A simple metric for the shared diffusion anisotropy between two voxels is proposed. The metric has large values when the diffusion is highly anisotropic in both voxels and oriented in the same direction. This metric can be used in several ways, three of which are illustrated in this article. First, the metric can be used to rapidly calculate a fractional anisotropy measure using an arbitrary number of measured diffusion values. Second, a simple way to exploit the metric for filtering DWI data with neighboring voxels with similar diffusion characteristics is shown. Third, the metric can be used to create color images that reflect tract orientation.
Copyright 2003 Wiley-Liss, Inc.