title: Tumor feature visualization with unsupervised learning.
abstract: Dynamic contrast enhanced magnetic resonance imaging (DCE MRI) is applied for diagnosis and therapy control of breast cancer. The malignancy of a lesion is expressed in the average signal kinetics of selected regions of interest (ROI) representing the lesion. The technique is reported to characterize malignant tumors with high sensitivity and highly variable specificity. Computer-based diagnosis (CAD) systems have been proposed to analyze and classify signal time curve data, extracted from hand selected ROI in the DCE MRI data. In this paper, we apply the self-organizing map (SOM) to a set of time curve feature vectors of single voxels from seven benign lesions and seven malignant tumors. Applying the SOM we are able to project the time curve values of each voxel on a two-dimensional map. The results show, that the SOM is able to visualize the hidden two-dimensional structure of the six-dimensional signal space. Using the trained SOM, we are able to identify voxels with benign or malignant signal characteristics and to visualize lesion cross-sections with pseudo-colors. A comparison with the established three time points method shows that the SOM has clear potential for deriving visualization parameters in DCE MRI analysis.
authors.affiliation: Applied Neuroinformatics Group, Faculty of Technology, Bielefeld University, P.O. Box 100131, D-33501 Bielefeld, Germany. tnattkem@techfak.uni-bielefeld.de
authors.forename: Tim W
authors.initials: TW
authors.lastname: Nattkemper
authors.forename: Axel
authors.initials: A
authors.lastname: Wismüller
mesh_terms: D001943:Breast Neoplasms / Q000473:pathology*; D003287:Contrast Media; D003936:Diagnosis, Computer-Assisted; D005260:Female; D019786:Gadolinium DTPA; D006801:Humans; D007091:Image Processing, Computer-Assisted / Q000379:methods*; D008279:Magnetic Resonance Imaging; D016571:Neural Networks, Computer
chemical_list: D003287:Contrast Media; D019786:Gadolinium DTPA