Artificial Intelligence in Medicine 20 (2000) 77 – 93 A cooperative framework for segmentation of MRI brain scans Laurence Germond a , Michel Dojat b, *, C. Taylor c , C. Garbay a a Laboratoire TIMC-IMAG, Institut Bonniot, Faculte ´ de Me ´decine, Domaine de la Merci, 38706 La Tronche Cedex, France b Institut National de la Sante ´ et de la Recherche Me ´dicale, U438 -RMN Bioclinique, Centre Hospitalier Uniersitaire -Paillon B, BP 217, 38043 Grenoble Cedex 9, France c Department of Medical Biophysics, Uniersity of Manchester, Stopford Building, Oxford Road, Manchester M139PT, UK Received 10 November 1999; received in revised form 1 February 2000; accepted 27 March 2000 Abstract Automatic segmentation of MRI brain scans is a complex task for two main reasons: the large variability of the human brain anatomy, which limits the use of general knowledge and, inherent to MRI acquisition, the artifacts present in the images that are difficult to process. To tackle these difficulties, we propose to mix, in a cooperative framework, several types of information and knowledge provided and used by complementary individual systems: presently, a multi-agent system, a deformable model and an edge detector. The outcome is a cooperative segmentation performed by a set of region and edge agents constrained automatically and dynamically by both, the specific gray levels in the considered image, statistical models of the brain structures and general knowledge about MRI brain scans. Interactions between the individual systems follow three modes of cooperation: integrative, augmentative and confrontational cooperation, combined during the three steps of the segmentation process namely, the specialization of the seeded-region-growing agents, the fusion of heterogeneous information and the retroaction over slices. The described coopera- tive framework allows the dynamic adaptation of the segmentation process to the own characteristics of each MRI brain scan. Its evaluation using realistic brain phantoms is reported. © 2000 Elsevier Science B.V. All rights reserved. Keywords: Multi-agent system; Cerebral cortex; Active shape model www.elsevier.com/locate/artmed * Corresponding author. Tel.: +33-4-76765748; fax: +33-4-76765896. E-mail address: mdojat@ujf-grenoble.fr (M. Dojat). 0933-3657/00/$ - see front matter © 2000 Elsevier Science B.V. All rights reserved. PII:S0933-3657(00)00054-3