Resolution and segmentation of hyperspectral biomedical images by Multivariate Curve Resolution-Alternating Least Squares

MCR-ALS is a resolution method that has been applied in many different fields, such as process analysis, environmental data and, recently, hyperspectral image analysis. In this context, the algorithm provides the distribution maps and the pure spectra of the image constituents from the sole information in the raw image measurement. Based on the distribution maps and spectra obtained, additional information can be easily derived, such as identification of constituents when libraries are available or quantitation within the image, expressed as constituent signal contribution. This work summarizes first the protocol followed for the resolution on two examples of kidney calculi, taken as representations of images with major and minor compounds, respectively.Image segmentation allows separating regions of images according to their pixel similarity and is also relevant in the biomedical field to differentiate healthy from non-healthy regions in tissues or to identify sample regions with distinct properties. Information on pixel similarity is enclosed not only in pixel spectra, but also in other smaller pixel representations, such as PCA scores. In this paper, we propose the use of MCR scores (concentration profiles) for segmentation purposes. K-means results obtained from different pixel representations of the data set are compared. The main advantages of the use of MCR scores are the interpretability of the class centroids and the compound-wise selection and preprocessing of the input information in the segmentation scheme.

Graphical abstractThe article summarizes the usefulness of Multivariate Curve Resolution to provide distribution maps (C matrix) and pure spectra (ST matrix) of compounds from raw biomedical hyperspectral images. An additional interesting aspect is the possibility to obtain interpretable segmentation schemes by using the obtained MCR scores (C matrix) as starting point.Figure optionsDownload full-size imageDownload as PowerPoint slideHighlights► MCR-ALS provides distribution maps and pure spectra of compounds in biomedical images ► MCR scores (C matrix) can be used as starting point for image segmentation purposes. ► Use of MCR scores offers fast computation and gives interpretable segmentation schemes. ► Use of MCR scores allows selecting compound contributions for segmentation ► Use of MCR scores allows profile pretreatment for segmentation (e.g. autoscaling).