humanbraintumours创新.PDFVIP

Ortega-Martorell et al. BMC Bioinformatics 2012, 13:38 /1471-2105/13/38 RESEARCH ARTICLE Open Access Non-negative matrix factorisation methods for the spectral decomposition of MRS data from human brain tumours 1,2,3 4* 5 2,1,3 1,2,3* Sandra Ortega-Martorell , Paulo JG Lisboa , Alfredo Vellido , Margarida Julià-Sapé and Carles Arús Abstract Background: In-vivo single voxel proton magnetic resonance spectroscopy (SV 1H-MRS), coupled with supervised pattern recognition (PR) methods, has been widely used in clinical studies of discrimination of brain tumour types and follow-up of patients bearing abnormal brain masses. SV 1H-MRS provides useful biochemical information about the metabolic state of tumours and can be performed at short ( 45 ms) or long ( 45 ms) echo time (TE), each with particular advantages. Short-TE spectra are more adequate for detecting lipids, while the long-TE provides a much flatter signal baseline in between peaks but also negative signals for metabolites such as lactate. Both, lipids and lactate, are respectively indicative of specific metabolic processes taking place. Ideally, the information provided by both TE should be of use for clinical purposes. In this study, we characterise the performance of a range of Non-negative Matrix Factorisation (NMF) methods in two respects: first, to derive sources correlated with the mean spectra of known tissue types (tumours and normal tissue); second, taking the best performing NMF method for source separation, we compare its accuracy for class assignment when using the mixing matrix directly as a basis for classification, as against using the method for dimensionality reduction (DR). For this, we used SV 1H