Preliminary Observations on Sensitivity and Specificity of Magnetization Transfer Asymmetry for Imaging Myelin of Rat Brain at High Field

Figure 1

Alternate ascending/descending directional navigation (ALADDIN) data acquisition and reconstruction schemes used in this study. Four different types of data acquisition were sequentially performed by alternating the slice acquisition order (ascending and descending, “Asc” and “Des”) and the slice-selection gradient polarity (positive and negative, “Pos” and “Neg”). The on-resonance RF pulses for imaging the prior slices simultaneously act as off-resonance saturation pulses for the present imaging slice. indicates the saturation offset frequency induced by the first prior slice. The four types of images (PosAsc, NegAsc, PosDes, and NegDes) are combined to generate an interslice MT asymmetry (MTA) image. represents the average of the four types of images.