title: MARGA: multispectral adaptive region growing algorithm for brain extraction on axial MRI.
abstract: Brain extraction, also known as skull stripping, is one of the most important preprocessing steps for many automatic brain image analysis. In this paper we present a new approach called Multispectral Adaptive Region Growing Algorithm (MARGA) to perform the skull stripping process. MARGA is based on a region growing (RG) algorithm which uses the complementary information provided by conventional magnetic resonance images (MRI) such as T1-weighted and T2-weighted to perform the brain segmentation. MARGA can be seen as an extension of the skull stripping method proposed by Park and Lee (2009) [1], enabling their use in both axial views and low quality images. Following the same idea, we first obtain seed regions that are then spread using a 2D RG algorithm which behaves differently in specific zones of the brain. This adaptation allows to deal with the fact that middle MRI slices have better image contrast between the brain and non-brain regions than superior and inferior brain slices where the contrast is smaller. MARGA is validated using three different databases: 10 simulated brains from the BrainWeb database; 2 data sets from the National Alliance for Medical Image Computing (NAMIC) database, the first one consisting in 10 normal brains and 10 brains of schizophrenic patients acquired with a 3T GE scanner, and the second one consisting in 5 brains from lupus patients acquired with a 3T Siemens scanner; and 10 brains of multiple sclerosis patients acquired with a 1.5T scanner. We have qualitatively and quantitatively compared MARGA with the well-known Brain Extraction Tool (BET), Brain Surface Extractor (BSE) and Statistical Parametric Mapping (SPM) approaches. The obtained results demonstrate the validity of MARGA, outperforming the results of those standard techniques.
authors.affiliation: Department of Computer Architecture and Technology, University of Girona, Girona, Spain. Electronic address: eloyroura@eia.udg.edu.
authors.forename: Eloy
authors.initials: E
authors.lastname: Roura
authors.affiliation: Department of Computer Architecture and Technology, University of Girona, Girona, Spain. Electronic address: aoliver@eia.udg.edu.
authors.forename: Arnau
authors.initials: A
authors.lastname: Oliver
authors.affiliation: Department of Computer Architecture and Technology, University of Girona, Girona, Spain. Electronic address: mcabezas@eia.udg.edu.
authors.forename: Mariano
authors.initials: M
authors.lastname: Cabezas
authors.affiliation: Girona Magnetic Resonance Center, Girona, Spain.
authors.forename: Joan C
authors.initials: JC
authors.lastname: Vilanova
authors.affiliation: Magnetic Resonance Unit, Department of Radiology, Vall d'Hebron University Hospital, Barcelona, Spain.
authors.forename: Alex
authors.initials: A
authors.lastname: Rovira
authors.affiliation: Multiple Sclerosis and Neuroimmunology Unit, Dr. Josep Trueta University Hospital, Institut d'Investigació Biomèdica de Girona, Girona, Spain.
authors.forename: Lluís
authors.initials: L
authors.lastname: Ramió-Torrentà
authors.affiliation: Department of Computer Architecture and Technology, University of Girona, Girona, Spain. Electronic address: llado@eia.udg.edu.
authors.forename: Xavier
authors.initials: X
authors.lastname: Lladó
mesh_terms: D000465:Algorithms; D001931:Brain Mapping; D016022:Case-Control Studies; D016208:Databases, Factual; D006801:Humans; D008279:Magnetic Resonance Imaging / Q000379:methods*; D012559:Schizophrenia / Q000473:pathology*
keywords: Biomedical engineering; Image analysis; Image segmentation; Magnetic resonance imaging; Skull stripping