Investigation of alternating and continuous functional MRI experimental designs at 1.5 T

Studies the effect of two different functional MRI (fMRI) experimental design parameters on blood oxygenation level dependent (BOLD) signal contrast. The design parameters examined were: (1) the pattern of administering the control and activation conditions; and (2) the quantity of the control signals collected. Six normal volunteers underwent single finger opposition fMRI using T2*-weighted echo planar imaging technique. The BOLD signal contrast was evaluated using analysis of variance on normalized t-values and mean region-of-interest (ROI) intensity. The results demonstrate: (1) the alternating pattern of administering rest and activation epochs produced a more robust statistical difference in BOLD signal than a continuous pattern, and (2) a reduction in the amount of rest signal collected did not result in a statistically significant reduction in the BOLD signal. The results indicate that manipulating such factors of signal collection does alter BOLD signal properties.