  We present a geometric framework for aligning white matter fiber tracts. By
registering fiber tracts between brains, one expects to see overlap of
anatomical structures that often provide meaningful comparisons across
subjects. However, the geometry of white matter tracts is highly heterogeneous,
and finding direct tract-correspondence across multiple individuals remains a
challenging problem. We present a novel deformation metric between tracts that
allows one to compare tracts while simultaneously obtaining a registration. To
accomplish this, fiber tracts are represented by an intrinsic mean along with
the deformation fields represented by tangent vectors from the mean. In this
setting, one can determine a parallel transport between tracts and then
register corresponding tangent vectors. We present the results of bundle
alignment on a population of 43 healthy adult subjects.
