Should I use top-down or bottom-up phase encoding view order for fMRI?
The Center recommends bottom-up view order for fMRI. Using top-down view order may generate more gradient heating. However, one may choose to use top-down view order for the following considerations: • The geometric distortion has less impact to the region of the interest in top-down than in bottom up view order. • more slices or better spatial coverage is needed while no other means can achieve that. Please continue reading for details about the above mentioned considerations. Phase encoding view order refers to the direction in which the Kspace is acquired. In top-down view order, acquisition starts from the top the Kspace; whereas in bottom up view order, acquisition starts from the bottom of the Kspace. Please note that phase encoding view order is not the same as phase encoding direction. Phase encoding direction refers to the physical dimension in which the phase encoding gradients are applied, e.g. left-right, anterior to posterior, or superior to inferior. Each phase encoding d
