based on DTI. Then the principle vector of tensor matrix was mapped into X, Y, and Z axes with RGB color and weighting the color brightness by FA. We normalized the two data results before combining them so as to match them better. Then functional connectivity maps were overlaid upon DTI directional color maps that indicated the white matter tract orientation based on the principle vector of tensor matrix. The results showed that the functional connected regions of brain in this cognitive task had white matter connectivity. It may be suggested functional connectivity did take structure as its basis, and the combination of fMRI and DTI could explore effectively the correlation of structure and function in both healthy and disease cerebra.