High-field (3.0 T) functional MRI sequential epoch analysis: An example for motion control analysis

The widely accepted method of blood oxygenation level dependent functional magnetic resonance imaging (BOLD-fMRI) is a subtractive approach of state related analysis based on pictorial statistics, analogous to its predecessor, H₂O¹⁵ positron emission tomography (H₂O¹⁵-PET). Although BOLD-fMRI has been shown to have several definite advantages over H₂O¹⁵- PET, it has also been found to be much more artifact prone. This is primarily due to pixel misalignment of raw image data. Furthermore, similar to H₂O¹⁵-PET, conventional means for pictorial analysis in BOLD-fMRI tends to be limited by the relatively low specificity of the observed activation. To overcome this limitation, we investigated a technique for BOLD-fMRI, sequential epoch analysis (SEA), on a high-field (3.0 T) system. The method allows for experimental designs comparable to neurophysiological techniques in primates and enables determination of activation of a selected cerebral cortical region of interest corresponding to a specific task. Utilizing SEA, we successfully identified a specific area within the premotor cortex which is activated complementary to the contralateral hand motion. The findings have strong implications regarding the neurological substrate responsible for the well described clinical phenomenon of physiological mirror movements in infants. The current study validated SEA BOLD-fMRI on a high-field system as a complementary method in the pictorial analysis of conventional fMRI, effectively offsetting the inherent problems of the conventional method, principally pixel misalignment and the relatively low specificity of the observed activation.