Methodology for the Estimation of the Extension of a White Matter Tract Into and Through Associated Grey Matter

Daniel J. Tozer¹, Declan Chard¹, Olga Ciccarelli², Benedetta Bodini², David H. Miller¹, Alan J. Thompson², Claudia Angela Michela Wheeler-Kingshott¹

The definition of areas of grey matter (GM) that are associated with specific white matter tracts is important for studies investigating the spatio-temporal relationship between the two. The work proposes a method for extending a white matter tract calculated from diffusion MRI through the GM using a geometrical extension of those pixels on the tract edge, which are in or abut GM, to the nearest point on the outer GM boundary. It was found that running the extension in 3 orthogonal 2D planes included more tissue than running the process in 3D, which may be preferable in many cases.