Semi-supervised Learning of Sparse Linear Models in Mass Spectral Imaging

摘要

We present an approach to learn predictive models and perform variable selection by incorporating structural information from Mass Spectral Imaging (MSI) data. We explore the use of a smooth quadratic penalty to model the natural ordering of the physical variables, that is the mass-to-charge (m/z) ratios. Thereby, estimated model parameters for nearby variables are enforced to smoothly vary. Similarly, to overcome the lack of labeled data we model the spatial proximity among spectra by means of a connectivity graph over the set of predicted labels. We explore the usefulness of this approach in a mouse brain MSI data set.