Analysis of brain activation patterns using a 3-D scale-space primal sketch

A fundamental problem in brain imaging concerns how to define functional ar eas consisting of neurons that are activated together as populations. We pr opose that this issue can be ideally addressed by a computer vision tool re ferred to as the scale-space primal sketch. This concept has the attractive properties that it allows for automatic and simultaneous extraction of the spatial extent and the significance of regions with locally high activity. In addition, a hierarchical nested tree structure of activated regions and subregions is obtained. The subject in this article is to show how the sca le-space primal sketch can be used for automatic determination of the spati al extent and the significance of rCBF changes. Experiments show the result of applying this approach to functional PET data, including a preliminary comparison with two more traditional clustering techniques. Compared to pre vious approaches, the method overcomes the limitations of performing the an alysis at a single scale or assuming specific models of the data. (C) 1999 Wiley-Liss, Inc.