Diffusion encoding with 2D gradient trajectories yields natural contrast for 3D fiber orientation
Wedeen V, Dai G, Wang R, Benner T, Tseng W
Athinoula A. Martinos Center
A novel diffusion contrast mechanism is presented. Gradient pulse trains following appropriate trajectories within a prescribed 2D plane in q-space create diffusion contrast specific for fibers oriented perpendicular to the specified plane. Theory and experimental data, tractography in fixed marmoset brain and in human subjects, are presented, showing that high-resolution diffusion MRI with such gradients yield accurate fiber orientation density functions directly from the signal, without need of reconstruction by integral transform. Opportunities are discussed for quantitation of fiber geometry including fiber diameter.