Tractograms have large number of false positives. One possible solution is to use anatomically relevant atlases of bundles to create priors of known bundles and therefore concentrate on the true positives. However this requires registration with incomplete atlases that contain only a few known bundles. A new asymmetric cost function extensively advances the direct registration of tractograms to atlases with a small number of bundles. Furthermore, although existing ROI filtered atlases can miss important parts of bundles, by using a pruning method using streamline centroids, these parts can be found, and the false positives can be extensively reduced.