This function guesses the assignment of image volumes to shells, expanding a list of unique b-values to one value per volume. This is achieved by performing k-means clustering on the mean intensities of each volume. The set of unique b-values must be known beforehand, and no sanity checking is performed on the intensities for each shell except ordering.
fillShells(image, bValues)A numeric vector expanding the original bValues to one value
per volume of the image.
A 4D diffusion-weighted image, whose mean volume intensities will be used to cluster the acquisition into shells. It does not need to already have gradient direction or b-value information associated with it.
A numeric vector of unique b-values.
Jon Clayden
Please cite the following reference when using TractoR in your work:
J.D. Clayden, S. Muñoz Maniega, A.J. Storkey, M.D. King, M.E. Bastin & C.A. Clark (2011). TractoR: Magnetic resonance imaging and tractography with R. Journal of Statistical Software 44(8):1-18. tools:::Rd_expr_doi("10.18637/jss.v044.i08").