“…Methods include morphological (Lohmann et al, 2003), line integral (Aganj et al, 2009;Scott et al, 2009), Laplacian (Jones et al, 2000) and registration (Das et al, 2009) based approaches. Laplacian approaches (Hutton et al, 2008;Acosta et al, 2009;Cardoso et al, 2011), solve the Laplace equation (Jones et al, 2000) using boundary value relaxation (Press et al, 1991) or matrix methods (Haidar et al, 2005), calculate thickness by integrating the tangent to the Laplacian scalar field (Jones et al, 2000), summing the Euclidean distance from neighbouring voxels on the same streamline, or using a partial differential equation (Yezzi and Prince, 2003) with boundaries set to zero (Yezzi and Prince, 2003), half the mean voxel dimension (Diep et al, 2007) or using Lagrangian initialisation (Bourgeat et al, 2008;Acosta et al, 2009).…”